diff --git a/pkg/front_end/lib/src/fasta/type_inference/inference_visitor.dart b/pkg/front_end/lib/src/fasta/type_inference/inference_visitor.dart
index a1f27bcbdef..67247fd1483 100644
--- a/pkg/front_end/lib/src/fasta/type_inference/inference_visitor.dart
+++ b/pkg/front_end/lib/src/fasta/type_inference/inference_visitor.dart
@@ -10207,6 +10207,16 @@ class InferenceVisitorImpl extends InferenceVisitorBase
 
       node.lengthCheckTarget = greaterThanOrEqualTarget.member as Procedure;
       node.lengthCheckType = greaterThanOrEqualTarget.getFunctionType(this);
+    } else if (node.patterns.isEmpty) {
+      ObjectAccessTarget lessThanOrEqualsInvokeTarget = findInterfaceMember(
+          lengthType, lessThanOrEqualsName, node.fileOffset,
+          includeExtensionMethods: true,
+          callSiteAccessKind: CallSiteAccessKind.operatorInvocation);
+      assert(lessThanOrEqualsInvokeTarget.isInstanceMember ||
+          lessThanOrEqualsInvokeTarget.isObjectMember);
+
+      node.lengthCheckTarget = lessThanOrEqualsInvokeTarget.member as Procedure;
+      node.lengthCheckType = lessThanOrEqualsInvokeTarget.getFunctionType(this);
     } else {
       ObjectAccessTarget equalsInvokeTarget = findInterfaceMember(
           lengthType, equalsName, node.fileOffset,
@@ -10607,16 +10617,26 @@ class InferenceVisitorImpl extends InferenceVisitorBase
 
       node.lengthCheckTarget = greaterThanOrEqualTarget.member as Procedure;
       node.lengthCheckType = greaterThanOrEqualTarget.getFunctionType(this);
+    } else if (node.entries.isEmpty) {
+      ObjectAccessTarget lessThanOrEqualInvokeTarget = findInterfaceMember(
+          lengthType, lessThanOrEqualsName, node.fileOffset,
+          includeExtensionMethods: true,
+          callSiteAccessKind: CallSiteAccessKind.operatorInvocation);
+      assert(lessThanOrEqualInvokeTarget.isInstanceMember ||
+          lessThanOrEqualInvokeTarget.isObjectMember);
+
+      node.lengthCheckTarget = lessThanOrEqualInvokeTarget.member as Procedure;
+      node.lengthCheckType = lessThanOrEqualInvokeTarget.getFunctionType(this);
     } else {
-      ObjectAccessTarget equalsInvokeTarget = findInterfaceMember(
+      ObjectAccessTarget equalInvokeTarget = findInterfaceMember(
           lengthType, equalsName, node.fileOffset,
           includeExtensionMethods: true,
           callSiteAccessKind: CallSiteAccessKind.operatorInvocation);
-      assert(equalsInvokeTarget.isInstanceMember ||
-          equalsInvokeTarget.isObjectMember);
+      assert(equalInvokeTarget.isInstanceMember ||
+          equalInvokeTarget.isObjectMember);
 
-      node.lengthCheckTarget = equalsInvokeTarget.member as Procedure;
-      node.lengthCheckType = equalsInvokeTarget.getFunctionType(this);
+      node.lengthCheckTarget = equalInvokeTarget.member as Procedure;
+      node.lengthCheckType = equalInvokeTarget.getFunctionType(this);
     }
 
     ObjectAccessTarget containsKeyTarget = findInterfaceMember(
diff --git a/pkg/front_end/lib/src/fasta/type_inference/matching_expressions.dart b/pkg/front_end/lib/src/fasta/type_inference/matching_expressions.dart
index e9895924b9f..80cce0fc3a9 100644
--- a/pkg/front_end/lib/src/fasta/type_inference/matching_expressions.dart
+++ b/pkg/front_end/lib/src/fasta/type_inference/matching_expressions.dart
@@ -128,16 +128,28 @@ class MatchingExpressionVisitor
             fileOffset: node.fileOffset);
       }
     } else {
-      CacheableExpression constExpression = matchingCache
-          .createIntConstant(node.patterns.length, fileOffset: node.fileOffset);
+      int length = node.patterns.length;
+      CacheableExpression constExpression =
+          matchingCache.createIntConstant(length, fileOffset: node.fileOffset);
 
-      lengthCheck = matchingCache.createEqualsExpression(
-          lengthGet,
-          constExpression,
-          new DelayedEqualsExpression(lengthGet, constExpression,
-              node.lengthCheckTarget, node.lengthCheckType!,
-              fileOffset: node.fileOffset),
-          fileOffset: node.fileOffset);
+      if (length == 0) {
+        lengthCheck = matchingCache.createComparisonExpression(
+            lengthGet,
+            lessThanOrEqualsName.text,
+            constExpression,
+            new DelayedInstanceInvocation(lengthGet, node.lengthCheckTarget,
+                node.lengthCheckType!, [constExpression],
+                fileOffset: node.fileOffset),
+            fileOffset: node.fileOffset);
+      } else {
+        lengthCheck = matchingCache.createEqualsExpression(
+            lengthGet,
+            constExpression,
+            new DelayedEqualsExpression(lengthGet, constExpression,
+                node.lengthCheckTarget, node.lengthCheckType!,
+                fileOffset: node.fileOffset),
+            fileOffset: node.fileOffset);
+      }
     }
 
     DelayedExpression? matchingExpression;
@@ -288,16 +300,27 @@ class MatchingExpressionVisitor
             fileOffset: node.fileOffset);
       }
     } else {
-      CacheableExpression constExpression = matchingCache
-          .createIntConstant(node.entries.length, fileOffset: node.fileOffset);
-
-      lengthCheck = matchingCache.createEqualsExpression(
-          lengthGet,
-          constExpression,
-          new DelayedEqualsExpression(lengthGet, constExpression,
-              node.lengthCheckTarget, node.lengthCheckType!,
-              fileOffset: node.fileOffset),
-          fileOffset: node.fileOffset);
+      int length = node.entries.length;
+      CacheableExpression constExpression =
+          matchingCache.createIntConstant(length, fileOffset: node.fileOffset);
+      if (length == 0) {
+        lengthCheck = matchingCache.createComparisonExpression(
+            lengthGet,
+            lessThanOrEqualsName.text,
+            constExpression,
+            new DelayedInstanceInvocation(lengthGet, node.lengthCheckTarget,
+                node.lengthCheckType!, [constExpression],
+                fileOffset: node.fileOffset),
+            fileOffset: node.fileOffset);
+      } else {
+        lengthCheck = matchingCache.createEqualsExpression(
+            lengthGet,
+            constExpression,
+            new DelayedEqualsExpression(lengthGet, constExpression,
+                node.lengthCheckTarget, node.lengthCheckType!,
+                fileOffset: node.fileOffset),
+            fileOffset: node.fileOffset);
+      }
     }
 
     DelayedExpression? matchingExpression;
diff --git a/pkg/front_end/testcases/late_lowering/caching.dart.strong.expect b/pkg/front_end/testcases/late_lowering/caching.dart.strong.expect
index 59f92d99f55..af02164d833 100644
--- a/pkg/front_end/testcases/late_lowering/caching.dart.strong.expect
+++ b/pkg/front_end/testcases/late_lowering/caching.dart.strong.expect
@@ -175,7 +175,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -375,7 +375,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -667,7 +667,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t81 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t81 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -931,7 +931,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t130 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t130 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t95 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/late_lowering/caching.dart.strong.transformed.expect b/pkg/front_end/testcases/late_lowering/caching.dart.strong.transformed.expect
index 077f72a3096..abad3c25c2a 100644
--- a/pkg/front_end/testcases/late_lowering/caching.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/late_lowering/caching.dart.strong.transformed.expect
@@ -175,7 +175,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -375,7 +375,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -667,7 +667,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t84 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t84 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -931,7 +931,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t134 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t134 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t98 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/late_lowering/caching.dart.weak.expect b/pkg/front_end/testcases/late_lowering/caching.dart.weak.expect
index acdad41ed72..385dd50b836 100644
--- a/pkg/front_end/testcases/late_lowering/caching.dart.weak.expect
+++ b/pkg/front_end/testcases/late_lowering/caching.dart.weak.expect
@@ -176,7 +176,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -376,7 +376,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -668,7 +668,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t81 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t81 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -932,7 +932,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t130 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t130 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t95 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/late_lowering/caching.dart.weak.modular.expect b/pkg/front_end/testcases/late_lowering/caching.dart.weak.modular.expect
index acdad41ed72..385dd50b836 100644
--- a/pkg/front_end/testcases/late_lowering/caching.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/late_lowering/caching.dart.weak.modular.expect
@@ -176,7 +176,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -376,7 +376,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -668,7 +668,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t81 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t81 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -932,7 +932,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t130 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t130 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t95 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/late_lowering/caching.dart.weak.transformed.expect b/pkg/front_end/testcases/late_lowering/caching.dart.weak.transformed.expect
index 72a61ee827e..6d52be29dcb 100644
--- a/pkg/front_end/testcases/late_lowering/caching.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/late_lowering/caching.dart.weak.transformed.expect
@@ -176,7 +176,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -376,7 +376,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -668,7 +668,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t81 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t81 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -932,7 +932,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t130 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t130 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t95 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/patterns/caching.dart.strong.expect b/pkg/front_end/testcases/patterns/caching.dart.strong.expect
index 3daac6d72cc..7088f69592b 100644
--- a/pkg/front_end/testcases/patterns/caching.dart.strong.expect
+++ b/pkg/front_end/testcases/patterns/caching.dart.strong.expect
@@ -145,7 +145,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -312,7 +312,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -556,7 +556,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t44 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t44 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -775,7 +775,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t78 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t78 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t58 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/patterns/caching.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/caching.dart.strong.transformed.expect
index d197d9738a7..a793d4e2263 100644
--- a/pkg/front_end/testcases/patterns/caching.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/patterns/caching.dart.strong.transformed.expect
@@ -165,7 +165,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -354,7 +354,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -630,7 +630,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t47 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t47 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -879,7 +879,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t82 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t82 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t61 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/patterns/caching.dart.weak.expect b/pkg/front_end/testcases/patterns/caching.dart.weak.expect
index defdaa4ffc3..352c39f76e2 100644
--- a/pkg/front_end/testcases/patterns/caching.dart.weak.expect
+++ b/pkg/front_end/testcases/patterns/caching.dart.weak.expect
@@ -146,7 +146,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -313,7 +313,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -557,7 +557,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t44 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t44 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -776,7 +776,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t78 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t78 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t58 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/patterns/caching.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/caching.dart.weak.modular.expect
index defdaa4ffc3..352c39f76e2 100644
--- a/pkg/front_end/testcases/patterns/caching.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/patterns/caching.dart.weak.modular.expect
@@ -146,7 +146,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -313,7 +313,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -557,7 +557,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t44 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t44 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -776,7 +776,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t78 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final dynamic #t78 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t58 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/patterns/caching.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/caching.dart.weak.transformed.expect
index 3c94e357b56..75d2d118ede 100644
--- a/pkg/front_end/testcases/patterns/caching.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/patterns/caching.dart.weak.transformed.expect
@@ -166,7 +166,7 @@ static method ifCase(dynamic o) → core::int {
   }
   {
     final synthesized dynamic #20#0 = o;
-    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+    if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
       return 21;
     }
   }
@@ -355,7 +355,7 @@ static method ifCaseElse(dynamic o) → core::int {
                                           }
                                           else {
                                             final synthesized dynamic #20#0 = o;
-                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C12) {
+                                            if(#20#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #20#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C12){(core::num) → core::bool}) {
                                               return 21;
                                             }
                                             else {
@@ -631,7 +631,7 @@ static method switchStatement(dynamic o) → core::int {
       }
     }
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t44 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t44 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
         {
           return 21;
         }
@@ -880,7 +880,7 @@ static method switchExpression(dynamic o) → core::int {
         }
       }
       {
-        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t78 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C12) {
+        if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && (#0#26#isSet ?{core::int} #0#26{core::int} : let final core::bool* #t78 = #0#26#isSet = true in #0#26 = #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}).{core::num::<=}(#C12){(core::num) → core::bool}) {
           #t58 = 21;
           break #L2;
         }
diff --git a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.strong.expect b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.strong.expect
index 2354b328576..3e2b42a3c86 100644
--- a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.strong.expect
+++ b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.strong.expect
@@ -123,7 +123,7 @@ static method exhaustive1a(core::List<core::num> list) → dynamic
     #L2:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t2 = 0;
           break #L2;
         }
@@ -144,7 +144,7 @@ static method exhaustive1b(core::List<core::num> list) → dynamic
     #L3:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t3 = 0;
           break #L3;
         }
@@ -165,7 +165,7 @@ static method exhaustive2a(core::List<core::num> list) → dynamic
     #L4:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t4 = 0;
           break #L4;
         }
@@ -192,7 +192,7 @@ static method exhaustive2b(core::List<core::num> list) → dynamic
     #L5:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t5 = 0;
           break #L5;
         }
@@ -219,7 +219,7 @@ static method exhaustive2c(core::List<core::num> list) → dynamic
     #L6:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t6 = 0;
           break #L6;
         }
@@ -274,7 +274,7 @@ static method nonExhaustive2aMissing(core::List<core::num> list) → dynamic
     #L9:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t9 = 0;
           break #L9;
         }
@@ -295,7 +295,7 @@ static method nonExhaustive2bMissing(core::List<core::num> list) → dynamic
     #L10:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t10 = 0;
           break #L10;
         }
@@ -316,7 +316,7 @@ static method nonExhaustive2cMissing(core::List<core::num> list) → dynamic
     #L11:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t11 = 0;
           break #L11;
         }
@@ -351,7 +351,7 @@ static method nonExhaustive1aRestrictedValue(core::List<core::num> list) → dyn
     #L13:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t13 = 0;
           break #L13;
         }
@@ -373,7 +373,7 @@ static method nonExhaustive1aRestrictedType(core::List<core::num> list) → dyna
     #L14:
     {
       {
-        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final dynamic #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final dynamic #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}).{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t14 = 0;
           break #L14;
         }
@@ -394,7 +394,7 @@ static method nonExhaustive1bRestrictedValue(core::List<core::num> list) → dyn
     #L15:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t17 = 0;
           break #L15;
         }
@@ -415,7 +415,7 @@ static method nonExhaustive1bRestrictedType(core::List<core::num> list) → dyna
     #L16:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t18 = 0;
           break #L16;
         }
@@ -436,7 +436,7 @@ static method nonExhaustive2aRestrictedValue(core::List<core::num> list) → dyn
     #L17:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t19 = 0;
           break #L17;
         }
@@ -463,7 +463,7 @@ static method nonExhaustive2bRestrictedValue(core::List<core::num> list) → dyn
     #L18:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t20 = 0;
           break #L18;
         }
@@ -490,7 +490,7 @@ static method nonExhaustive2cRestrictedValue(core::List<core::num> list) → dyn
     #L19:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t21 = 0;
           break #L19;
         }
@@ -517,7 +517,7 @@ static method nonExhaustive2dRestrictedValue(core::List<core::num> list) → dyn
     #L20:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t22 = 0;
           break #L20;
         }
@@ -544,7 +544,7 @@ static method nonExhaustive2eRestrictedValue(core::List<core::num> list) → dyn
     #L21:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t23 = 0;
           break #L21;
         }
@@ -571,7 +571,7 @@ static method nonExhaustive2fRestrictedValue(core::List<core::num> list) → dyn
     #L22:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t24 = 0;
           break #L22;
         }
diff --git a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.strong.transformed.expect
index 432607b2780..f4e8e83a8fd 100644
--- a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.strong.transformed.expect
@@ -125,7 +125,7 @@ static method exhaustive1a(core::List<core::num> list) → dynamic
     #L2:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t2 = 0;
           break #L2;
         }
@@ -148,7 +148,7 @@ static method exhaustive1b(core::List<core::num> list) → dynamic
     #L3:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t3 = 0;
           break #L3;
         }
@@ -171,7 +171,7 @@ static method exhaustive2a(core::List<core::num> list) → dynamic
     #L4:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t4 = 0;
           break #L4;
         }
@@ -200,7 +200,7 @@ static method exhaustive2b(core::List<core::num> list) → dynamic
     #L5:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t5 = 0;
           break #L5;
         }
@@ -229,7 +229,7 @@ static method exhaustive2c(core::List<core::num> list) → dynamic
     #L6:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t6 = 0;
           break #L6;
         }
@@ -286,7 +286,7 @@ static method nonExhaustive2aMissing(core::List<core::num> list) → dynamic
     #L9:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t9 = 0;
           break #L9;
         }
@@ -309,7 +309,7 @@ static method nonExhaustive2bMissing(core::List<core::num> list) → dynamic
     #L10:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t10 = 0;
           break #L10;
         }
@@ -332,7 +332,7 @@ static method nonExhaustive2cMissing(core::List<core::num> list) → dynamic
     #L11:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t11 = 0;
           break #L11;
         }
@@ -369,7 +369,7 @@ static method nonExhaustive1aRestrictedValue(core::List<core::num> list) → dyn
     #L13:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t13 = 0;
           break #L13;
         }
@@ -391,7 +391,7 @@ static method nonExhaustive1aRestrictedType(core::List<core::num> list) → dyna
     #L14:
     {
       {
-        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final core::bool* #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final core::bool* #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}).{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t14 = 0;
           break #L14;
         }
@@ -414,7 +414,7 @@ static method nonExhaustive1bRestrictedValue(core::List<core::num> list) → dyn
     #L15:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t17 = 0;
           break #L15;
         }
@@ -437,7 +437,7 @@ static method nonExhaustive1bRestrictedType(core::List<core::num> list) → dyna
     #L16:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t18 = 0;
           break #L16;
         }
@@ -460,7 +460,7 @@ static method nonExhaustive2aRestrictedValue(core::List<core::num> list) → dyn
     #L17:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t19 = 0;
           break #L17;
         }
@@ -489,7 +489,7 @@ static method nonExhaustive2bRestrictedValue(core::List<core::num> list) → dyn
     #L18:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t20 = 0;
           break #L18;
         }
@@ -518,7 +518,7 @@ static method nonExhaustive2cRestrictedValue(core::List<core::num> list) → dyn
     #L19:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t21 = 0;
           break #L19;
         }
@@ -547,7 +547,7 @@ static method nonExhaustive2dRestrictedValue(core::List<core::num> list) → dyn
     #L20:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t22 = 0;
           break #L20;
         }
@@ -576,7 +576,7 @@ static method nonExhaustive2eRestrictedValue(core::List<core::num> list) → dyn
     #L21:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t23 = 0;
           break #L21;
         }
@@ -605,7 +605,7 @@ static method nonExhaustive2fRestrictedValue(core::List<core::num> list) → dyn
     #L22:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t24 = 0;
           break #L22;
         }
diff --git a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.expect b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.expect
index e5d0b9b377c..7c9519a6cc3 100644
--- a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.expect
+++ b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.expect
@@ -125,7 +125,7 @@ static method exhaustive1a(core::List<core::num> list) → dynamic
     #L2:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t2 = 0;
           break #L2;
         }
@@ -147,7 +147,7 @@ static method exhaustive1b(core::List<core::num> list) → dynamic
     #L3:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t3 = 0;
           break #L3;
         }
@@ -169,7 +169,7 @@ static method exhaustive2a(core::List<core::num> list) → dynamic
     #L4:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t4 = 0;
           break #L4;
         }
@@ -197,7 +197,7 @@ static method exhaustive2b(core::List<core::num> list) → dynamic
     #L5:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t5 = 0;
           break #L5;
         }
@@ -225,7 +225,7 @@ static method exhaustive2c(core::List<core::num> list) → dynamic
     #L6:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t6 = 0;
           break #L6;
         }
@@ -283,7 +283,7 @@ static method nonExhaustive2aMissing(core::List<core::num> list) → dynamic
     #L9:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t9 = 0;
           break #L9;
         }
@@ -305,7 +305,7 @@ static method nonExhaustive2bMissing(core::List<core::num> list) → dynamic
     #L10:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t10 = 0;
           break #L10;
         }
@@ -327,7 +327,7 @@ static method nonExhaustive2cMissing(core::List<core::num> list) → dynamic
     #L11:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t11 = 0;
           break #L11;
         }
@@ -364,7 +364,7 @@ static method nonExhaustive1aRestrictedValue(core::List<core::num> list) → dyn
     #L13:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t13 = 0;
           break #L13;
         }
@@ -387,7 +387,7 @@ static method nonExhaustive1aRestrictedType(core::List<core::num> list) → dyna
     #L14:
     {
       {
-        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final dynamic #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final dynamic #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}).{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t14 = 0;
           break #L14;
         }
@@ -409,7 +409,7 @@ static method nonExhaustive1bRestrictedValue(core::List<core::num> list) → dyn
     #L15:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t17 = 0;
           break #L15;
         }
@@ -431,7 +431,7 @@ static method nonExhaustive1bRestrictedType(core::List<core::num> list) → dyna
     #L16:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t18 = 0;
           break #L16;
         }
@@ -453,7 +453,7 @@ static method nonExhaustive2aRestrictedValue(core::List<core::num> list) → dyn
     #L17:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t19 = 0;
           break #L17;
         }
@@ -481,7 +481,7 @@ static method nonExhaustive2bRestrictedValue(core::List<core::num> list) → dyn
     #L18:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t20 = 0;
           break #L18;
         }
@@ -509,7 +509,7 @@ static method nonExhaustive2cRestrictedValue(core::List<core::num> list) → dyn
     #L19:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t21 = 0;
           break #L19;
         }
@@ -537,7 +537,7 @@ static method nonExhaustive2dRestrictedValue(core::List<core::num> list) → dyn
     #L20:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t22 = 0;
           break #L20;
         }
@@ -565,7 +565,7 @@ static method nonExhaustive2eRestrictedValue(core::List<core::num> list) → dyn
     #L21:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t23 = 0;
           break #L21;
         }
@@ -593,7 +593,7 @@ static method nonExhaustive2fRestrictedValue(core::List<core::num> list) → dyn
     #L22:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t24 = 0;
           break #L22;
         }
diff --git a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.modular.expect
index e5d0b9b377c..7c9519a6cc3 100644
--- a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.modular.expect
@@ -125,7 +125,7 @@ static method exhaustive1a(core::List<core::num> list) → dynamic
     #L2:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t2 = 0;
           break #L2;
         }
@@ -147,7 +147,7 @@ static method exhaustive1b(core::List<core::num> list) → dynamic
     #L3:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t3 = 0;
           break #L3;
         }
@@ -169,7 +169,7 @@ static method exhaustive2a(core::List<core::num> list) → dynamic
     #L4:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t4 = 0;
           break #L4;
         }
@@ -197,7 +197,7 @@ static method exhaustive2b(core::List<core::num> list) → dynamic
     #L5:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t5 = 0;
           break #L5;
         }
@@ -225,7 +225,7 @@ static method exhaustive2c(core::List<core::num> list) → dynamic
     #L6:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t6 = 0;
           break #L6;
         }
@@ -283,7 +283,7 @@ static method nonExhaustive2aMissing(core::List<core::num> list) → dynamic
     #L9:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t9 = 0;
           break #L9;
         }
@@ -305,7 +305,7 @@ static method nonExhaustive2bMissing(core::List<core::num> list) → dynamic
     #L10:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t10 = 0;
           break #L10;
         }
@@ -327,7 +327,7 @@ static method nonExhaustive2cMissing(core::List<core::num> list) → dynamic
     #L11:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t11 = 0;
           break #L11;
         }
@@ -364,7 +364,7 @@ static method nonExhaustive1aRestrictedValue(core::List<core::num> list) → dyn
     #L13:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t13 = 0;
           break #L13;
         }
@@ -387,7 +387,7 @@ static method nonExhaustive1aRestrictedType(core::List<core::num> list) → dyna
     #L14:
     {
       {
-        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final dynamic #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final dynamic #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}).{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t14 = 0;
           break #L14;
         }
@@ -409,7 +409,7 @@ static method nonExhaustive1bRestrictedValue(core::List<core::num> list) → dyn
     #L15:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t17 = 0;
           break #L15;
         }
@@ -431,7 +431,7 @@ static method nonExhaustive1bRestrictedType(core::List<core::num> list) → dyna
     #L16:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t18 = 0;
           break #L16;
         }
@@ -453,7 +453,7 @@ static method nonExhaustive2aRestrictedValue(core::List<core::num> list) → dyn
     #L17:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t19 = 0;
           break #L17;
         }
@@ -481,7 +481,7 @@ static method nonExhaustive2bRestrictedValue(core::List<core::num> list) → dyn
     #L18:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t20 = 0;
           break #L18;
         }
@@ -509,7 +509,7 @@ static method nonExhaustive2cRestrictedValue(core::List<core::num> list) → dyn
     #L19:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t21 = 0;
           break #L19;
         }
@@ -537,7 +537,7 @@ static method nonExhaustive2dRestrictedValue(core::List<core::num> list) → dyn
     #L20:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t22 = 0;
           break #L20;
         }
@@ -565,7 +565,7 @@ static method nonExhaustive2eRestrictedValue(core::List<core::num> list) → dyn
     #L21:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t23 = 0;
           break #L21;
         }
@@ -593,7 +593,7 @@ static method nonExhaustive2fRestrictedValue(core::List<core::num> list) → dyn
     #L22:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t24 = 0;
           break #L22;
         }
diff --git a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.transformed.expect
index 520a09e8890..c252a6fe527 100644
--- a/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/patterns/exhaustiveness/list.dart.weak.transformed.expect
@@ -127,7 +127,7 @@ static method exhaustive1a(core::List<core::num> list) → dynamic
     #L2:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t2 = 0;
           break #L2;
         }
@@ -151,7 +151,7 @@ static method exhaustive1b(core::List<core::num> list) → dynamic
     #L3:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t3 = 0;
           break #L3;
         }
@@ -175,7 +175,7 @@ static method exhaustive2a(core::List<core::num> list) → dynamic
     #L4:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t4 = 0;
           break #L4;
         }
@@ -205,7 +205,7 @@ static method exhaustive2b(core::List<core::num> list) → dynamic
     #L5:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t5 = 0;
           break #L5;
         }
@@ -235,7 +235,7 @@ static method exhaustive2c(core::List<core::num> list) → dynamic
     #L6:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t6 = 0;
           break #L6;
         }
@@ -295,7 +295,7 @@ static method nonExhaustive2aMissing(core::List<core::num> list) → dynamic
     #L9:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t9 = 0;
           break #L9;
         }
@@ -319,7 +319,7 @@ static method nonExhaustive2bMissing(core::List<core::num> list) → dynamic
     #L10:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t10 = 0;
           break #L10;
         }
@@ -343,7 +343,7 @@ static method nonExhaustive2cMissing(core::List<core::num> list) → dynamic
     #L11:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t11 = 0;
           break #L11;
         }
@@ -382,7 +382,7 @@ static method nonExhaustive1aRestrictedValue(core::List<core::num> list) → dyn
     #L13:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t13 = 0;
           break #L13;
         }
@@ -405,7 +405,7 @@ static method nonExhaustive1aRestrictedType(core::List<core::num> list) → dyna
     #L14:
     {
       {
-        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final core::bool* #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}) =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#0 is{ForNonNullableByDefault} core::List<core::int> && (#0#2#isSet ?{core::int} #0#2{core::int} : let final core::bool* #t15 = #0#2#isSet = true in #0#2 = #0#0{core::List<core::int>}.{core::List::length}{core::int}).{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t14 = 0;
           break #L14;
         }
@@ -429,7 +429,7 @@ static method nonExhaustive1bRestrictedValue(core::List<core::num> list) → dyn
     #L15:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t17 = 0;
           break #L15;
         }
@@ -453,7 +453,7 @@ static method nonExhaustive1bRestrictedType(core::List<core::num> list) → dyna
     #L16:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t18 = 0;
           break #L16;
         }
@@ -477,7 +477,7 @@ static method nonExhaustive2aRestrictedValue(core::List<core::num> list) → dyn
     #L17:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t19 = 0;
           break #L17;
         }
@@ -507,7 +507,7 @@ static method nonExhaustive2bRestrictedValue(core::List<core::num> list) → dyn
     #L18:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t20 = 0;
           break #L18;
         }
@@ -537,7 +537,7 @@ static method nonExhaustive2cRestrictedValue(core::List<core::num> list) → dyn
     #L19:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t21 = 0;
           break #L19;
         }
@@ -567,7 +567,7 @@ static method nonExhaustive2dRestrictedValue(core::List<core::num> list) → dyn
     #L20:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t22 = 0;
           break #L20;
         }
@@ -597,7 +597,7 @@ static method nonExhaustive2eRestrictedValue(core::List<core::num> list) → dyn
     #L21:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t23 = 0;
           break #L21;
         }
@@ -627,7 +627,7 @@ static method nonExhaustive2fRestrictedValue(core::List<core::num> list) → dyn
     #L22:
     {
       {
-        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C1) {
+        if(#0#1.{core::num::<=}(#C1){(core::num) → core::bool}) {
           #t24 = 0;
           break #L22;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.strong.expect b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.strong.expect
index e065749c4c3..25f17c72074 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.strong.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.strong.expect
@@ -14,7 +14,7 @@ static method test(dynamic o) → dynamic {
   {
     final synthesized dynamic #0#0 = o;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
       }
     }
   }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.strong.transformed.expect
index e065749c4c3..25f17c72074 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.strong.transformed.expect
@@ -14,7 +14,7 @@ static method test(dynamic o) → dynamic {
   {
     final synthesized dynamic #0#0 = o;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
       }
     }
   }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.expect b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.expect
index e065749c4c3..25f17c72074 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.expect
@@ -14,7 +14,7 @@ static method test(dynamic o) → dynamic {
   {
     final synthesized dynamic #0#0 = o;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
       }
     }
   }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.modular.expect
index e065749c4c3..25f17c72074 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.modular.expect
@@ -14,7 +14,7 @@ static method test(dynamic o) → dynamic {
   {
     final synthesized dynamic #0#0 = o;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
       }
     }
   }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.transformed.expect
index e065749c4c3..25f17c72074 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_errors.dart.weak.transformed.expect
@@ -14,7 +14,7 @@ static method test(dynamic o) → dynamic {
   {
     final synthesized dynamic #0#0 = o;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<invalid-type> && #0#0{core::List<invalid-type>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
       }
     }
   }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.strong.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.strong.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.strong.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.strong.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.strong.transformed.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.strong.transformed.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.modular.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.modular.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.transformed.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty.dart.weak.transformed.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.strong.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.strong.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.strong.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.strong.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.strong.transformed.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.strong.transformed.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.modular.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.modular.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.transformed.expect
index 30b4b650d56..be6e8961738 100644
--- a/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/patterns/list_pattern_inside_case_empty_whitespace.dart.weak.transformed.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::List<dynamic> && #0#0{core::List<dynamic>}.{core::List::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.strong.expect b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.strong.expect
index 13259972d69..78c54e8395e 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.strong.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.strong.expect
@@ -17,7 +17,7 @@ static method test(dynamic o) → dynamic {
   #L1:
   {
     final synthesized dynamic #0#0 = o;
-    late final synthesized core::bool #0#4 = #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1;
+    late final synthesized core::bool #0#4 = #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool};
     {
       if(#0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4 || #0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4) {
       }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.strong.transformed.expect
index 7d3294f5173..74846fc0084 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.strong.transformed.expect
@@ -18,7 +18,7 @@ static method test(dynamic o) → dynamic {
   {
     final synthesized dynamic #0#0 = o;
     function ##0#4#initializer() → core::bool
-      return #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1;
+      return #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool};
     late final synthesized core::bool #0#4 = ##0#4#initializer(){() → core::bool};
     {
       if(#0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4 || #0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4) {
diff --git a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.expect b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.expect
index 13259972d69..78c54e8395e 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.expect
@@ -17,7 +17,7 @@ static method test(dynamic o) → dynamic {
   #L1:
   {
     final synthesized dynamic #0#0 = o;
-    late final synthesized core::bool #0#4 = #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1;
+    late final synthesized core::bool #0#4 = #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool};
     {
       if(#0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4 || #0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4) {
       }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.modular.expect
index 13259972d69..78c54e8395e 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.modular.expect
@@ -17,7 +17,7 @@ static method test(dynamic o) → dynamic {
   #L1:
   {
     final synthesized dynamic #0#0 = o;
-    late final synthesized core::bool #0#4 = #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1;
+    late final synthesized core::bool #0#4 = #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool};
     {
       if(#0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4 || #0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4) {
       }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.transformed.expect
index 7d3294f5173..74846fc0084 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_errors.dart.weak.transformed.expect
@@ -18,7 +18,7 @@ static method test(dynamic o) → dynamic {
   {
     final synthesized dynamic #0#0 = o;
     function ##0#4#initializer() → core::bool
-      return #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1;
+      return #0#0{core::Map<invalid-type, invalid-type>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool};
     late final synthesized core::bool #0#4 = ##0#4#initializer(){() → core::bool};
     {
       if(#0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4 || #0#0 is{ForNonNullableByDefault} core::Map<invalid-type, invalid-type> && #0#4) {
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.strong.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.strong.expect
index f021ad84c24..97d32bc7832 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.strong.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.strong.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.strong.transformed.expect
index f021ad84c24..97d32bc7832 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.strong.transformed.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.expect
index f021ad84c24..97d32bc7832 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.modular.expect
index f021ad84c24..97d32bc7832 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.modular.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.transformed.expect
index f021ad84c24..97d32bc7832 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_case_empty.dart.weak.transformed.expect
@@ -7,7 +7,7 @@ static method test(dynamic x) → dynamic {
   {
     final synthesized dynamic #0#0 = x;
     {
-      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C1) {
+      if(#0#0 is{ForNonNullableByDefault} core::Map<dynamic, dynamic> && #0#0{core::Map<dynamic, dynamic>}.{core::Map::length}{core::int}.{core::num::<=}(#C1){(core::num) → core::bool}) {
         {
           break #L1;
         }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.strong.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.strong.expect
index d976a00122a..57002f5722d 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.strong.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.strong.expect
@@ -33,7 +33,7 @@ static method test3(core::Map<core::bool, core::double> x) → dynamic {
   }
   {
     final synthesized core::Map<core::bool, core::double> #1#0 = x;
-    if(#1#0.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C9) {
+    if(#1#0.{core::Map::length}{core::int}.{core::num::<=}(#C9){(core::num) → core::bool}) {
     }
   }
 }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.strong.transformed.expect
index f5e6135f9cc..5264419dcec 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.strong.transformed.expect
@@ -33,7 +33,7 @@ static method test3(core::Map<core::bool, core::double> x) → dynamic {
   }
   {
     final synthesized core::Map<core::bool, core::double> #1#0 = x;
-    if(#1#0.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C9) {
+    if(#1#0.{core::Map::length}{core::int}.{core::num::<=}(#C9){(core::num) → core::bool}) {
     }
   }
 }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.expect
index d976a00122a..57002f5722d 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.expect
@@ -33,7 +33,7 @@ static method test3(core::Map<core::bool, core::double> x) → dynamic {
   }
   {
     final synthesized core::Map<core::bool, core::double> #1#0 = x;
-    if(#1#0.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C9) {
+    if(#1#0.{core::Map::length}{core::int}.{core::num::<=}(#C9){(core::num) → core::bool}) {
     }
   }
 }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.modular.expect
index d976a00122a..57002f5722d 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.modular.expect
@@ -33,7 +33,7 @@ static method test3(core::Map<core::bool, core::double> x) → dynamic {
   }
   {
     final synthesized core::Map<core::bool, core::double> #1#0 = x;
-    if(#1#0.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C9) {
+    if(#1#0.{core::Map::length}{core::int}.{core::num::<=}(#C9){(core::num) → core::bool}) {
     }
   }
 }
diff --git a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.transformed.expect
index f5e6135f9cc..5264419dcec 100644
--- a/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/patterns/map_pattern_inside_if_case.dart.weak.transformed.expect
@@ -33,7 +33,7 @@ static method test3(core::Map<core::bool, core::double> x) → dynamic {
   }
   {
     final synthesized core::Map<core::bool, core::double> #1#0 = x;
-    if(#1#0.{core::Map::length}{core::int} =={core::num::==}{(core::Object) → core::bool} #C9) {
+    if(#1#0.{core::Map::length}{core::int}.{core::num::<=}(#C9){(core::num) → core::bool}) {
     }
   }
 }
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart b/pkg/front_end/testcases/patterns/negative_length.dart
new file mode 100644
index 00000000000..8b011cc22f4
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart
@@ -0,0 +1,75 @@
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:collection';
+
+class NegativeLengthList<E> with ListMixin<E> {
+  final List<E> _list;
+
+  NegativeLengthList(this._list);
+
+  int get length => _list.length <= 0 ? -1 : _list.length;
+
+  void set length(int value) {
+    _list.length = value;
+  }
+
+  E operator [](int index) => _list[index];
+
+  void operator []=(int index, E value) {
+    _list[index] = value;
+  }
+}
+
+class NegativeLengthMap<K, V> with MapMixin<K, V> {
+  final Map<K, V> _map;
+
+  NegativeLengthMap(this._map);
+
+  int get length => _map.length <= 0 ? -1 : _map.length;
+
+  V? operator [](Object? key) => _map[key];
+
+  void operator []=(K key, V value) {
+    _map[key] = value;
+  }
+
+  Iterable<K> get keys => _map.keys;
+
+  V? remove(Object? key) => _map.remove(key);
+
+  void clear() => _map.clear();
+}
+
+int switchList(List<int> list) => switch (list) {
+      [_, _, ...] => 2,
+      [_] => 1,
+      [] => 0,
+    };
+
+int switchMap(Map<int, String> map) => switch (map) {
+      {0: _} => 1,
+      {} => 0,
+      {...} => 2,
+    };
+
+main() {
+  expect(0, switchList([]));
+  expect(1, switchList([0]));
+  expect(2, switchList([0, 1]));
+  expect(0, switchList(NegativeLengthList([])));
+  expect(1, switchList(NegativeLengthList([0])));
+  expect(2, switchList(NegativeLengthList([0, 1])));
+
+  expect(0, switchMap({}));
+  expect(1, switchMap({0: ''}));
+  expect(2, switchMap({1: ''}));
+  expect(0, switchMap(NegativeLengthMap({})));
+  expect(1, switchMap(NegativeLengthMap({0: ''})));
+  expect(2, switchMap(NegativeLengthMap({1: ''})));
+}
+
+expect(expected, actual) {
+  if (expected != actual) throw 'Expected $expected, actual $actual';
+}
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart.strong.expect b/pkg/front_end/testcases/patterns/negative_length.dart.strong.expect
new file mode 100644
index 00000000000..e5a7204f7a4
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart.strong.expect
@@ -0,0 +1,293 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+import "dart:math" as math;
+
+import "dart:collection";
+
+abstract class _NegativeLengthList&Object&ListMixin<E extends core::Object? = dynamic> = core::Object with col::ListMixin<self::_NegativeLengthList&Object&ListMixin::E%> /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthList&Object&ListMixin<self::_NegativeLengthList&Object&ListMixin::E%>
+    : super core::Object::•()
+    ;
+  mixin-super-stub get first() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::first};
+  mixin-super-stub set first(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void
+    return super.{col::ListMixin::first} = value;
+  mixin-super-stub get last() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::last};
+  mixin-super-stub set last(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void
+    return super.{col::ListMixin::last} = value;
+  mixin-super-stub get iterator() → core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::iterator};
+  mixin-super-stub method elementAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::elementAt}(index);
+  mixin-super-stub method followedBy(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::followedBy}(other);
+  mixin-super-stub method forEach((self::_NegativeLengthList&Object&ListMixin::E%) → void action) → void
+    return super.{col::ListMixin::forEach}(action);
+  mixin-super-stub get isEmpty() → core::bool
+    return super.{col::ListMixin::isEmpty};
+  mixin-super-stub get isNotEmpty() → core::bool
+    return super.{col::ListMixin::isNotEmpty};
+  mixin-super-stub get single() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::single};
+  mixin-super-stub method contains(core::Object? element) → core::bool
+    return super.{col::ListMixin::contains}(element);
+  mixin-super-stub method every((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool
+    return super.{col::ListMixin::every}(test);
+  mixin-super-stub method any((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool
+    return super.{col::ListMixin::any}(test);
+  mixin-super-stub method firstWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::firstWhere}(test, orElse: orElse);
+  mixin-super-stub method lastWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::lastWhere}(test, orElse: orElse);
+  mixin-super-stub method singleWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::singleWhere}(test, orElse: orElse);
+  mixin-super-stub method join([core::String separator = #C2]) → core::String
+    return super.{col::ListMixin::join}(separator);
+  mixin-super-stub method where((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::where}(test);
+  mixin-super-stub method whereType<T extends core::Object? = dynamic>() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::whereType::T%>
+    return super.{col::ListMixin::whereType}<self::_NegativeLengthList&Object&ListMixin::whereType::T%>();
+  mixin-super-stub method map<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::map::T% f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::map::T%>
+    return super.{col::ListMixin::map}<self::_NegativeLengthList&Object&ListMixin::map::T%>(f);
+  mixin-super-stub method expand<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%> f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%>
+    return super.{col::ListMixin::expand}<self::_NegativeLengthList&Object&ListMixin::expand::T%>(f);
+  mixin-super-stub method reduce(covariant-by-class (self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::E% combine) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::reduce}(combine);
+  mixin-super-stub method fold<T extends core::Object? = dynamic>(self::_NegativeLengthList&Object&ListMixin::fold::T% initialValue, (self::_NegativeLengthList&Object&ListMixin::fold::T%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::fold::T% combine) → self::_NegativeLengthList&Object&ListMixin::fold::T%
+    return super.{col::ListMixin::fold}<self::_NegativeLengthList&Object&ListMixin::fold::T%>(initialValue, combine);
+  mixin-super-stub method skip(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::skip}(count);
+  mixin-super-stub method skipWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::skipWhile}(test);
+  mixin-super-stub method take(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::take}(count);
+  mixin-super-stub method takeWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::takeWhile}(test);
+  mixin-super-stub method toList({core::bool growable = #C3}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::toList}(growable: growable);
+  mixin-super-stub method toSet() → core::Set<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::toSet}();
+  mixin-super-stub method add(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void
+    return super.{col::ListMixin::add}(element);
+  mixin-super-stub method addAll(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::addAll}(iterable);
+  mixin-super-stub method remove(core::Object? element) → core::bool
+    return super.{col::ListMixin::remove}(element);
+  mixin-super-stub method _closeGap(core::int start, core::int end) → void
+    return super.{col::ListMixin::_closeGap}(start, end);
+  mixin-super-stub method removeWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void
+    return super.{col::ListMixin::removeWhere}(test);
+  mixin-super-stub method retainWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void
+    return super.{col::ListMixin::retainWhere}(test);
+  mixin-super-stub method _filter((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, core::bool retainMatching) → void
+    return super.{col::ListMixin::_filter}(test, retainMatching);
+  mixin-super-stub method clear() → void
+    return super.{col::ListMixin::clear}();
+  mixin-super-stub method cast<R extends core::Object? = dynamic>() → core::List<self::_NegativeLengthList&Object&ListMixin::cast::R%>
+    return super.{col::ListMixin::cast}<self::_NegativeLengthList&Object&ListMixin::cast::R%>();
+  mixin-super-stub method removeLast() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::removeLast}();
+  mixin-super-stub method sort([(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) →? core::int compare = #C1]) → void
+    return super.{col::ListMixin::sort}(compare);
+  mixin-super-stub method shuffle([math::Random? random = #C1]) → void
+    return super.{col::ListMixin::shuffle}(random);
+  mixin-super-stub method asMap() → core::Map<core::int, self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::asMap}();
+  mixin-super-stub operator +(covariant-by-class core::List<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::+}(other);
+  mixin-super-stub method sublist(core::int start, [core::int? end = #C1]) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::sublist}(start, end);
+  mixin-super-stub method getRange(core::int start, core::int end) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::getRange}(start, end);
+  mixin-super-stub method removeRange(core::int start, core::int end) → void
+    return super.{col::ListMixin::removeRange}(start, end);
+  mixin-super-stub method fillRange(core::int start, core::int end, [covariant-by-class self::_NegativeLengthList&Object&ListMixin::E? fill = #C1]) → void
+    return super.{col::ListMixin::fillRange}(start, end, fill);
+  mixin-super-stub method setRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable, [core::int skipCount = #C4]) → void
+    return super.{col::ListMixin::setRange}(start, end, iterable, skipCount);
+  mixin-super-stub method replaceRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> newContents) → void
+    return super.{col::ListMixin::replaceRange}(start, end, newContents);
+  mixin-super-stub method indexOf(covariant-by-class core::Object? element, [core::int start = #C4]) → core::int
+    return super.{col::ListMixin::indexOf}(element, start);
+  mixin-super-stub method indexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int start = #C4]) → core::int
+    return super.{col::ListMixin::indexWhere}(test, start);
+  mixin-super-stub method lastIndexOf(covariant-by-class core::Object? element, [core::int? start = #C1]) → core::int
+    return super.{col::ListMixin::lastIndexOf}(element, start);
+  mixin-super-stub method lastIndexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int? start = #C1]) → core::int
+    return super.{col::ListMixin::lastIndexWhere}(test, start);
+  mixin-super-stub method insert(core::int index, covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void
+    return super.{col::ListMixin::insert}(index, element);
+  mixin-super-stub method removeAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::removeAt}(index);
+  mixin-super-stub method insertAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::insertAll}(index, iterable);
+  mixin-super-stub method setAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::setAll}(index, iterable);
+  mixin-super-stub get reversed() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::reversed};
+  mixin-super-stub method toString() → core::String
+    return super.{col::ListMixin::toString}();
+}
+class NegativeLengthList<E extends core::Object? = dynamic> extends self::_NegativeLengthList&Object&ListMixin<self::NegativeLengthList::E%> {
+  final field core::List<self::NegativeLengthList::E%> _list;
+  constructor •(core::List<self::NegativeLengthList::E%> _list) → self::NegativeLengthList<self::NegativeLengthList::E%>
+    : self::NegativeLengthList::_list = _list, super self::_NegativeLengthList&Object&ListMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int};
+  set length(core::int value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length} = value;
+  }
+  operator [](core::int index) → self::NegativeLengthList::E%
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]}(index){(core::int) → self::NegativeLengthList::E%};
+  operator []=(core::int index, covariant-by-class self::NegativeLengthList::E% value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]=}(index, value){(core::int, self::NegativeLengthList::E%) → void};
+  }
+}
+abstract class _NegativeLengthMap&Object&MapMixin<K extends core::Object? = dynamic, V extends core::Object? = dynamic> = core::Object with col::MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthMap&Object&MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>
+    : super core::Object::•()
+    ;
+  abstract mixin-stub operator [](core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?; -> col::MapMixin::[]
+  abstract mixin-stub operator []=(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class self::_NegativeLengthMap&Object&MapMixin::V% value) → void; -> col::MapMixin::[]=
+  abstract mixin-stub method remove(core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?; -> col::MapMixin::remove
+  abstract mixin-stub method clear() → void; -> col::MapMixin::clear
+  mixin-super-stub get length() → core::int
+    return super.{col::MapMixin::length};
+  abstract mixin-stub get keys() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>; -> col::MapMixin::keys
+  mixin-super-stub method cast<RK extends core::Object? = dynamic, RV extends core::Object? = dynamic>() → core::Map<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>
+    return super.{col::MapMixin::cast}<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>();
+  mixin-super-stub method forEach((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void action) → void
+    return super.{col::MapMixin::forEach}(action);
+  mixin-super-stub method addAll(covariant-by-class core::Map<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> other) → void
+    return super.{col::MapMixin::addAll}(other);
+  mixin-super-stub method containsValue(core::Object? value) → core::bool
+    return super.{col::MapMixin::containsValue}(value);
+  mixin-super-stub method putIfAbsent(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class () → self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent) → self::_NegativeLengthMap&Object&MapMixin::V%
+    return super.{col::MapMixin::putIfAbsent}(key, ifAbsent);
+  mixin-super-stub method update(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update, {covariant-by-class () →? self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent = #C1}) → self::_NegativeLengthMap&Object&MapMixin::V%
+    return super.{col::MapMixin::update}(key, update, ifAbsent: ifAbsent);
+  mixin-super-stub method updateAll(covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update) → void
+    return super.{col::MapMixin::updateAll}(update);
+  mixin-super-stub get entries() → core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>
+    return super.{col::MapMixin::entries};
+  mixin-super-stub method map<K2 extends core::Object? = dynamic, V2 extends core::Object? = dynamic>((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> transform) → core::Map<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>
+    return super.{col::MapMixin::map}<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>(transform);
+  mixin-super-stub method addEntries(covariant-by-class core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> newEntries) → void
+    return super.{col::MapMixin::addEntries}(newEntries);
+  mixin-super-stub method removeWhere((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::bool test) → void
+    return super.{col::MapMixin::removeWhere}(test);
+  mixin-super-stub method containsKey(core::Object? key) → core::bool
+    return super.{col::MapMixin::containsKey}(key);
+  mixin-super-stub get isEmpty() → core::bool
+    return super.{col::MapMixin::isEmpty};
+  mixin-super-stub get isNotEmpty() → core::bool
+    return super.{col::MapMixin::isNotEmpty};
+  mixin-super-stub get values() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::V%>
+    return super.{col::MapMixin::values};
+  mixin-super-stub method toString() → core::String
+    return super.{col::MapMixin::toString}();
+}
+class NegativeLengthMap<K extends core::Object? = dynamic, V extends core::Object? = dynamic> extends self::_NegativeLengthMap&Object&MapMixin<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> {
+  final field core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map;
+  constructor •(core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map) → self::NegativeLengthMap<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>
+    : self::NegativeLengthMap::_map = _map, super self::_NegativeLengthMap&Object&MapMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int};
+  operator [](core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  operator []=(covariant-by-class self::NegativeLengthMap::K% key, covariant-by-class self::NegativeLengthMap::V% value) → void {
+    this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]=}(key, value){(self::NegativeLengthMap::K%, self::NegativeLengthMap::V%) → void};
+  }
+  get keys() → core::Iterable<self::NegativeLengthMap::K%>
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::keys}{core::Iterable<self::NegativeLengthMap::K%>};
+  method remove(core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::remove}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  method clear() → void
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::clear}(){() → void};
+}
+static method switchList(core::List<core::int> list) → core::int
+  return block {
+    core::int #t1;
+    final synthesized core::List<core::int> #0#0 = list;
+    late final synthesized core::int #0#1 = #0#0.{core::List::length}{core::int};
+    #L1:
+    {
+      {
+        if(#0#1.{core::num::>=}(#C5){(core::num) → core::bool}) {
+          #t1 = 2;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C6) {
+          #t1 = 1;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C4){(core::num) → core::bool}) {
+          #t1 = 0;
+          break #L1;
+        }
+      }
+    }
+  } =>#t1;
+static method switchMap(core::Map<core::int, core::String> map) → core::int
+  return block {
+    core::int #t2;
+    final synthesized core::Map<core::int, core::String> #0#0 = map;
+    late final synthesized core::int #0#1 = #0#0.{core::Map::length}{core::int};
+    #L2:
+    {
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C6 && #0#0.{core::Map::containsKey}(#C4){(core::Object?) → core::bool} && (let final dynamic #t3 = #0#0.{core::Map::[]}(#C4){(core::Object?) → core::String?} in true)) {
+          #t2 = 1;
+          break #L2;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C4){(core::num) → core::bool}) {
+          #t2 = 0;
+          break #L2;
+        }
+      }
+      {
+        if(true) {
+          #t2 = 2;
+          break #L2;
+        }
+      }
+    }
+  } =>#t2;
+static method main() → dynamic {
+  self::expect(0, self::switchList(<core::int>[]));
+  self::expect(1, self::switchList(<core::int>[0]));
+  self::expect(2, self::switchList(<core::int>[0, 1]));
+  self::expect(0, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[])));
+  self::expect(1, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[0])));
+  self::expect(2, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[0, 1])));
+  self::expect(0, self::switchMap(<core::int, core::String>{}));
+  self::expect(1, self::switchMap(<core::int, core::String>{0: ""}));
+  self::expect(2, self::switchMap(<core::int, core::String>{1: ""}));
+  self::expect(0, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{})));
+  self::expect(1, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{0: ""})));
+  self::expect(2, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{1: ""})));
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!(expected =={core::Object::==}{(core::Object) → core::bool} actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = null
+  #C2 = ""
+  #C3 = true
+  #C4 = 0
+  #C5 = 2
+  #C6 = 1
+}
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart.strong.transformed.expect b/pkg/front_end/testcases/patterns/negative_length.dart.strong.transformed.expect
new file mode 100644
index 00000000000..19213cee2cd
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart.strong.transformed.expect
@@ -0,0 +1,781 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+import "dart:_internal" as _in;
+import "dart:math" as math;
+
+import "dart:collection";
+
+abstract class _NegativeLengthList&Object&ListMixin<E extends core::Object? = dynamic> extends core::Object implements col::ListMixin<self::_NegativeLengthList&Object&ListMixin::E%> /*isAnonymousMixin,isEliminatedMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthList&Object&ListMixin<self::_NegativeLengthList&Object&ListMixin::E%>
+    : super core::Object::•()
+    ;
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ first() → self::_NegativeLengthList&Object&ListMixin::E% {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    return this.{core::List::[]}(0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+  }
+  set /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ first(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    this.{core::List::[]=}(0, value){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+  }
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ last() → self::_NegativeLengthList&Object&ListMixin::E% {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    return this.{core::List::[]}(this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int}){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+  }
+  set /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ last(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    this.{core::List::[]=}(this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int}, value){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+  }
+  @#C3
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ iterator() → core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::ListIterator::•<self::_NegativeLengthList&Object&ListMixin::E%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ elementAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return this.{core::List::[]}(index){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ followedBy(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return _in::FollowedByIterable::firstEfficient<self::_NegativeLengthList&Object&ListMixin::E%>(this, other);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ forEach((self::_NegativeLengthList&Object&ListMixin::E%) → void action) → void {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      action(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+  }
+  @#C3
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ isEmpty() → core::bool
+    return this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0;
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ isNotEmpty() → core::bool
+    return !this.{col::ListMixin::isEmpty}{core::bool};
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ single() → self::_NegativeLengthList&Object&ListMixin::E% {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    if(this.{core::List::length}{core::int}.{core::num::>}(1){(core::num) → core::bool})
+      throw _in::IterableElementError::tooMany();
+    return this.{core::List::[]}(0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ contains(core::Object? element) → core::bool {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%} =={core::Object::==}{(core::Object) → core::bool} element)
+        return true;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return false;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ every((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(!test(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return false;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return true;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ any((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(test(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return true;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return false;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ firstWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C2}) → self::_NegativeLengthList&Object&ListMixin::E% {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      self::_NegativeLengthList&Object&ListMixin::E% element = this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(test(element){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return element;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    if(!(orElse == null))
+      return orElse{() → self::_NegativeLengthList&Object&ListMixin::E%}(){() → self::_NegativeLengthList&Object&ListMixin::E%};
+    throw _in::IterableElementError::noElement();
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ lastWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C2}) → self::_NegativeLengthList&Object&ListMixin::E% {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = length.{core::num::-}(1){(core::num) → core::int}; i.{core::num::>=}(0){(core::num) → core::bool}; i = i.{core::num::-}(1){(core::num) → core::int}) {
+      self::_NegativeLengthList&Object&ListMixin::E% element = this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(test(element){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return element;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    if(!(orElse == null))
+      return orElse{() → self::_NegativeLengthList&Object&ListMixin::E%}(){() → self::_NegativeLengthList&Object&ListMixin::E%};
+    throw _in::IterableElementError::noElement();
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ singleWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C2}) → self::_NegativeLengthList&Object&ListMixin::E% {
+    core::int length = this.{core::List::length}{core::int};
+    late self::_NegativeLengthList&Object&ListMixin::E% match;
+    core::bool matchFound = false;
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      self::_NegativeLengthList&Object&ListMixin::E% element = this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(test(element){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool}) {
+        if(matchFound) {
+          throw _in::IterableElementError::tooMany();
+        }
+        matchFound = true;
+        match = element;
+      }
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    if(matchFound)
+      return match;
+    if(!(orElse == null))
+      return orElse{() → self::_NegativeLengthList&Object&ListMixin::E%}(){() → self::_NegativeLengthList&Object&ListMixin::E%};
+    throw _in::IterableElementError::noElement();
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ join([core::String separator = #C4]) → core::String {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      return "";
+    core::StringBuffer buffer = let final core::StringBuffer #t1 = new core::StringBuffer::•() in block {
+      #t1.{core::StringBuffer::writeAll}(this, separator){(core::Iterable<dynamic>, [core::String]) → void};
+    } =>#t1;
+    return buffer.{core::StringBuffer::toString}(){() → core::String};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ where((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::WhereIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, test);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ whereType<T extends core::Object? = dynamic>() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::whereType::T%>
+    return new _in::WhereTypeIterable::•<self::_NegativeLengthList&Object&ListMixin::whereType::T%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ map<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::map::T% f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::map::T%>
+    return new _in::MappedListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::map::T%>(this, f);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ expand<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%> f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%>
+    return new _in::ExpandIterable::•<self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::expand::T%>(this, f);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ reduce(covariant-by-class (self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::E% combine) → self::_NegativeLengthList&Object&ListMixin::E% {
+    core::int length = this.{core::List::length}{core::int};
+    if(length =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    self::_NegativeLengthList&Object&ListMixin::E% value = this.{core::List::[]}(0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+    for (core::int i = 1; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      value = combine(value, this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return value;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ fold<T extends core::Object? = dynamic>(self::_NegativeLengthList&Object&ListMixin::fold::T% initialValue, (self::_NegativeLengthList&Object&ListMixin::fold::T%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::fold::T% combine) → self::_NegativeLengthList&Object&ListMixin::fold::T% {
+    self::_NegativeLengthList&Object&ListMixin::fold::T% value = initialValue;
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      value = combine(value, this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::fold::T%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::fold::T%};
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return value;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ skip(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::SubListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, count, null);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ skipWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> {
+    return new _in::SkipWhileIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, test);
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ take(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::SubListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, 0, _in::checkNotNullable<core::int>(count, "count"));
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ takeWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> {
+    return new _in::TakeWhileIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, test);
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ toList({core::bool growable = #C5}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%> {
+    if(this.{col::ListMixin::isEmpty}{core::bool})
+      return core::List::empty<self::_NegativeLengthList&Object&ListMixin::E%>(growable: growable);
+    self::_NegativeLengthList&Object&ListMixin::E% first = this.{core::List::[]}(0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+    core::List<self::_NegativeLengthList&Object&ListMixin::E%> result = core::List::filled<self::_NegativeLengthList&Object&ListMixin::E%>(this.{core::List::length}{core::int}, first, growable: growable);
+    for (core::int i = 1; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      result.{core::List::[]=}(i, this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ toSet() → core::Set<self::_NegativeLengthList&Object&ListMixin::E%> {
+    core::Set<self::_NegativeLengthList&Object&ListMixin::E%> result = new col::_Set::•<self::_NegativeLengthList&Object&ListMixin::E%>();
+    for (core::int i = 0; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      result.{core::Set::add}(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool};
+    }
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ add(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void {
+    this.{core::List::[]=}(let final core::int #t2 = this.{core::List::length}{core::int} in let final core::int #t3 = this.{core::List::length} = #t2.{core::num::+}(1){(core::num) → core::int} in #t2, element){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ addAll(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void {
+    core::int i = this.{core::List::length}{core::int};
+    {
+      synthesized core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%> :sync-for-iterator = iterable.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthList&Object&ListMixin::E% element = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthList&Object&ListMixin::E%};
+        {
+          assert(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} i || (throw new core::ConcurrentModificationError::•(this)));
+          this.{col::ListMixin::add}(element){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+          i = i.{core::num::+}(1){(core::num) → core::int};
+        }
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ remove(core::Object? element) → core::bool {
+    for (core::int i = 0; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%} =={core::Object::==}{(core::Object) → core::bool} element) {
+        this.{col::ListMixin::_closeGap}(i, i.{core::num::+}(1){(core::num) → core::int}){(core::int, core::int) → void};
+        return true;
+      }
+    }
+    return false;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ _closeGap(core::int start, core::int end) → void {
+    core::int length = this.{core::List::length}{core::int};
+    assert(0.{core::num::<=}(start){(core::num) → core::bool});
+    assert(start.{core::num::<}(end){(core::num) → core::bool});
+    assert(end.{core::num::<=}(length){(core::num) → core::bool});
+    core::int size = end.{core::num::-}(start){(core::num) → core::int};
+    for (core::int i = end; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      this.{core::List::[]=}(i.{core::num::-}(size){(core::num) → core::int}, this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+    this.{core::List::length} = length.{core::num::-}(size){(core::num) → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ removeWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void {
+    this.{col::ListMixin::_filter}(test, false){((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool, core::bool) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ retainWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void {
+    this.{col::ListMixin::_filter}(test, true){((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool, core::bool) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ _filter((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, core::bool retainMatching) → void {
+    core::List<self::_NegativeLengthList&Object&ListMixin::E%> retained = core::_GrowableList::•<self::_NegativeLengthList&Object&ListMixin::E%>(0);
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      self::_NegativeLengthList&Object&ListMixin::E% element = this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(test(element){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool} =={core::Object::==}{(core::Object) → core::bool} retainMatching) {
+        retained.{core::List::add}(element){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      }
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    if(!(retained.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+      this.{col::ListMixin::setRange}(0, retained.{core::List::length}{core::int}, retained){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+      this.{core::List::length} = retained.{core::List::length}{core::int};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ clear() → void {
+    this.{core::List::length} = 0;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ cast<R extends core::Object? = dynamic>() → core::List<self::_NegativeLengthList&Object&ListMixin::cast::R%>
+    return core::List::castFrom<self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::cast::R%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ removeLast() → self::_NegativeLengthList&Object&ListMixin::E% {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0) {
+      throw _in::IterableElementError::noElement();
+    }
+    self::_NegativeLengthList&Object&ListMixin::E% result = this.{core::List::[]}(this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int}){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+    this.{core::List::length} = this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int};
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ sort([(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) →? core::int compare = #C2]) → void {
+    _in::Sort::sort<self::_NegativeLengthList&Object&ListMixin::E%>(this, let final (self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) →? core::int #t4 = compare in #t4 == null ?{(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → core::int} #C6 : #t4{(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → core::int});
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ shuffle([math::Random? random = #C2]) → void {
+    random == null ?{math::Random} random = math::Random::•() : null;
+    if(random{math::Random} == null)
+      throw "!";
+    core::int length = this.{core::List::length}{core::int};
+    while (length.{core::num::>}(1){(core::num) → core::bool}) {
+      core::int pos = random{math::Random}.{math::Random::nextInt}(length){(core::int) → core::int};
+      length = length.{core::num::-}(1){(core::num) → core::int};
+      self::_NegativeLengthList&Object&ListMixin::E% tmp = this.{core::List::[]}(length){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      this.{core::List::[]=}(length, this.{core::List::[]}(pos){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      this.{core::List::[]=}(pos, tmp){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ asMap() → core::Map<core::int, self::_NegativeLengthList&Object&ListMixin::E%> {
+    return new _in::ListMapView::•<self::_NegativeLengthList&Object&ListMixin::E%>(this);
+  }
+  operator /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ +(covariant-by-class core::List<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return block {
+      final core::List<self::_NegativeLengthList&Object&ListMixin::E%> #t5 = core::List::of<self::_NegativeLengthList&Object&ListMixin::E%>(this);
+      #t5.{core::List::addAll}{Invariant}(other){(core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>) → void};
+    } =>#t5;
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ sublist(core::int start, [core::int? end = #C2]) → core::List<self::_NegativeLengthList&Object&ListMixin::E%> {
+    core::int listLength = this.{core::List::length}{core::int};
+    end == null ?{core::int} end = listLength : null;
+    if(end{core::int} == null)
+      throw "!";
+    core::RangeError::checkValidRange(start, end{core::int}, listLength);
+    return core::List::from<self::_NegativeLengthList&Object&ListMixin::E%>(this.{col::ListMixin::getRange}(start, end{core::int}){(core::int, core::int) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>});
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ getRange(core::int start, core::int end) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> {
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    return new _in::SubListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, start, end);
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ removeRange(core::int start, core::int end) → void {
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    if(end.{core::num::>}(start){(core::num) → core::bool}) {
+      this.{col::ListMixin::_closeGap}(start, end){(core::int, core::int) → void};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ fillRange(core::int start, core::int end, [covariant-by-class self::_NegativeLengthList&Object&ListMixin::E? fill = #C2]) → void {
+    self::_NegativeLengthList&Object&ListMixin::E% value = let self::_NegativeLengthList&Object&ListMixin::E? #t6 = fill in #t6 == null ?{self::_NegativeLengthList&Object&ListMixin::E%} let self::_NegativeLengthList&Object&ListMixin::E? #t7 = #t6 in #t7 == null ?{self::_NegativeLengthList&Object&ListMixin::E%} #t7 as{ForNonNullableByDefault} self::_NegativeLengthList&Object&ListMixin::E% : #t7{self::_NegativeLengthList&Object&ListMixin::E%} : #t6{self::_NegativeLengthList&Object&ListMixin::E%};
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    for (core::int i = start; i.{core::num::<}(end){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      this.{core::List::[]=}(i, value){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ setRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable, [core::int skipCount = #C7]) → void {
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    core::int length = end.{core::num::-}(start){(core::num) → core::int};
+    if(length =={core::num::==}{(core::Object) → core::bool} 0)
+      return;
+    core::RangeError::checkNotNegative(skipCount, "skipCount");
+    core::List<self::_NegativeLengthList&Object&ListMixin::E%> otherList;
+    core::int otherStart;
+    if(iterable is{ForNonNullableByDefault} core::List<self::_NegativeLengthList&Object&ListMixin::E%>) {
+      otherList = iterable{core::List<self::_NegativeLengthList&Object&ListMixin::E%>};
+      otherStart = skipCount;
+    }
+    else {
+      otherList = iterable.{core::Iterable::skip}(skipCount){(core::int) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>}.{core::Iterable::toList}(growable: false){({growable: core::bool}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>};
+      otherStart = 0;
+    }
+    if(otherStart.{core::num::+}(length){(core::num) → core::int}.{core::num::>}(otherList.{core::List::length}{core::int}){(core::num) → core::bool}) {
+      throw _in::IterableElementError::tooFew();
+    }
+    if(otherStart.{core::num::<}(start){(core::num) → core::bool}) {
+      for (core::int i = length.{core::num::-}(1){(core::num) → core::int}; i.{core::num::>=}(0){(core::num) → core::bool}; i = i.{core::num::-}(1){(core::num) → core::int}) {
+        this.{core::List::[]=}(start.{core::num::+}(i){(core::num) → core::int}, otherList.{core::List::[]}(otherStart.{core::num::+}(i){(core::num) → core::int}){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      }
+    }
+    else {
+      for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+        this.{core::List::[]=}(start.{core::num::+}(i){(core::num) → core::int}, otherList.{core::List::[]}(otherStart.{core::num::+}(i){(core::num) → core::int}){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ replaceRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> newContents) → void {
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    if(start =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int}) {
+      this.{col::ListMixin::addAll}(newContents){(core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>) → void};
+      return;
+    }
+    if(!(newContents is{ForNonNullableByDefault} _in::EfficientLengthIterable<dynamic>)) {
+      newContents = newContents.{core::Iterable::toList}(){({growable: core::bool}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>};
+    }
+    core::int removeLength = end.{core::num::-}(start){(core::num) → core::int};
+    core::int insertLength = newContents.{core::Iterable::length}{core::int};
+    if(removeLength.{core::num::>=}(insertLength){(core::num) → core::bool}) {
+      core::int insertEnd = start.{core::num::+}(insertLength){(core::num) → core::int};
+      this.{col::ListMixin::setRange}(start, insertEnd, newContents){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+      if(removeLength.{core::num::>}(insertLength){(core::num) → core::bool}) {
+        this.{col::ListMixin::_closeGap}(insertEnd, end){(core::int, core::int) → void};
+      }
+    }
+    else
+      if(end =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int}) {
+        core::int i = start;
+        {
+          synthesized core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%> :sync-for-iterator = newContents.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>};
+          for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+            self::_NegativeLengthList&Object&ListMixin::E% element = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthList&Object&ListMixin::E%};
+            {
+              if(i.{core::num::<}(end){(core::num) → core::bool}) {
+                this.{core::List::[]=}(i, element){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+              }
+              else {
+                this.{col::ListMixin::add}(element){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+              }
+              i = i.{core::num::+}(1){(core::num) → core::int};
+            }
+          }
+        }
+      }
+      else {
+        core::int delta = insertLength.{core::num::-}(removeLength){(core::num) → core::int};
+        core::int oldLength = this.{core::List::length}{core::int};
+        core::int insertEnd = start.{core::num::+}(insertLength){(core::num) → core::int};
+        for (core::int i = oldLength.{core::num::-}(delta){(core::num) → core::int}; i.{core::num::<}(oldLength){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+          this.{col::ListMixin::add}(this.{core::List::[]}(i.{core::num::>}(0){(core::num) → core::bool} ?{core::int} i : 0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+        }
+        if(insertEnd.{core::num::<}(oldLength){(core::num) → core::bool}) {
+          this.{col::ListMixin::setRange}(insertEnd, oldLength, this, end){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+        }
+        this.{col::ListMixin::setRange}(start, insertEnd, newContents){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+      }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ indexOf(covariant-by-class core::Object? element, [core::int start = #C7]) → core::int {
+    if(start.{core::num::<}(0){(core::num) → core::bool})
+      start = 0;
+    for (core::int i = start; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%} =={core::Object::==}{(core::Object) → core::bool} element)
+        return i;
+    }
+    return 1.{core::int::unary-}(){() → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ indexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int start = #C7]) → core::int {
+    if(start.{core::num::<}(0){(core::num) → core::bool})
+      start = 0;
+    for (core::int i = start; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(test(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return i;
+    }
+    return 1.{core::int::unary-}(){() → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ lastIndexOf(covariant-by-class core::Object? element, [core::int? start = #C2]) → core::int {
+    if(start == null || start{core::int}.{core::num::>=}(this.{core::List::length}{core::int}){(core::num) → core::bool})
+      start = this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int};
+    if(start{core::int} == null)
+      throw "!";
+    for (core::int i = start{core::int}; i.{core::num::>=}(0){(core::num) → core::bool}; i = i.{core::num::-}(1){(core::num) → core::int}) {
+      if(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%} =={core::Object::==}{(core::Object) → core::bool} element)
+        return i;
+    }
+    return 1.{core::int::unary-}(){() → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ lastIndexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int? start = #C2]) → core::int {
+    if(start == null || start{core::int}.{core::num::>=}(this.{core::List::length}{core::int}){(core::num) → core::bool})
+      start = this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int};
+    if(start{core::int} == null)
+      throw "!";
+    for (core::int i = start{core::int}; i.{core::num::>=}(0){(core::num) → core::bool}; i = i.{core::num::-}(1){(core::num) → core::int}) {
+      if(test(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return i;
+    }
+    return 1.{core::int::unary-}(){() → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ insert(core::int index, covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void {
+    _in::checkNotNullable<core::int>(index, "index");
+    core::int length = this.{core::List::length}{core::int};
+    core::RangeError::checkValueInInterval(index, 0, length, "index");
+    this.{col::ListMixin::add}(element){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    if(!(index =={core::num::==}{(core::Object) → core::bool} length)) {
+      this.{col::ListMixin::setRange}(index.{core::num::+}(1){(core::num) → core::int}, length.{core::num::+}(1){(core::num) → core::int}, this, index){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+      this.{core::List::[]=}(index, element){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ removeAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E% {
+    self::_NegativeLengthList&Object&ListMixin::E% result = this.{core::List::[]}(index){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+    this.{col::ListMixin::_closeGap}(index, index.{core::num::+}(1){(core::num) → core::int}){(core::int, core::int) → void};
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ insertAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void {
+    core::RangeError::checkValueInInterval(index, 0, this.{core::List::length}{core::int}, "index");
+    if(index =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int}) {
+      this.{col::ListMixin::addAll}(iterable){(core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>) → void};
+      return;
+    }
+    if(!(iterable is{ForNonNullableByDefault} _in::EfficientLengthIterable<dynamic>) || core::identical(iterable, this)) {
+      iterable = iterable.{core::Iterable::toList}(){({growable: core::bool}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>};
+    }
+    core::int insertionLength = iterable.{core::Iterable::length}{core::int};
+    if(insertionLength =={core::num::==}{(core::Object) → core::bool} 0) {
+      return;
+    }
+    core::int oldLength = this.{core::List::length}{core::int};
+    for (core::int i = oldLength.{core::num::-}(insertionLength){(core::num) → core::int}; i.{core::num::<}(oldLength){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      this.{col::ListMixin::add}(this.{core::List::[]}(i.{core::num::>}(0){(core::num) → core::bool} ?{core::int} i : 0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+    if(!(iterable.{core::Iterable::length}{core::int} =={core::num::==}{(core::Object) → core::bool} insertionLength)) {
+      this.{core::List::length} = this.{core::List::length}{core::int}.{core::num::-}(insertionLength){(core::num) → core::int};
+      throw new core::ConcurrentModificationError::•(iterable);
+    }
+    core::int oldCopyStart = index.{core::num::+}(insertionLength){(core::num) → core::int};
+    if(oldCopyStart.{core::num::<}(oldLength){(core::num) → core::bool}) {
+      this.{col::ListMixin::setRange}(oldCopyStart, oldLength, this, index){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+    }
+    this.{col::ListMixin::setAll}(index, iterable){(core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ setAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void {
+    if(iterable is{ForNonNullableByDefault} core::List<dynamic>) {
+      this.{col::ListMixin::setRange}(index, index.{core::num::+}(iterable.{core::Iterable::length}{core::int}){(core::num) → core::int}, iterable){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+    }
+    else {
+      {
+        synthesized core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%> :sync-for-iterator = iterable.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>};
+        for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+          self::_NegativeLengthList&Object&ListMixin::E% element = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthList&Object&ListMixin::E%};
+          {
+            this.{core::List::[]=}(let final core::int #t8 = index in let final core::int #t9 = index = #t8.{core::num::+}(1){(core::num) → core::int} in #t8, element){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+          }
+        }
+      }
+    }
+  }
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ reversed() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::ReversedListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ toString() → core::String
+    return col::IterableBase::iterableToFullString(this, "[", "]");
+  static method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ _compareAny(dynamic a, dynamic b) → core::int {
+    return core::Comparable::compare(a as{ForNonNullableByDefault} core::Comparable<dynamic>, b as{ForNonNullableByDefault} core::Comparable<dynamic>);
+  }
+}
+class NegativeLengthList<E extends core::Object? = dynamic> extends self::_NegativeLengthList&Object&ListMixin<self::NegativeLengthList::E%> {
+  final field core::List<self::NegativeLengthList::E%> _list;
+  constructor •(core::List<self::NegativeLengthList::E%> _list) → self::NegativeLengthList<self::NegativeLengthList::E%>
+    : self::NegativeLengthList::_list = _list, super self::_NegativeLengthList&Object&ListMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int};
+  set length(core::int value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length} = value;
+  }
+  operator [](core::int index) → self::NegativeLengthList::E%
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]}(index){(core::int) → self::NegativeLengthList::E%};
+  operator []=(core::int index, covariant-by-class self::NegativeLengthList::E% value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]=}(index, value){(core::int, self::NegativeLengthList::E%) → void};
+  }
+}
+abstract class _NegativeLengthMap&Object&MapMixin<K extends core::Object? = dynamic, V extends core::Object? = dynamic> extends core::Object implements col::MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> /*isAnonymousMixin,isEliminatedMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthMap&Object&MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>
+    : super core::Object::•()
+    ;
+  abstract operator /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ [](core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?;
+  abstract operator /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ []=(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class self::_NegativeLengthMap&Object&MapMixin::V% value) → void;
+  abstract method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ remove(core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?;
+  abstract method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ clear() → void;
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ length() → core::int
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::length}{core::int};
+  abstract get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ keys() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>;
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ cast<RK extends core::Object? = dynamic, RV extends core::Object? = dynamic>() → core::Map<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>
+    return core::Map::castFrom<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%, self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ forEach((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void action) → void {
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          action(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t10 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t10 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} let self::_NegativeLengthMap&Object&MapMixin::V? #t11 = #t10 in #t11 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t11 as{ForNonNullableByDefault} self::_NegativeLengthMap&Object&MapMixin::V% : #t11{self::_NegativeLengthMap&Object&MapMixin::V%} : #t10{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void};
+        }
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ addAll(covariant-by-class core::Map<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> other) → void {
+    other.{core::Map::forEach}((self::_NegativeLengthMap&Object&MapMixin::K% key, self::_NegativeLengthMap&Object&MapMixin::V% value) → void {
+      this.{col::MapMixin::[]=}(key, value){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void};
+    }){((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ containsValue(core::Object? value) → core::bool {
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          if(this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} =={core::Object::==}{(core::Object) → core::bool} value)
+            return true;
+        }
+      }
+    }
+    return false;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ putIfAbsent(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class () → self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent) → self::_NegativeLengthMap&Object&MapMixin::V% {
+    if(this.{col::MapMixin::containsKey}(key){(core::Object?) → core::bool}) {
+      return let self::_NegativeLengthMap&Object&MapMixin::V? #t12 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t12 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} let self::_NegativeLengthMap&Object&MapMixin::V? #t13 = #t12 in #t13 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t13 as{ForNonNullableByDefault} self::_NegativeLengthMap&Object&MapMixin::V% : #t13{self::_NegativeLengthMap&Object&MapMixin::V%} : #t12{self::_NegativeLengthMap&Object&MapMixin::V%};
+    }
+    return let final self::_NegativeLengthMap&Object&MapMixin::K% #t14 = key in let final self::_NegativeLengthMap&Object&MapMixin::V% #t15 = ifAbsent(){() → self::_NegativeLengthMap&Object&MapMixin::V%} in let final void #t16 = this.{col::MapMixin::[]=}(#t14, #t15){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void} in #t15;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ update(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update, {covariant-by-class () →? self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent = #C2}) → self::_NegativeLengthMap&Object&MapMixin::V% {
+    if(this.{col::MapMixin::containsKey}(key){(core::Object?) → core::bool}) {
+      return let final self::_NegativeLengthMap&Object&MapMixin::K% #t17 = key in let final self::_NegativeLengthMap&Object&MapMixin::V% #t18 = update(let self::_NegativeLengthMap&Object&MapMixin::V? #t19 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t19 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} let self::_NegativeLengthMap&Object&MapMixin::V? #t20 = #t19 in #t20 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t20 as{ForNonNullableByDefault} self::_NegativeLengthMap&Object&MapMixin::V% : #t20{self::_NegativeLengthMap&Object&MapMixin::V%} : #t19{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V%} in let final void #t21 = this.{col::MapMixin::[]=}(#t17, #t18){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void} in #t18;
+    }
+    if(!(ifAbsent == null)) {
+      return let final self::_NegativeLengthMap&Object&MapMixin::K% #t22 = key in let final self::_NegativeLengthMap&Object&MapMixin::V% #t23 = ifAbsent{() → self::_NegativeLengthMap&Object&MapMixin::V%}(){() → self::_NegativeLengthMap&Object&MapMixin::V%} in let final void #t24 = this.{col::MapMixin::[]=}(#t22, #t23){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void} in #t23;
+    }
+    throw new core::ArgumentError::value(key, "key", "Key not in map.");
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ updateAll(covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update) → void {
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          this.{col::MapMixin::[]=}(key, update(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t25 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t25 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} let self::_NegativeLengthMap&Object&MapMixin::V? #t26 = #t25 in #t26 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t26 as{ForNonNullableByDefault} self::_NegativeLengthMap&Object&MapMixin::V% : #t26{self::_NegativeLengthMap&Object&MapMixin::V%} : #t25{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void};
+        }
+      }
+    }
+  }
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ entries() → core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> {
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::map}<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>((self::_NegativeLengthMap&Object&MapMixin::K% key) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> => new core::MapEntry::_<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t27 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t27 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} let self::_NegativeLengthMap&Object&MapMixin::V? #t28 = #t27 in #t28 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t28 as{ForNonNullableByDefault} self::_NegativeLengthMap&Object&MapMixin::V% : #t28{self::_NegativeLengthMap&Object&MapMixin::V%} : #t27{self::_NegativeLengthMap&Object&MapMixin::V%})){((self::_NegativeLengthMap&Object&MapMixin::K%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>) → core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ map<K2 extends core::Object? = dynamic, V2 extends core::Object? = dynamic>((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> transform) → core::Map<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> {
+    core::Map<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> result = <self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>{};
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> entry = transform(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t29 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t29 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} let self::_NegativeLengthMap&Object&MapMixin::V? #t30 = #t29 in #t30 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t30 as{ForNonNullableByDefault} self::_NegativeLengthMap&Object&MapMixin::V% : #t30{self::_NegativeLengthMap&Object&MapMixin::V%} : #t29{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>};
+          result.{core::Map::[]=}(entry.{core::MapEntry::key}{self::_NegativeLengthMap&Object&MapMixin::map::K2%}, entry.{core::MapEntry::value}{self::_NegativeLengthMap&Object&MapMixin::map::V2%}){(self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%) → void};
+        }
+      }
+    }
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ addEntries(covariant-by-class core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> newEntries) → void {
+    {
+      synthesized core::Iterator<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> :sync-for-iterator = newEntries.{core::Iterable::iterator}{core::Iterator<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> entry = :sync-for-iterator.{core::Iterator::current}{core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>};
+        {
+          this.{col::MapMixin::[]=}(entry.{core::MapEntry::key}{self::_NegativeLengthMap&Object&MapMixin::K%}, entry.{core::MapEntry::value}{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void};
+        }
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ removeWhere((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::bool test) → void {
+    core::List<self::_NegativeLengthMap&Object&MapMixin::K%> keysToRemove = core::_GrowableList::•<self::_NegativeLengthMap&Object&MapMixin::K%>(0);
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          if(test(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t31 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t31 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} let self::_NegativeLengthMap&Object&MapMixin::V? #t32 = #t31 in #t32 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t32 as{ForNonNullableByDefault} self::_NegativeLengthMap&Object&MapMixin::V% : #t32{self::_NegativeLengthMap&Object&MapMixin::V%} : #t31{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::bool})
+            keysToRemove.{core::List::add}(key){(self::_NegativeLengthMap&Object&MapMixin::K%) → void};
+        }
+      }
+    }
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = keysToRemove.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          this.{col::MapMixin::remove}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?};
+        }
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ containsKey(core::Object? key) → core::bool
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::contains}(key){(core::Object?) → core::bool};
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ isEmpty() → core::bool
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::isEmpty}{core::bool};
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ isNotEmpty() → core::bool
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::isNotEmpty}{core::bool};
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ values() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::V%>
+    return new col::_MapBaseValueIterable::•<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ toString() → core::String
+    return col::MapBase::mapToString(this);
+}
+class NegativeLengthMap<K extends core::Object? = dynamic, V extends core::Object? = dynamic> extends self::_NegativeLengthMap&Object&MapMixin<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> {
+  final field core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map;
+  constructor •(core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map) → self::NegativeLengthMap<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>
+    : self::NegativeLengthMap::_map = _map, super self::_NegativeLengthMap&Object&MapMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int};
+  operator [](core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  operator []=(covariant-by-class self::NegativeLengthMap::K% key, covariant-by-class self::NegativeLengthMap::V% value) → void {
+    this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]=}(key, value){(self::NegativeLengthMap::K%, self::NegativeLengthMap::V%) → void};
+  }
+  get keys() → core::Iterable<self::NegativeLengthMap::K%>
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::keys}{core::Iterable<self::NegativeLengthMap::K%>};
+  method remove(core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::remove}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  method clear() → void
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::clear}(){() → void};
+}
+static method switchList(core::List<core::int> list) → core::int
+  return block {
+    core::int #t33;
+    final synthesized core::List<core::int> #0#0 = list;
+    function ##0#1#initializer() → core::int
+      return #0#0.{core::List::length}{core::int};
+    late final synthesized core::int #0#1 = ##0#1#initializer(){() → core::int};
+    #L1:
+    {
+      {
+        if(#0#1.{core::num::>=}(#C8){(core::num) → core::bool}) {
+          #t33 = 2;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C9) {
+          #t33 = 1;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C7){(core::num) → core::bool}) {
+          #t33 = 0;
+          break #L1;
+        }
+      }
+    }
+  } =>#t33;
+static method switchMap(core::Map<core::int, core::String> map) → core::int
+  return block {
+    core::int #t34;
+    final synthesized core::Map<core::int, core::String> #0#0 = map;
+    function ##0#1#initializer() → core::int
+      return #0#0.{core::Map::length}{core::int};
+    late final synthesized core::int #0#1 = ##0#1#initializer(){() → core::int};
+    #L2:
+    {
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C9 && #0#0.{core::Map::containsKey}(#C7){(core::Object?) → core::bool} && (let final core::String? #t35 = #0#0.{core::Map::[]}(#C7){(core::Object?) → core::String?} in true)) {
+          #t34 = 1;
+          break #L2;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C7){(core::num) → core::bool}) {
+          #t34 = 0;
+          break #L2;
+        }
+      }
+      {
+        if(true) {
+          #t34 = 2;
+          break #L2;
+        }
+      }
+    }
+  } =>#t34;
+static method main() → dynamic {
+  self::expect(0, self::switchList(core::_GrowableList::•<core::int>(0)));
+  self::expect(1, self::switchList(core::_GrowableList::_literal1<core::int>(0)));
+  self::expect(2, self::switchList(core::_GrowableList::_literal2<core::int>(0, 1)));
+  self::expect(0, self::switchList(new self::NegativeLengthList::•<core::int>(core::_GrowableList::•<core::int>(0))));
+  self::expect(1, self::switchList(new self::NegativeLengthList::•<core::int>(core::_GrowableList::_literal1<core::int>(0))));
+  self::expect(2, self::switchList(new self::NegativeLengthList::•<core::int>(core::_GrowableList::_literal2<core::int>(0, 1))));
+  self::expect(0, self::switchMap(<core::int, core::String>{}));
+  self::expect(1, self::switchMap(<core::int, core::String>{0: ""}));
+  self::expect(2, self::switchMap(<core::int, core::String>{1: ""}));
+  self::expect(0, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{})));
+  self::expect(1, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{0: ""})));
+  self::expect(2, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{1: ""})));
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!(expected =={core::Object::==}{(core::Object) → core::bool} actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = "vm:prefer-inline"
+  #C2 = null
+  #C3 = core::pragma {name:#C1, options:#C2}
+  #C4 = ""
+  #C5 = true
+  #C6 = static-tearoff col::ListMixin::_compareAny
+  #C7 = 0
+  #C8 = 2
+  #C9 = 1
+}
+
+Extra constant evaluation status:
+Evaluated: InstanceInvocation @ org-dartlang-sdk:///sdk/lib/collection/list.dart:492:12 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-sdk:///sdk/lib/collection/list.dart:500:12 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-sdk:///sdk/lib/collection/list.dart:512:12 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-sdk:///sdk/lib/collection/list.dart:524:12 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-testcase:///negative_length.dart:12:41 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-testcase:///negative_length.dart:30:40 -> IntConstant(-1)
+Extra constant evaluation: evaluated: 1467, effectively constant: 6
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart.textual_outline.expect b/pkg/front_end/testcases/patterns/negative_length.dart.textual_outline.expect
new file mode 100644
index 00000000000..db190db98c5
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart.textual_outline.expect
@@ -0,0 +1,26 @@
+import 'dart:collection';
+
+class NegativeLengthList<E> with ListMixin<E> {
+  final List<E> _list;
+  NegativeLengthList(this._list);
+  int get length => _list.length <= 0 ? -1 : _list.length;
+  void set length(int value) {}
+  E operator [](int index) => _list[index];
+  void operator []=(int index, E value) {}
+}
+
+class NegativeLengthMap<K, V> with MapMixin<K, V> {
+  final Map<K, V> _map;
+  NegativeLengthMap(this._map);
+  int get length => _map.length <= 0 ? -1 : _map.length;
+  V? operator [](Object? key) => _map[key];
+  void operator []=(K key, V value) {}
+  Iterable<K> get keys => _map.keys;
+  V? remove(Object? key) => _map.remove(key);
+  void clear() => _map.clear();
+}
+
+int switchList(List<int> list) => switch (list) {  };
+int switchMap(Map<int, String> map) => switch (map) {  };
+main() {}
+expect(expected, actual) {}
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/patterns/negative_length.dart.textual_outline_modelled.expect
new file mode 100644
index 00000000000..8450adb3a08
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart.textual_outline_modelled.expect
@@ -0,0 +1,31 @@
+import 'dart:collection';
+class NegativeLengthList<E> with ListMixin<E> {
+  E operator [](int index) => _list[index];
+  NegativeLengthList(this._list);
+  final List<E> _list;
+  int get length => _list.length <= 0 ? -1 : _list.length;
+  void operator []=(int index, E value) {}
+  void set length(int value) {}
+}
+class NegativeLengthMap<K, V> with MapMixin<K, V> {
+  Iterable<K> get keys => _map.keys;
+  NegativeLengthMap(this._map);
+  V? operator [](Object? key) => _map[key];
+  V? remove(Object? key) => _map.remove(key);
+  final Map<K, V> _map;
+  int get length => _map.length <= 0 ? -1 : _map.length;
+  void clear() => _map.clear();
+  void operator []=(K key, V value) {}
+}
+int switchList(List<int> list) => 
+switch (list) {}
+---- unknown chunk starts ----
+;
+---- unknown chunk ends ----
+int switchMap(Map<int, String> map) => 
+switch (map) {}
+---- unknown chunk starts ----
+;
+---- unknown chunk ends ----
+expect(expected, actual) {}
+main() {}
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart.weak.expect b/pkg/front_end/testcases/patterns/negative_length.dart.weak.expect
new file mode 100644
index 00000000000..535529a79f6
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart.weak.expect
@@ -0,0 +1,296 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+import "dart:math" as math;
+import "dart:_internal" as _in;
+
+import "dart:collection";
+
+abstract class _NegativeLengthList&Object&ListMixin<E extends core::Object? = dynamic> = core::Object with col::ListMixin<self::_NegativeLengthList&Object&ListMixin::E%> /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthList&Object&ListMixin<self::_NegativeLengthList&Object&ListMixin::E%>
+    : super core::Object::•()
+    ;
+  mixin-super-stub get first() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::first};
+  mixin-super-stub set first(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void
+    return super.{col::ListMixin::first} = value;
+  mixin-super-stub get last() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::last};
+  mixin-super-stub set last(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void
+    return super.{col::ListMixin::last} = value;
+  mixin-super-stub get iterator() → core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::iterator};
+  mixin-super-stub method elementAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::elementAt}(index);
+  mixin-super-stub method followedBy(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::followedBy}(other);
+  mixin-super-stub method forEach((self::_NegativeLengthList&Object&ListMixin::E%) → void action) → void
+    return super.{col::ListMixin::forEach}(action);
+  mixin-super-stub get isEmpty() → core::bool
+    return super.{col::ListMixin::isEmpty};
+  mixin-super-stub get isNotEmpty() → core::bool
+    return super.{col::ListMixin::isNotEmpty};
+  mixin-super-stub get single() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::single};
+  mixin-super-stub method contains(core::Object? element) → core::bool
+    return super.{col::ListMixin::contains}(element);
+  mixin-super-stub method every((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool
+    return super.{col::ListMixin::every}(test);
+  mixin-super-stub method any((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool
+    return super.{col::ListMixin::any}(test);
+  mixin-super-stub method firstWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::firstWhere}(test, orElse: orElse);
+  mixin-super-stub method lastWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::lastWhere}(test, orElse: orElse);
+  mixin-super-stub method singleWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::singleWhere}(test, orElse: orElse);
+  mixin-super-stub method join([core::String separator = #C2]) → core::String
+    return super.{col::ListMixin::join}(separator);
+  mixin-super-stub method where((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::where}(test);
+  mixin-super-stub method whereType<T extends core::Object? = dynamic>() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::whereType::T%>
+    return super.{col::ListMixin::whereType}<self::_NegativeLengthList&Object&ListMixin::whereType::T%>();
+  mixin-super-stub method map<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::map::T% f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::map::T%>
+    return super.{col::ListMixin::map}<self::_NegativeLengthList&Object&ListMixin::map::T%>(f);
+  mixin-super-stub method expand<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%> f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%>
+    return super.{col::ListMixin::expand}<self::_NegativeLengthList&Object&ListMixin::expand::T%>(f);
+  mixin-super-stub method reduce(covariant-by-class (self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::E% combine) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::reduce}(combine);
+  mixin-super-stub method fold<T extends core::Object? = dynamic>(self::_NegativeLengthList&Object&ListMixin::fold::T% initialValue, (self::_NegativeLengthList&Object&ListMixin::fold::T%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::fold::T% combine) → self::_NegativeLengthList&Object&ListMixin::fold::T%
+    return super.{col::ListMixin::fold}<self::_NegativeLengthList&Object&ListMixin::fold::T%>(initialValue, combine);
+  mixin-super-stub method skip(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::skip}(count);
+  mixin-super-stub method skipWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::skipWhile}(test);
+  mixin-super-stub method take(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::take}(count);
+  mixin-super-stub method takeWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::takeWhile}(test);
+  mixin-super-stub method toList({core::bool growable = #C3}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::toList}(growable: growable);
+  mixin-super-stub method toSet() → core::Set<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::toSet}();
+  mixin-super-stub method add(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void
+    return super.{col::ListMixin::add}(element);
+  mixin-super-stub method addAll(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::addAll}(iterable);
+  mixin-super-stub method remove(core::Object? element) → core::bool
+    return super.{col::ListMixin::remove}(element);
+  mixin-super-stub method _closeGap(core::int start, core::int end) → void
+    return super.{col::ListMixin::_closeGap}(start, end);
+  mixin-super-stub method removeWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void
+    return super.{col::ListMixin::removeWhere}(test);
+  mixin-super-stub method retainWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void
+    return super.{col::ListMixin::retainWhere}(test);
+  mixin-super-stub method _filter((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, core::bool retainMatching) → void
+    return super.{col::ListMixin::_filter}(test, retainMatching);
+  mixin-super-stub method clear() → void
+    return super.{col::ListMixin::clear}();
+  mixin-super-stub method cast<R extends core::Object? = dynamic>() → core::List<self::_NegativeLengthList&Object&ListMixin::cast::R%>
+    return super.{col::ListMixin::cast}<self::_NegativeLengthList&Object&ListMixin::cast::R%>();
+  mixin-super-stub method removeLast() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::removeLast}();
+  mixin-super-stub method sort([(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) →? core::int compare = #C1]) → void
+    return super.{col::ListMixin::sort}(compare);
+  mixin-super-stub method shuffle([math::Random? random = #C1]) → void
+    return super.{col::ListMixin::shuffle}(random);
+  mixin-super-stub method asMap() → core::Map<core::int, self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::asMap}();
+  mixin-super-stub operator +(covariant-by-class core::List<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::+}(other);
+  mixin-super-stub method sublist(core::int start, [core::int? end = #C1]) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::sublist}(start, end);
+  mixin-super-stub method getRange(core::int start, core::int end) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::getRange}(start, end);
+  mixin-super-stub method removeRange(core::int start, core::int end) → void
+    return super.{col::ListMixin::removeRange}(start, end);
+  mixin-super-stub method fillRange(core::int start, core::int end, [covariant-by-class self::_NegativeLengthList&Object&ListMixin::E? fill = #C1]) → void
+    return super.{col::ListMixin::fillRange}(start, end, fill);
+  mixin-super-stub method setRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable, [core::int skipCount = #C4]) → void
+    return super.{col::ListMixin::setRange}(start, end, iterable, skipCount);
+  mixin-super-stub method replaceRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> newContents) → void
+    return super.{col::ListMixin::replaceRange}(start, end, newContents);
+  mixin-super-stub method indexOf(covariant-by-class core::Object? element, [core::int start = #C4]) → core::int
+    return super.{col::ListMixin::indexOf}(element, start);
+  mixin-super-stub method indexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int start = #C4]) → core::int
+    return super.{col::ListMixin::indexWhere}(test, start);
+  mixin-super-stub method lastIndexOf(covariant-by-class core::Object? element, [core::int? start = #C1]) → core::int
+    return super.{col::ListMixin::lastIndexOf}(element, start);
+  mixin-super-stub method lastIndexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int? start = #C1]) → core::int
+    return super.{col::ListMixin::lastIndexWhere}(test, start);
+  mixin-super-stub method insert(core::int index, covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void
+    return super.{col::ListMixin::insert}(index, element);
+  mixin-super-stub method removeAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::removeAt}(index);
+  mixin-super-stub method insertAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::insertAll}(index, iterable);
+  mixin-super-stub method setAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::setAll}(index, iterable);
+  mixin-super-stub get reversed() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::reversed};
+  mixin-super-stub method toString() → core::String
+    return super.{col::ListMixin::toString}();
+}
+class NegativeLengthList<E extends core::Object? = dynamic> extends self::_NegativeLengthList&Object&ListMixin<self::NegativeLengthList::E%> {
+  final field core::List<self::NegativeLengthList::E%> _list;
+  constructor •(core::List<self::NegativeLengthList::E%> _list) → self::NegativeLengthList<self::NegativeLengthList::E%>
+    : self::NegativeLengthList::_list = _list, super self::_NegativeLengthList&Object&ListMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int};
+  set length(core::int value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length} = value;
+  }
+  operator [](core::int index) → self::NegativeLengthList::E%
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]}(index){(core::int) → self::NegativeLengthList::E%};
+  operator []=(core::int index, covariant-by-class self::NegativeLengthList::E% value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]=}(index, value){(core::int, self::NegativeLengthList::E%) → void};
+  }
+}
+abstract class _NegativeLengthMap&Object&MapMixin<K extends core::Object? = dynamic, V extends core::Object? = dynamic> = core::Object with col::MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthMap&Object&MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>
+    : super core::Object::•()
+    ;
+  abstract mixin-stub operator [](core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?; -> col::MapMixin::[]
+  abstract mixin-stub operator []=(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class self::_NegativeLengthMap&Object&MapMixin::V% value) → void; -> col::MapMixin::[]=
+  abstract mixin-stub method remove(core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?; -> col::MapMixin::remove
+  abstract mixin-stub method clear() → void; -> col::MapMixin::clear
+  mixin-super-stub get length() → core::int
+    return super.{col::MapMixin::length};
+  abstract mixin-stub get keys() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>; -> col::MapMixin::keys
+  mixin-super-stub method cast<RK extends core::Object? = dynamic, RV extends core::Object? = dynamic>() → core::Map<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>
+    return super.{col::MapMixin::cast}<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>();
+  mixin-super-stub method forEach((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void action) → void
+    return super.{col::MapMixin::forEach}(action);
+  mixin-super-stub method addAll(covariant-by-class core::Map<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> other) → void
+    return super.{col::MapMixin::addAll}(other);
+  mixin-super-stub method containsValue(core::Object? value) → core::bool
+    return super.{col::MapMixin::containsValue}(value);
+  mixin-super-stub method putIfAbsent(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class () → self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent) → self::_NegativeLengthMap&Object&MapMixin::V%
+    return super.{col::MapMixin::putIfAbsent}(key, ifAbsent);
+  mixin-super-stub method update(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update, {covariant-by-class () →? self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent = #C1}) → self::_NegativeLengthMap&Object&MapMixin::V%
+    return super.{col::MapMixin::update}(key, update, ifAbsent: ifAbsent);
+  mixin-super-stub method updateAll(covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update) → void
+    return super.{col::MapMixin::updateAll}(update);
+  mixin-super-stub get entries() → core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>
+    return super.{col::MapMixin::entries};
+  mixin-super-stub method map<K2 extends core::Object? = dynamic, V2 extends core::Object? = dynamic>((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> transform) → core::Map<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>
+    return super.{col::MapMixin::map}<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>(transform);
+  mixin-super-stub method addEntries(covariant-by-class core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> newEntries) → void
+    return super.{col::MapMixin::addEntries}(newEntries);
+  mixin-super-stub method removeWhere((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::bool test) → void
+    return super.{col::MapMixin::removeWhere}(test);
+  mixin-super-stub method containsKey(core::Object? key) → core::bool
+    return super.{col::MapMixin::containsKey}(key);
+  mixin-super-stub get isEmpty() → core::bool
+    return super.{col::MapMixin::isEmpty};
+  mixin-super-stub get isNotEmpty() → core::bool
+    return super.{col::MapMixin::isNotEmpty};
+  mixin-super-stub get values() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::V%>
+    return super.{col::MapMixin::values};
+  mixin-super-stub method toString() → core::String
+    return super.{col::MapMixin::toString}();
+}
+class NegativeLengthMap<K extends core::Object? = dynamic, V extends core::Object? = dynamic> extends self::_NegativeLengthMap&Object&MapMixin<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> {
+  final field core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map;
+  constructor •(core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map) → self::NegativeLengthMap<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>
+    : self::NegativeLengthMap::_map = _map, super self::_NegativeLengthMap&Object&MapMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int};
+  operator [](core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  operator []=(covariant-by-class self::NegativeLengthMap::K% key, covariant-by-class self::NegativeLengthMap::V% value) → void {
+    this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]=}(key, value){(self::NegativeLengthMap::K%, self::NegativeLengthMap::V%) → void};
+  }
+  get keys() → core::Iterable<self::NegativeLengthMap::K%>
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::keys}{core::Iterable<self::NegativeLengthMap::K%>};
+  method remove(core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::remove}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  method clear() → void
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::clear}(){() → void};
+}
+static method switchList(core::List<core::int> list) → core::int
+  return block {
+    core::int #t1;
+    final synthesized core::List<core::int> #0#0 = list;
+    late final synthesized core::int #0#1 = #0#0.{core::List::length}{core::int};
+    #L1:
+    {
+      {
+        if(#0#1.{core::num::>=}(#C5){(core::num) → core::bool}) {
+          #t1 = 2;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C6) {
+          #t1 = 1;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C4){(core::num) → core::bool}) {
+          #t1 = 0;
+          break #L1;
+        }
+      }
+      throw new _in::ReachabilityError::•("`null` encountered as case in a switch expression with a non-nullable type.");
+    }
+  } =>#t1;
+static method switchMap(core::Map<core::int, core::String> map) → core::int
+  return block {
+    core::int #t2;
+    final synthesized core::Map<core::int, core::String> #0#0 = map;
+    late final synthesized core::int #0#1 = #0#0.{core::Map::length}{core::int};
+    #L2:
+    {
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C6 && #0#0.{core::Map::containsKey}(#C4){(core::Object?) → core::bool} && (let final dynamic #t3 = #0#0.{core::Map::[]}(#C4){(core::Object?) → core::String?} in true)) {
+          #t2 = 1;
+          break #L2;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C4){(core::num) → core::bool}) {
+          #t2 = 0;
+          break #L2;
+        }
+      }
+      {
+        if(true) {
+          #t2 = 2;
+          break #L2;
+        }
+      }
+      throw new _in::ReachabilityError::•("`null` encountered as case in a switch expression with a non-nullable type.");
+    }
+  } =>#t2;
+static method main() → dynamic {
+  self::expect(0, self::switchList(<core::int>[]));
+  self::expect(1, self::switchList(<core::int>[0]));
+  self::expect(2, self::switchList(<core::int>[0, 1]));
+  self::expect(0, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[])));
+  self::expect(1, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[0])));
+  self::expect(2, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[0, 1])));
+  self::expect(0, self::switchMap(<core::int, core::String>{}));
+  self::expect(1, self::switchMap(<core::int, core::String>{0: ""}));
+  self::expect(2, self::switchMap(<core::int, core::String>{1: ""}));
+  self::expect(0, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{})));
+  self::expect(1, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{0: ""})));
+  self::expect(2, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{1: ""})));
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!(expected =={core::Object::==}{(core::Object) → core::bool} actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = null
+  #C2 = ""
+  #C3 = true
+  #C4 = 0
+  #C5 = 2
+  #C6 = 1
+}
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart.weak.modular.expect b/pkg/front_end/testcases/patterns/negative_length.dart.weak.modular.expect
new file mode 100644
index 00000000000..535529a79f6
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart.weak.modular.expect
@@ -0,0 +1,296 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+import "dart:math" as math;
+import "dart:_internal" as _in;
+
+import "dart:collection";
+
+abstract class _NegativeLengthList&Object&ListMixin<E extends core::Object? = dynamic> = core::Object with col::ListMixin<self::_NegativeLengthList&Object&ListMixin::E%> /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthList&Object&ListMixin<self::_NegativeLengthList&Object&ListMixin::E%>
+    : super core::Object::•()
+    ;
+  mixin-super-stub get first() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::first};
+  mixin-super-stub set first(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void
+    return super.{col::ListMixin::first} = value;
+  mixin-super-stub get last() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::last};
+  mixin-super-stub set last(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void
+    return super.{col::ListMixin::last} = value;
+  mixin-super-stub get iterator() → core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::iterator};
+  mixin-super-stub method elementAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::elementAt}(index);
+  mixin-super-stub method followedBy(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::followedBy}(other);
+  mixin-super-stub method forEach((self::_NegativeLengthList&Object&ListMixin::E%) → void action) → void
+    return super.{col::ListMixin::forEach}(action);
+  mixin-super-stub get isEmpty() → core::bool
+    return super.{col::ListMixin::isEmpty};
+  mixin-super-stub get isNotEmpty() → core::bool
+    return super.{col::ListMixin::isNotEmpty};
+  mixin-super-stub get single() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::single};
+  mixin-super-stub method contains(core::Object? element) → core::bool
+    return super.{col::ListMixin::contains}(element);
+  mixin-super-stub method every((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool
+    return super.{col::ListMixin::every}(test);
+  mixin-super-stub method any((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool
+    return super.{col::ListMixin::any}(test);
+  mixin-super-stub method firstWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::firstWhere}(test, orElse: orElse);
+  mixin-super-stub method lastWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::lastWhere}(test, orElse: orElse);
+  mixin-super-stub method singleWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C1}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::singleWhere}(test, orElse: orElse);
+  mixin-super-stub method join([core::String separator = #C2]) → core::String
+    return super.{col::ListMixin::join}(separator);
+  mixin-super-stub method where((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::where}(test);
+  mixin-super-stub method whereType<T extends core::Object? = dynamic>() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::whereType::T%>
+    return super.{col::ListMixin::whereType}<self::_NegativeLengthList&Object&ListMixin::whereType::T%>();
+  mixin-super-stub method map<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::map::T% f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::map::T%>
+    return super.{col::ListMixin::map}<self::_NegativeLengthList&Object&ListMixin::map::T%>(f);
+  mixin-super-stub method expand<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%> f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%>
+    return super.{col::ListMixin::expand}<self::_NegativeLengthList&Object&ListMixin::expand::T%>(f);
+  mixin-super-stub method reduce(covariant-by-class (self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::E% combine) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::reduce}(combine);
+  mixin-super-stub method fold<T extends core::Object? = dynamic>(self::_NegativeLengthList&Object&ListMixin::fold::T% initialValue, (self::_NegativeLengthList&Object&ListMixin::fold::T%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::fold::T% combine) → self::_NegativeLengthList&Object&ListMixin::fold::T%
+    return super.{col::ListMixin::fold}<self::_NegativeLengthList&Object&ListMixin::fold::T%>(initialValue, combine);
+  mixin-super-stub method skip(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::skip}(count);
+  mixin-super-stub method skipWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::skipWhile}(test);
+  mixin-super-stub method take(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::take}(count);
+  mixin-super-stub method takeWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::takeWhile}(test);
+  mixin-super-stub method toList({core::bool growable = #C3}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::toList}(growable: growable);
+  mixin-super-stub method toSet() → core::Set<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::toSet}();
+  mixin-super-stub method add(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void
+    return super.{col::ListMixin::add}(element);
+  mixin-super-stub method addAll(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::addAll}(iterable);
+  mixin-super-stub method remove(core::Object? element) → core::bool
+    return super.{col::ListMixin::remove}(element);
+  mixin-super-stub method _closeGap(core::int start, core::int end) → void
+    return super.{col::ListMixin::_closeGap}(start, end);
+  mixin-super-stub method removeWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void
+    return super.{col::ListMixin::removeWhere}(test);
+  mixin-super-stub method retainWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void
+    return super.{col::ListMixin::retainWhere}(test);
+  mixin-super-stub method _filter((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, core::bool retainMatching) → void
+    return super.{col::ListMixin::_filter}(test, retainMatching);
+  mixin-super-stub method clear() → void
+    return super.{col::ListMixin::clear}();
+  mixin-super-stub method cast<R extends core::Object? = dynamic>() → core::List<self::_NegativeLengthList&Object&ListMixin::cast::R%>
+    return super.{col::ListMixin::cast}<self::_NegativeLengthList&Object&ListMixin::cast::R%>();
+  mixin-super-stub method removeLast() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::removeLast}();
+  mixin-super-stub method sort([(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) →? core::int compare = #C1]) → void
+    return super.{col::ListMixin::sort}(compare);
+  mixin-super-stub method shuffle([math::Random? random = #C1]) → void
+    return super.{col::ListMixin::shuffle}(random);
+  mixin-super-stub method asMap() → core::Map<core::int, self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::asMap}();
+  mixin-super-stub operator +(covariant-by-class core::List<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::+}(other);
+  mixin-super-stub method sublist(core::int start, [core::int? end = #C1]) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::sublist}(start, end);
+  mixin-super-stub method getRange(core::int start, core::int end) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::getRange}(start, end);
+  mixin-super-stub method removeRange(core::int start, core::int end) → void
+    return super.{col::ListMixin::removeRange}(start, end);
+  mixin-super-stub method fillRange(core::int start, core::int end, [covariant-by-class self::_NegativeLengthList&Object&ListMixin::E? fill = #C1]) → void
+    return super.{col::ListMixin::fillRange}(start, end, fill);
+  mixin-super-stub method setRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable, [core::int skipCount = #C4]) → void
+    return super.{col::ListMixin::setRange}(start, end, iterable, skipCount);
+  mixin-super-stub method replaceRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> newContents) → void
+    return super.{col::ListMixin::replaceRange}(start, end, newContents);
+  mixin-super-stub method indexOf(covariant-by-class core::Object? element, [core::int start = #C4]) → core::int
+    return super.{col::ListMixin::indexOf}(element, start);
+  mixin-super-stub method indexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int start = #C4]) → core::int
+    return super.{col::ListMixin::indexWhere}(test, start);
+  mixin-super-stub method lastIndexOf(covariant-by-class core::Object? element, [core::int? start = #C1]) → core::int
+    return super.{col::ListMixin::lastIndexOf}(element, start);
+  mixin-super-stub method lastIndexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int? start = #C1]) → core::int
+    return super.{col::ListMixin::lastIndexWhere}(test, start);
+  mixin-super-stub method insert(core::int index, covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void
+    return super.{col::ListMixin::insert}(index, element);
+  mixin-super-stub method removeAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::removeAt}(index);
+  mixin-super-stub method insertAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::insertAll}(index, iterable);
+  mixin-super-stub method setAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::setAll}(index, iterable);
+  mixin-super-stub get reversed() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::reversed};
+  mixin-super-stub method toString() → core::String
+    return super.{col::ListMixin::toString}();
+}
+class NegativeLengthList<E extends core::Object? = dynamic> extends self::_NegativeLengthList&Object&ListMixin<self::NegativeLengthList::E%> {
+  final field core::List<self::NegativeLengthList::E%> _list;
+  constructor •(core::List<self::NegativeLengthList::E%> _list) → self::NegativeLengthList<self::NegativeLengthList::E%>
+    : self::NegativeLengthList::_list = _list, super self::_NegativeLengthList&Object&ListMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int};
+  set length(core::int value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length} = value;
+  }
+  operator [](core::int index) → self::NegativeLengthList::E%
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]}(index){(core::int) → self::NegativeLengthList::E%};
+  operator []=(core::int index, covariant-by-class self::NegativeLengthList::E% value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]=}(index, value){(core::int, self::NegativeLengthList::E%) → void};
+  }
+}
+abstract class _NegativeLengthMap&Object&MapMixin<K extends core::Object? = dynamic, V extends core::Object? = dynamic> = core::Object with col::MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthMap&Object&MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>
+    : super core::Object::•()
+    ;
+  abstract mixin-stub operator [](core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?; -> col::MapMixin::[]
+  abstract mixin-stub operator []=(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class self::_NegativeLengthMap&Object&MapMixin::V% value) → void; -> col::MapMixin::[]=
+  abstract mixin-stub method remove(core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?; -> col::MapMixin::remove
+  abstract mixin-stub method clear() → void; -> col::MapMixin::clear
+  mixin-super-stub get length() → core::int
+    return super.{col::MapMixin::length};
+  abstract mixin-stub get keys() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>; -> col::MapMixin::keys
+  mixin-super-stub method cast<RK extends core::Object? = dynamic, RV extends core::Object? = dynamic>() → core::Map<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>
+    return super.{col::MapMixin::cast}<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>();
+  mixin-super-stub method forEach((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void action) → void
+    return super.{col::MapMixin::forEach}(action);
+  mixin-super-stub method addAll(covariant-by-class core::Map<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> other) → void
+    return super.{col::MapMixin::addAll}(other);
+  mixin-super-stub method containsValue(core::Object? value) → core::bool
+    return super.{col::MapMixin::containsValue}(value);
+  mixin-super-stub method putIfAbsent(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class () → self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent) → self::_NegativeLengthMap&Object&MapMixin::V%
+    return super.{col::MapMixin::putIfAbsent}(key, ifAbsent);
+  mixin-super-stub method update(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update, {covariant-by-class () →? self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent = #C1}) → self::_NegativeLengthMap&Object&MapMixin::V%
+    return super.{col::MapMixin::update}(key, update, ifAbsent: ifAbsent);
+  mixin-super-stub method updateAll(covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update) → void
+    return super.{col::MapMixin::updateAll}(update);
+  mixin-super-stub get entries() → core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>
+    return super.{col::MapMixin::entries};
+  mixin-super-stub method map<K2 extends core::Object? = dynamic, V2 extends core::Object? = dynamic>((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> transform) → core::Map<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>
+    return super.{col::MapMixin::map}<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>(transform);
+  mixin-super-stub method addEntries(covariant-by-class core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> newEntries) → void
+    return super.{col::MapMixin::addEntries}(newEntries);
+  mixin-super-stub method removeWhere((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::bool test) → void
+    return super.{col::MapMixin::removeWhere}(test);
+  mixin-super-stub method containsKey(core::Object? key) → core::bool
+    return super.{col::MapMixin::containsKey}(key);
+  mixin-super-stub get isEmpty() → core::bool
+    return super.{col::MapMixin::isEmpty};
+  mixin-super-stub get isNotEmpty() → core::bool
+    return super.{col::MapMixin::isNotEmpty};
+  mixin-super-stub get values() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::V%>
+    return super.{col::MapMixin::values};
+  mixin-super-stub method toString() → core::String
+    return super.{col::MapMixin::toString}();
+}
+class NegativeLengthMap<K extends core::Object? = dynamic, V extends core::Object? = dynamic> extends self::_NegativeLengthMap&Object&MapMixin<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> {
+  final field core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map;
+  constructor •(core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map) → self::NegativeLengthMap<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>
+    : self::NegativeLengthMap::_map = _map, super self::_NegativeLengthMap&Object&MapMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int};
+  operator [](core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  operator []=(covariant-by-class self::NegativeLengthMap::K% key, covariant-by-class self::NegativeLengthMap::V% value) → void {
+    this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]=}(key, value){(self::NegativeLengthMap::K%, self::NegativeLengthMap::V%) → void};
+  }
+  get keys() → core::Iterable<self::NegativeLengthMap::K%>
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::keys}{core::Iterable<self::NegativeLengthMap::K%>};
+  method remove(core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::remove}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  method clear() → void
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::clear}(){() → void};
+}
+static method switchList(core::List<core::int> list) → core::int
+  return block {
+    core::int #t1;
+    final synthesized core::List<core::int> #0#0 = list;
+    late final synthesized core::int #0#1 = #0#0.{core::List::length}{core::int};
+    #L1:
+    {
+      {
+        if(#0#1.{core::num::>=}(#C5){(core::num) → core::bool}) {
+          #t1 = 2;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C6) {
+          #t1 = 1;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C4){(core::num) → core::bool}) {
+          #t1 = 0;
+          break #L1;
+        }
+      }
+      throw new _in::ReachabilityError::•("`null` encountered as case in a switch expression with a non-nullable type.");
+    }
+  } =>#t1;
+static method switchMap(core::Map<core::int, core::String> map) → core::int
+  return block {
+    core::int #t2;
+    final synthesized core::Map<core::int, core::String> #0#0 = map;
+    late final synthesized core::int #0#1 = #0#0.{core::Map::length}{core::int};
+    #L2:
+    {
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C6 && #0#0.{core::Map::containsKey}(#C4){(core::Object?) → core::bool} && (let final dynamic #t3 = #0#0.{core::Map::[]}(#C4){(core::Object?) → core::String?} in true)) {
+          #t2 = 1;
+          break #L2;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C4){(core::num) → core::bool}) {
+          #t2 = 0;
+          break #L2;
+        }
+      }
+      {
+        if(true) {
+          #t2 = 2;
+          break #L2;
+        }
+      }
+      throw new _in::ReachabilityError::•("`null` encountered as case in a switch expression with a non-nullable type.");
+    }
+  } =>#t2;
+static method main() → dynamic {
+  self::expect(0, self::switchList(<core::int>[]));
+  self::expect(1, self::switchList(<core::int>[0]));
+  self::expect(2, self::switchList(<core::int>[0, 1]));
+  self::expect(0, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[])));
+  self::expect(1, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[0])));
+  self::expect(2, self::switchList(new self::NegativeLengthList::•<core::int>(<core::int>[0, 1])));
+  self::expect(0, self::switchMap(<core::int, core::String>{}));
+  self::expect(1, self::switchMap(<core::int, core::String>{0: ""}));
+  self::expect(2, self::switchMap(<core::int, core::String>{1: ""}));
+  self::expect(0, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{})));
+  self::expect(1, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{0: ""})));
+  self::expect(2, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{1: ""})));
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!(expected =={core::Object::==}{(core::Object) → core::bool} actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = null
+  #C2 = ""
+  #C3 = true
+  #C4 = 0
+  #C5 = 2
+  #C6 = 1
+}
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart.weak.outline.expect b/pkg/front_end/testcases/patterns/negative_length.dart.weak.outline.expect
new file mode 100644
index 00000000000..5e3bb73d864
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart.weak.outline.expect
@@ -0,0 +1,215 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+import "dart:math" as math;
+
+import "dart:collection";
+
+abstract class _NegativeLengthList&Object&ListMixin<E extends core::Object? = dynamic> = core::Object with col::ListMixin<self::_NegativeLengthList&Object&ListMixin::E%> /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthList&Object&ListMixin<self::_NegativeLengthList&Object&ListMixin::E%>
+    : super core::Object::•()
+    ;
+  mixin-super-stub get first() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::first};
+  mixin-super-stub set first(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void
+    return super.{col::ListMixin::first} = value;
+  mixin-super-stub get last() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::last};
+  mixin-super-stub set last(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void
+    return super.{col::ListMixin::last} = value;
+  mixin-super-stub get iterator() → core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::iterator};
+  mixin-super-stub method elementAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::elementAt}(index);
+  mixin-super-stub method followedBy(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::followedBy}(other);
+  mixin-super-stub method forEach((self::_NegativeLengthList&Object&ListMixin::E%) → void action) → void
+    return super.{col::ListMixin::forEach}(action);
+  mixin-super-stub get isEmpty() → core::bool
+    return super.{col::ListMixin::isEmpty};
+  mixin-super-stub get isNotEmpty() → core::bool
+    return super.{col::ListMixin::isNotEmpty};
+  mixin-super-stub get single() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::single};
+  mixin-super-stub method contains(core::Object? element) → core::bool
+    return super.{col::ListMixin::contains}(element);
+  mixin-super-stub method every((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool
+    return super.{col::ListMixin::every}(test);
+  mixin-super-stub method any((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool
+    return super.{col::ListMixin::any}(test);
+  mixin-super-stub method firstWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::firstWhere}(test, orElse: orElse);
+  mixin-super-stub method lastWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::lastWhere}(test, orElse: orElse);
+  mixin-super-stub method singleWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse}) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::singleWhere}(test, orElse: orElse);
+  mixin-super-stub method join([core::String separator]) → core::String
+    return super.{col::ListMixin::join}(separator);
+  mixin-super-stub method where((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::where}(test);
+  mixin-super-stub method whereType<T extends core::Object? = dynamic>() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::whereType::T%>
+    return super.{col::ListMixin::whereType}<self::_NegativeLengthList&Object&ListMixin::whereType::T%>();
+  mixin-super-stub method map<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::map::T% f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::map::T%>
+    return super.{col::ListMixin::map}<self::_NegativeLengthList&Object&ListMixin::map::T%>(f);
+  mixin-super-stub method expand<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%> f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%>
+    return super.{col::ListMixin::expand}<self::_NegativeLengthList&Object&ListMixin::expand::T%>(f);
+  mixin-super-stub method reduce(covariant-by-class (self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::E% combine) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::reduce}(combine);
+  mixin-super-stub method fold<T extends core::Object? = dynamic>(self::_NegativeLengthList&Object&ListMixin::fold::T% initialValue, (self::_NegativeLengthList&Object&ListMixin::fold::T%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::fold::T% combine) → self::_NegativeLengthList&Object&ListMixin::fold::T%
+    return super.{col::ListMixin::fold}<self::_NegativeLengthList&Object&ListMixin::fold::T%>(initialValue, combine);
+  mixin-super-stub method skip(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::skip}(count);
+  mixin-super-stub method skipWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::skipWhile}(test);
+  mixin-super-stub method take(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::take}(count);
+  mixin-super-stub method takeWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::takeWhile}(test);
+  mixin-super-stub method toList({core::bool growable}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::toList}(growable: growable);
+  mixin-super-stub method toSet() → core::Set<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::toSet}();
+  mixin-super-stub method add(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void
+    return super.{col::ListMixin::add}(element);
+  mixin-super-stub method addAll(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::addAll}(iterable);
+  mixin-super-stub method remove(core::Object? element) → core::bool
+    return super.{col::ListMixin::remove}(element);
+  mixin-super-stub method _closeGap(core::int start, core::int end) → void
+    return super.{col::ListMixin::_closeGap}(start, end);
+  mixin-super-stub method removeWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void
+    return super.{col::ListMixin::removeWhere}(test);
+  mixin-super-stub method retainWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void
+    return super.{col::ListMixin::retainWhere}(test);
+  mixin-super-stub method _filter((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, core::bool retainMatching) → void
+    return super.{col::ListMixin::_filter}(test, retainMatching);
+  mixin-super-stub method clear() → void
+    return super.{col::ListMixin::clear}();
+  mixin-super-stub method cast<R extends core::Object? = dynamic>() → core::List<self::_NegativeLengthList&Object&ListMixin::cast::R%>
+    return super.{col::ListMixin::cast}<self::_NegativeLengthList&Object&ListMixin::cast::R%>();
+  mixin-super-stub method removeLast() → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::removeLast}();
+  mixin-super-stub method sort([(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) →? core::int compare]) → void
+    return super.{col::ListMixin::sort}(compare);
+  mixin-super-stub method shuffle([math::Random? random]) → void
+    return super.{col::ListMixin::shuffle}(random);
+  mixin-super-stub method asMap() → core::Map<core::int, self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::asMap}();
+  mixin-super-stub operator +(covariant-by-class core::List<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::+}(other);
+  mixin-super-stub method sublist(core::int start, [core::int? end]) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::sublist}(start, end);
+  mixin-super-stub method getRange(core::int start, core::int end) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::getRange}(start, end);
+  mixin-super-stub method removeRange(core::int start, core::int end) → void
+    return super.{col::ListMixin::removeRange}(start, end);
+  mixin-super-stub method fillRange(core::int start, core::int end, [covariant-by-class self::_NegativeLengthList&Object&ListMixin::E? fill]) → void
+    return super.{col::ListMixin::fillRange}(start, end, fill);
+  mixin-super-stub method setRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable, [core::int skipCount]) → void
+    return super.{col::ListMixin::setRange}(start, end, iterable, skipCount);
+  mixin-super-stub method replaceRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> newContents) → void
+    return super.{col::ListMixin::replaceRange}(start, end, newContents);
+  mixin-super-stub method indexOf(covariant-by-class core::Object? element, [core::int start]) → core::int
+    return super.{col::ListMixin::indexOf}(element, start);
+  mixin-super-stub method indexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int start]) → core::int
+    return super.{col::ListMixin::indexWhere}(test, start);
+  mixin-super-stub method lastIndexOf(covariant-by-class core::Object? element, [core::int? start]) → core::int
+    return super.{col::ListMixin::lastIndexOf}(element, start);
+  mixin-super-stub method lastIndexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int? start]) → core::int
+    return super.{col::ListMixin::lastIndexWhere}(test, start);
+  mixin-super-stub method insert(core::int index, covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void
+    return super.{col::ListMixin::insert}(index, element);
+  mixin-super-stub method removeAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return super.{col::ListMixin::removeAt}(index);
+  mixin-super-stub method insertAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::insertAll}(index, iterable);
+  mixin-super-stub method setAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void
+    return super.{col::ListMixin::setAll}(index, iterable);
+  mixin-super-stub get reversed() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return super.{col::ListMixin::reversed};
+  mixin-super-stub method toString() → core::String
+    return super.{col::ListMixin::toString}();
+}
+class NegativeLengthList<E extends core::Object? = dynamic> extends self::_NegativeLengthList&Object&ListMixin<self::NegativeLengthList::E%> {
+  final field core::List<self::NegativeLengthList::E%> _list;
+  constructor •(core::List<self::NegativeLengthList::E%> _list) → self::NegativeLengthList<self::NegativeLengthList::E%>
+    ;
+  get length() → core::int
+    ;
+  set length(core::int value) → void
+    ;
+  operator [](core::int index) → self::NegativeLengthList::E%
+    ;
+  operator []=(core::int index, covariant-by-class self::NegativeLengthList::E% value) → void
+    ;
+}
+abstract class _NegativeLengthMap&Object&MapMixin<K extends core::Object? = dynamic, V extends core::Object? = dynamic> = core::Object with col::MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> /*isAnonymousMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthMap&Object&MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>
+    : super core::Object::•()
+    ;
+  abstract mixin-stub operator [](core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?; -> col::MapMixin::[]
+  abstract mixin-stub operator []=(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class self::_NegativeLengthMap&Object&MapMixin::V% value) → void; -> col::MapMixin::[]=
+  abstract mixin-stub method remove(core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?; -> col::MapMixin::remove
+  abstract mixin-stub method clear() → void; -> col::MapMixin::clear
+  mixin-super-stub get length() → core::int
+    return super.{col::MapMixin::length};
+  abstract mixin-stub get keys() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>; -> col::MapMixin::keys
+  mixin-super-stub method cast<RK extends core::Object? = dynamic, RV extends core::Object? = dynamic>() → core::Map<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>
+    return super.{col::MapMixin::cast}<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>();
+  mixin-super-stub method forEach((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void action) → void
+    return super.{col::MapMixin::forEach}(action);
+  mixin-super-stub method addAll(covariant-by-class core::Map<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> other) → void
+    return super.{col::MapMixin::addAll}(other);
+  mixin-super-stub method containsValue(core::Object? value) → core::bool
+    return super.{col::MapMixin::containsValue}(value);
+  mixin-super-stub method putIfAbsent(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class () → self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent) → self::_NegativeLengthMap&Object&MapMixin::V%
+    return super.{col::MapMixin::putIfAbsent}(key, ifAbsent);
+  mixin-super-stub method update(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update, {covariant-by-class () →? self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent}) → self::_NegativeLengthMap&Object&MapMixin::V%
+    return super.{col::MapMixin::update}(key, update, ifAbsent: ifAbsent);
+  mixin-super-stub method updateAll(covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update) → void
+    return super.{col::MapMixin::updateAll}(update);
+  mixin-super-stub get entries() → core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>
+    return super.{col::MapMixin::entries};
+  mixin-super-stub method map<K2 extends core::Object? = dynamic, V2 extends core::Object? = dynamic>((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> transform) → core::Map<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>
+    return super.{col::MapMixin::map}<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>(transform);
+  mixin-super-stub method addEntries(covariant-by-class core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> newEntries) → void
+    return super.{col::MapMixin::addEntries}(newEntries);
+  mixin-super-stub method removeWhere((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::bool test) → void
+    return super.{col::MapMixin::removeWhere}(test);
+  mixin-super-stub method containsKey(core::Object? key) → core::bool
+    return super.{col::MapMixin::containsKey}(key);
+  mixin-super-stub get isEmpty() → core::bool
+    return super.{col::MapMixin::isEmpty};
+  mixin-super-stub get isNotEmpty() → core::bool
+    return super.{col::MapMixin::isNotEmpty};
+  mixin-super-stub get values() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::V%>
+    return super.{col::MapMixin::values};
+  mixin-super-stub method toString() → core::String
+    return super.{col::MapMixin::toString}();
+}
+class NegativeLengthMap<K extends core::Object? = dynamic, V extends core::Object? = dynamic> extends self::_NegativeLengthMap&Object&MapMixin<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> {
+  final field core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map;
+  constructor •(core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map) → self::NegativeLengthMap<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>
+    ;
+  get length() → core::int
+    ;
+  operator [](core::Object? key) → self::NegativeLengthMap::V?
+    ;
+  operator []=(covariant-by-class self::NegativeLengthMap::K% key, covariant-by-class self::NegativeLengthMap::V% value) → void
+    ;
+  get keys() → core::Iterable<self::NegativeLengthMap::K%>
+    ;
+  method remove(core::Object? key) → self::NegativeLengthMap::V?
+    ;
+  method clear() → void
+    ;
+}
+static method switchList(core::List<core::int> list) → core::int
+  ;
+static method switchMap(core::Map<core::int, core::String> map) → core::int
+  ;
+static method main() → dynamic
+  ;
+static method expect(dynamic expected, dynamic actual) → dynamic
+  ;
diff --git a/pkg/front_end/testcases/patterns/negative_length.dart.weak.transformed.expect b/pkg/front_end/testcases/patterns/negative_length.dart.weak.transformed.expect
new file mode 100644
index 00000000000..4253371688d
--- /dev/null
+++ b/pkg/front_end/testcases/patterns/negative_length.dart.weak.transformed.expect
@@ -0,0 +1,783 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "dart:collection" as col;
+import "dart:_internal" as _in;
+import "dart:math" as math;
+
+import "dart:collection";
+
+abstract class _NegativeLengthList&Object&ListMixin<E extends core::Object? = dynamic> extends core::Object implements col::ListMixin<self::_NegativeLengthList&Object&ListMixin::E%> /*isAnonymousMixin,isEliminatedMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthList&Object&ListMixin<self::_NegativeLengthList&Object&ListMixin::E%>
+    : super core::Object::•()
+    ;
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ first() → self::_NegativeLengthList&Object&ListMixin::E% {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    return this.{core::List::[]}(0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+  }
+  set /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ first(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    this.{core::List::[]=}(0, value){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+  }
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ last() → self::_NegativeLengthList&Object&ListMixin::E% {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    return this.{core::List::[]}(this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int}){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+  }
+  set /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ last(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% value) → void {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    this.{core::List::[]=}(this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int}, value){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+  }
+  @#C3
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ iterator() → core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::ListIterator::•<self::_NegativeLengthList&Object&ListMixin::E%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ elementAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E%
+    return this.{core::List::[]}(index){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ followedBy(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return _in::FollowedByIterable::firstEfficient<self::_NegativeLengthList&Object&ListMixin::E%>(this, other);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ forEach((self::_NegativeLengthList&Object&ListMixin::E%) → void action) → void {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      action(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+  }
+  @#C3
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ isEmpty() → core::bool
+    return this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0;
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ isNotEmpty() → core::bool
+    return !this.{col::ListMixin::isEmpty}{core::bool};
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ single() → self::_NegativeLengthList&Object&ListMixin::E% {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    if(this.{core::List::length}{core::int}.{core::num::>}(1){(core::num) → core::bool})
+      throw _in::IterableElementError::tooMany();
+    return this.{core::List::[]}(0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ contains(core::Object? element) → core::bool {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%} =={core::Object::==}{(core::Object) → core::bool} element)
+        return true;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return false;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ every((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(!test(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return false;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return true;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ any((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::bool {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(test(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return true;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return false;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ firstWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C2}) → self::_NegativeLengthList&Object&ListMixin::E% {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      self::_NegativeLengthList&Object&ListMixin::E% element = this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(test(element){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return element;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    if(!(orElse == null))
+      return orElse{() → self::_NegativeLengthList&Object&ListMixin::E%}(){() → self::_NegativeLengthList&Object&ListMixin::E%};
+    throw _in::IterableElementError::noElement();
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ lastWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C2}) → self::_NegativeLengthList&Object&ListMixin::E% {
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = length.{core::num::-}(1){(core::num) → core::int}; i.{core::num::>=}(0){(core::num) → core::bool}; i = i.{core::num::-}(1){(core::num) → core::int}) {
+      self::_NegativeLengthList&Object&ListMixin::E% element = this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(test(element){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return element;
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    if(!(orElse == null))
+      return orElse{() → self::_NegativeLengthList&Object&ListMixin::E%}(){() → self::_NegativeLengthList&Object&ListMixin::E%};
+    throw _in::IterableElementError::noElement();
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ singleWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, {covariant-by-class () →? self::_NegativeLengthList&Object&ListMixin::E% orElse = #C2}) → self::_NegativeLengthList&Object&ListMixin::E% {
+    core::int length = this.{core::List::length}{core::int};
+    late self::_NegativeLengthList&Object&ListMixin::E% match;
+    core::bool matchFound = false;
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      self::_NegativeLengthList&Object&ListMixin::E% element = this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(test(element){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool}) {
+        if(matchFound) {
+          throw _in::IterableElementError::tooMany();
+        }
+        matchFound = true;
+        match = element;
+      }
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    if(matchFound)
+      return match;
+    if(!(orElse == null))
+      return orElse{() → self::_NegativeLengthList&Object&ListMixin::E%}(){() → self::_NegativeLengthList&Object&ListMixin::E%};
+    throw _in::IterableElementError::noElement();
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ join([core::String separator = #C4]) → core::String {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0)
+      return "";
+    core::StringBuffer buffer = let final core::StringBuffer #t1 = new core::StringBuffer::•() in block {
+      #t1.{core::StringBuffer::writeAll}(this, separator){(core::Iterable<dynamic>, [core::String]) → void};
+    } =>#t1;
+    return buffer.{core::StringBuffer::toString}(){() → core::String};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ where((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::WhereIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, test);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ whereType<T extends core::Object? = dynamic>() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::whereType::T%>
+    return new _in::WhereTypeIterable::•<self::_NegativeLengthList&Object&ListMixin::whereType::T%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ map<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::map::T% f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::map::T%>
+    return new _in::MappedListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::map::T%>(this, f);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ expand<T extends core::Object? = dynamic>((self::_NegativeLengthList&Object&ListMixin::E%) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%> f) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::expand::T%>
+    return new _in::ExpandIterable::•<self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::expand::T%>(this, f);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ reduce(covariant-by-class (self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::E% combine) → self::_NegativeLengthList&Object&ListMixin::E% {
+    core::int length = this.{core::List::length}{core::int};
+    if(length =={core::num::==}{(core::Object) → core::bool} 0)
+      throw _in::IterableElementError::noElement();
+    self::_NegativeLengthList&Object&ListMixin::E% value = this.{core::List::[]}(0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+    for (core::int i = 1; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      value = combine(value, this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return value;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ fold<T extends core::Object? = dynamic>(self::_NegativeLengthList&Object&ListMixin::fold::T% initialValue, (self::_NegativeLengthList&Object&ListMixin::fold::T%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::fold::T% combine) → self::_NegativeLengthList&Object&ListMixin::fold::T% {
+    self::_NegativeLengthList&Object&ListMixin::fold::T% value = initialValue;
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      value = combine(value, this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::fold::T%, self::_NegativeLengthList&Object&ListMixin::E%) → self::_NegativeLengthList&Object&ListMixin::fold::T%};
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    return value;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ skip(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::SubListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, count, null);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ skipWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> {
+    return new _in::SkipWhileIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, test);
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ take(core::int count) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::SubListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, 0, _in::checkNotNullable<core::int>(count, "count"));
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ takeWhile((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> {
+    return new _in::TakeWhileIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, test);
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ toList({core::bool growable = #C5}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%> {
+    if(this.{col::ListMixin::isEmpty}{core::bool})
+      return core::List::empty<self::_NegativeLengthList&Object&ListMixin::E%>(growable: growable);
+    self::_NegativeLengthList&Object&ListMixin::E% first = this.{core::List::[]}(0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+    core::List<self::_NegativeLengthList&Object&ListMixin::E%> result = core::List::filled<self::_NegativeLengthList&Object&ListMixin::E%>(this.{core::List::length}{core::int}, first, growable: growable);
+    for (core::int i = 1; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      result.{core::List::[]=}(i, this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ toSet() → core::Set<self::_NegativeLengthList&Object&ListMixin::E%> {
+    core::Set<self::_NegativeLengthList&Object&ListMixin::E%> result = new col::_Set::•<self::_NegativeLengthList&Object&ListMixin::E%>();
+    for (core::int i = 0; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      result.{core::Set::add}(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool};
+    }
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ add(covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void {
+    this.{core::List::[]=}(let final core::int #t2 = this.{core::List::length}{core::int} in let final core::int #t3 = this.{core::List::length} = #t2.{core::num::+}(1){(core::num) → core::int} in #t2, element){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ addAll(covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void {
+    core::int i = this.{core::List::length}{core::int};
+    {
+      synthesized core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%> :sync-for-iterator = iterable.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthList&Object&ListMixin::E% element = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthList&Object&ListMixin::E%};
+        {
+          assert(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} i || (throw new core::ConcurrentModificationError::•(this)));
+          this.{col::ListMixin::add}(element){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+          i = i.{core::num::+}(1){(core::num) → core::int};
+        }
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ remove(core::Object? element) → core::bool {
+    for (core::int i = 0; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%} =={core::Object::==}{(core::Object) → core::bool} element) {
+        this.{col::ListMixin::_closeGap}(i, i.{core::num::+}(1){(core::num) → core::int}){(core::int, core::int) → void};
+        return true;
+      }
+    }
+    return false;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ _closeGap(core::int start, core::int end) → void {
+    core::int length = this.{core::List::length}{core::int};
+    assert(0.{core::num::<=}(start){(core::num) → core::bool});
+    assert(start.{core::num::<}(end){(core::num) → core::bool});
+    assert(end.{core::num::<=}(length){(core::num) → core::bool});
+    core::int size = end.{core::num::-}(start){(core::num) → core::int};
+    for (core::int i = end; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      this.{core::List::[]=}(i.{core::num::-}(size){(core::num) → core::int}, this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+    this.{core::List::length} = length.{core::num::-}(size){(core::num) → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ removeWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void {
+    this.{col::ListMixin::_filter}(test, false){((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool, core::bool) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ retainWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test) → void {
+    this.{col::ListMixin::_filter}(test, true){((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool, core::bool) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ _filter((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, core::bool retainMatching) → void {
+    core::List<self::_NegativeLengthList&Object&ListMixin::E%> retained = core::_GrowableList::•<self::_NegativeLengthList&Object&ListMixin::E%>(0);
+    core::int length = this.{core::List::length}{core::int};
+    for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      self::_NegativeLengthList&Object&ListMixin::E% element = this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      if(test(element){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool} =={core::Object::==}{(core::Object) → core::bool} retainMatching) {
+        retained.{core::List::add}(element){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      }
+      if(!(length =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+        throw new core::ConcurrentModificationError::•(this);
+      }
+    }
+    if(!(retained.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int})) {
+      this.{col::ListMixin::setRange}(0, retained.{core::List::length}{core::int}, retained){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+      this.{core::List::length} = retained.{core::List::length}{core::int};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ clear() → void {
+    this.{core::List::length} = 0;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ cast<R extends core::Object? = dynamic>() → core::List<self::_NegativeLengthList&Object&ListMixin::cast::R%>
+    return core::List::castFrom<self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::cast::R%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ removeLast() → self::_NegativeLengthList&Object&ListMixin::E% {
+    if(this.{core::List::length}{core::int} =={core::num::==}{(core::Object) → core::bool} 0) {
+      throw _in::IterableElementError::noElement();
+    }
+    self::_NegativeLengthList&Object&ListMixin::E% result = this.{core::List::[]}(this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int}){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+    this.{core::List::length} = this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int};
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ sort([(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) →? core::int compare = #C2]) → void {
+    _in::Sort::sort<self::_NegativeLengthList&Object&ListMixin::E%>(this, let final (self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) →? core::int #t4 = compare in #t4 == null ?{(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → core::int} #C6 : #t4{(self::_NegativeLengthList&Object&ListMixin::E%, self::_NegativeLengthList&Object&ListMixin::E%) → core::int});
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ shuffle([math::Random? random = #C2]) → void {
+    random == null ?{math::Random} random = math::Random::•() : null;
+    if(random{math::Random} == null)
+      throw "!";
+    core::int length = this.{core::List::length}{core::int};
+    while (length.{core::num::>}(1){(core::num) → core::bool}) {
+      core::int pos = random{math::Random}.{math::Random::nextInt}(length){(core::int) → core::int};
+      length = length.{core::num::-}(1){(core::num) → core::int};
+      self::_NegativeLengthList&Object&ListMixin::E% tmp = this.{core::List::[]}(length){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+      this.{core::List::[]=}(length, this.{core::List::[]}(pos){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      this.{core::List::[]=}(pos, tmp){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ asMap() → core::Map<core::int, self::_NegativeLengthList&Object&ListMixin::E%> {
+    return new _in::ListMapView::•<self::_NegativeLengthList&Object&ListMixin::E%>(this);
+  }
+  operator /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ +(covariant-by-class core::List<self::_NegativeLengthList&Object&ListMixin::E%> other) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>
+    return block {
+      final core::List<self::_NegativeLengthList&Object&ListMixin::E%> #t5 = core::List::of<self::_NegativeLengthList&Object&ListMixin::E%>(this);
+      #t5.{core::List::addAll}{Invariant}(other){(core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>) → void};
+    } =>#t5;
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ sublist(core::int start, [core::int? end = #C2]) → core::List<self::_NegativeLengthList&Object&ListMixin::E%> {
+    core::int listLength = this.{core::List::length}{core::int};
+    end == null ?{core::int} end = listLength : null;
+    if(end{core::int} == null)
+      throw "!";
+    core::RangeError::checkValidRange(start, end{core::int}, listLength);
+    return core::List::from<self::_NegativeLengthList&Object&ListMixin::E%>(this.{col::ListMixin::getRange}(start, end{core::int}){(core::int, core::int) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>});
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ getRange(core::int start, core::int end) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> {
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    return new _in::SubListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this, start, end);
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ removeRange(core::int start, core::int end) → void {
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    if(end.{core::num::>}(start){(core::num) → core::bool}) {
+      this.{col::ListMixin::_closeGap}(start, end){(core::int, core::int) → void};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ fillRange(core::int start, core::int end, [covariant-by-class self::_NegativeLengthList&Object&ListMixin::E? fill = #C2]) → void {
+    self::_NegativeLengthList&Object&ListMixin::E% value = let self::_NegativeLengthList&Object&ListMixin::E? #t6 = fill in #t6 == null ?{self::_NegativeLengthList&Object&ListMixin::E%} #t6 : #t6{self::_NegativeLengthList&Object&ListMixin::E%};
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    for (core::int i = start; i.{core::num::<}(end){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      this.{core::List::[]=}(i, value){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ setRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable, [core::int skipCount = #C7]) → void {
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    core::int length = end.{core::num::-}(start){(core::num) → core::int};
+    if(length =={core::num::==}{(core::Object) → core::bool} 0)
+      return;
+    core::RangeError::checkNotNegative(skipCount, "skipCount");
+    core::List<self::_NegativeLengthList&Object&ListMixin::E%> otherList;
+    core::int otherStart;
+    if(iterable is{ForNonNullableByDefault} core::List<self::_NegativeLengthList&Object&ListMixin::E%>) {
+      otherList = iterable{core::List<self::_NegativeLengthList&Object&ListMixin::E%>};
+      otherStart = skipCount;
+    }
+    else {
+      otherList = iterable.{core::Iterable::skip}(skipCount){(core::int) → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>}.{core::Iterable::toList}(growable: false){({growable: core::bool}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>};
+      otherStart = 0;
+    }
+    if(otherStart.{core::num::+}(length){(core::num) → core::int}.{core::num::>}(otherList.{core::List::length}{core::int}){(core::num) → core::bool}) {
+      throw _in::IterableElementError::tooFew();
+    }
+    if(otherStart.{core::num::<}(start){(core::num) → core::bool}) {
+      for (core::int i = length.{core::num::-}(1){(core::num) → core::int}; i.{core::num::>=}(0){(core::num) → core::bool}; i = i.{core::num::-}(1){(core::num) → core::int}) {
+        this.{core::List::[]=}(start.{core::num::+}(i){(core::num) → core::int}, otherList.{core::List::[]}(otherStart.{core::num::+}(i){(core::num) → core::int}){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      }
+    }
+    else {
+      for (core::int i = 0; i.{core::num::<}(length){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+        this.{core::List::[]=}(start.{core::num::+}(i){(core::num) → core::int}, otherList.{core::List::[]}(otherStart.{core::num::+}(i){(core::num) → core::int}){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ replaceRange(core::int start, core::int end, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> newContents) → void {
+    core::RangeError::checkValidRange(start, end, this.{core::List::length}{core::int});
+    if(start =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int}) {
+      this.{col::ListMixin::addAll}(newContents){(core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>) → void};
+      return;
+    }
+    if(!(newContents is{ForNonNullableByDefault} _in::EfficientLengthIterable<dynamic>)) {
+      newContents = newContents.{core::Iterable::toList}(){({growable: core::bool}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>};
+    }
+    core::int removeLength = end.{core::num::-}(start){(core::num) → core::int};
+    core::int insertLength = newContents.{core::Iterable::length}{core::int};
+    if(removeLength.{core::num::>=}(insertLength){(core::num) → core::bool}) {
+      core::int insertEnd = start.{core::num::+}(insertLength){(core::num) → core::int};
+      this.{col::ListMixin::setRange}(start, insertEnd, newContents){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+      if(removeLength.{core::num::>}(insertLength){(core::num) → core::bool}) {
+        this.{col::ListMixin::_closeGap}(insertEnd, end){(core::int, core::int) → void};
+      }
+    }
+    else
+      if(end =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int}) {
+        core::int i = start;
+        {
+          synthesized core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%> :sync-for-iterator = newContents.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>};
+          for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+            self::_NegativeLengthList&Object&ListMixin::E% element = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthList&Object&ListMixin::E%};
+            {
+              if(i.{core::num::<}(end){(core::num) → core::bool}) {
+                this.{core::List::[]=}(i, element){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+              }
+              else {
+                this.{col::ListMixin::add}(element){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+              }
+              i = i.{core::num::+}(1){(core::num) → core::int};
+            }
+          }
+        }
+      }
+      else {
+        core::int delta = insertLength.{core::num::-}(removeLength){(core::num) → core::int};
+        core::int oldLength = this.{core::List::length}{core::int};
+        core::int insertEnd = start.{core::num::+}(insertLength){(core::num) → core::int};
+        for (core::int i = oldLength.{core::num::-}(delta){(core::num) → core::int}; i.{core::num::<}(oldLength){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+          this.{col::ListMixin::add}(this.{core::List::[]}(i.{core::num::>}(0){(core::num) → core::bool} ?{core::int} i : 0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+        }
+        if(insertEnd.{core::num::<}(oldLength){(core::num) → core::bool}) {
+          this.{col::ListMixin::setRange}(insertEnd, oldLength, this, end){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+        }
+        this.{col::ListMixin::setRange}(start, insertEnd, newContents){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+      }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ indexOf(covariant-by-class core::Object? element, [core::int start = #C7]) → core::int {
+    if(start.{core::num::<}(0){(core::num) → core::bool})
+      start = 0;
+    for (core::int i = start; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%} =={core::Object::==}{(core::Object) → core::bool} element)
+        return i;
+    }
+    return 1.{core::int::unary-}(){() → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ indexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int start = #C7]) → core::int {
+    if(start.{core::num::<}(0){(core::num) → core::bool})
+      start = 0;
+    for (core::int i = start; i.{core::num::<}(this.{core::List::length}{core::int}){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      if(test(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return i;
+    }
+    return 1.{core::int::unary-}(){() → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ lastIndexOf(covariant-by-class core::Object? element, [core::int? start = #C2]) → core::int {
+    if(start == null || start{core::int}.{core::num::>=}(this.{core::List::length}{core::int}){(core::num) → core::bool})
+      start = this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int};
+    if(start{core::int} == null)
+      throw "!";
+    for (core::int i = start{core::int}; i.{core::num::>=}(0){(core::num) → core::bool}; i = i.{core::num::-}(1){(core::num) → core::int}) {
+      if(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%} =={core::Object::==}{(core::Object) → core::bool} element)
+        return i;
+    }
+    return 1.{core::int::unary-}(){() → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ lastIndexWhere((self::_NegativeLengthList&Object&ListMixin::E%) → core::bool test, [core::int? start = #C2]) → core::int {
+    if(start == null || start{core::int}.{core::num::>=}(this.{core::List::length}{core::int}){(core::num) → core::bool})
+      start = this.{core::List::length}{core::int}.{core::num::-}(1){(core::num) → core::int};
+    if(start{core::int} == null)
+      throw "!";
+    for (core::int i = start{core::int}; i.{core::num::>=}(0){(core::num) → core::bool}; i = i.{core::num::-}(1){(core::num) → core::int}) {
+      if(test(this.{core::List::[]}(i){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → core::bool})
+        return i;
+    }
+    return 1.{core::int::unary-}(){() → core::int};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ insert(core::int index, covariant-by-class self::_NegativeLengthList&Object&ListMixin::E% element) → void {
+    _in::checkNotNullable<core::int>(index, "index");
+    core::int length = this.{core::List::length}{core::int};
+    core::RangeError::checkValueInInterval(index, 0, length, "index");
+    this.{col::ListMixin::add}(element){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    if(!(index =={core::num::==}{(core::Object) → core::bool} length)) {
+      this.{col::ListMixin::setRange}(index.{core::num::+}(1){(core::num) → core::int}, length.{core::num::+}(1){(core::num) → core::int}, this, index){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+      this.{core::List::[]=}(index, element){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ removeAt(core::int index) → self::_NegativeLengthList&Object&ListMixin::E% {
+    self::_NegativeLengthList&Object&ListMixin::E% result = this.{core::List::[]}(index){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%};
+    this.{col::ListMixin::_closeGap}(index, index.{core::num::+}(1){(core::num) → core::int}){(core::int, core::int) → void};
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ insertAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void {
+    core::RangeError::checkValueInInterval(index, 0, this.{core::List::length}{core::int}, "index");
+    if(index =={core::num::==}{(core::Object) → core::bool} this.{core::List::length}{core::int}) {
+      this.{col::ListMixin::addAll}(iterable){(core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>) → void};
+      return;
+    }
+    if(!(iterable is{ForNonNullableByDefault} _in::EfficientLengthIterable<dynamic>) || core::identical(iterable, this)) {
+      iterable = iterable.{core::Iterable::toList}(){({growable: core::bool}) → core::List<self::_NegativeLengthList&Object&ListMixin::E%>};
+    }
+    core::int insertionLength = iterable.{core::Iterable::length}{core::int};
+    if(insertionLength =={core::num::==}{(core::Object) → core::bool} 0) {
+      return;
+    }
+    core::int oldLength = this.{core::List::length}{core::int};
+    for (core::int i = oldLength.{core::num::-}(insertionLength){(core::num) → core::int}; i.{core::num::<}(oldLength){(core::num) → core::bool}; i = i.{core::num::+}(1){(core::num) → core::int}) {
+      this.{col::ListMixin::add}(this.{core::List::[]}(i.{core::num::>}(0){(core::num) → core::bool} ?{core::int} i : 0){(core::int) → self::_NegativeLengthList&Object&ListMixin::E%}){(self::_NegativeLengthList&Object&ListMixin::E%) → void};
+    }
+    if(!(iterable.{core::Iterable::length}{core::int} =={core::num::==}{(core::Object) → core::bool} insertionLength)) {
+      this.{core::List::length} = this.{core::List::length}{core::int}.{core::num::-}(insertionLength){(core::num) → core::int};
+      throw new core::ConcurrentModificationError::•(iterable);
+    }
+    core::int oldCopyStart = index.{core::num::+}(insertionLength){(core::num) → core::int};
+    if(oldCopyStart.{core::num::<}(oldLength){(core::num) → core::bool}) {
+      this.{col::ListMixin::setRange}(oldCopyStart, oldLength, this, index){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+    }
+    this.{col::ListMixin::setAll}(index, iterable){(core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ setAll(core::int index, covariant-by-class core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%> iterable) → void {
+    if(iterable is{ForNonNullableByDefault} core::List<dynamic>) {
+      this.{col::ListMixin::setRange}(index, index.{core::num::+}(iterable.{core::Iterable::length}{core::int}){(core::num) → core::int}, iterable){(core::int, core::int, core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>, [core::int]) → void};
+    }
+    else {
+      {
+        synthesized core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%> :sync-for-iterator = iterable.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthList&Object&ListMixin::E%>};
+        for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+          self::_NegativeLengthList&Object&ListMixin::E% element = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthList&Object&ListMixin::E%};
+          {
+            this.{core::List::[]=}(let final core::int #t7 = index in let final core::int #t8 = index = #t7.{core::num::+}(1){(core::num) → core::int} in #t7, element){(core::int, self::_NegativeLengthList&Object&ListMixin::E%) → void};
+          }
+        }
+      }
+    }
+  }
+  get /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ reversed() → core::Iterable<self::_NegativeLengthList&Object&ListMixin::E%>
+    return new _in::ReversedListIterable::•<self::_NegativeLengthList&Object&ListMixin::E%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ toString() → core::String
+    return col::IterableBase::iterableToFullString(this, "[", "]");
+  static method /* from org-dartlang-sdk:///sdk/lib/collection/list.dart */ _compareAny(dynamic a, dynamic b) → core::int {
+    return core::Comparable::compare(a as{ForNonNullableByDefault} core::Comparable<dynamic>, b as{ForNonNullableByDefault} core::Comparable<dynamic>);
+  }
+}
+class NegativeLengthList<E extends core::Object? = dynamic> extends self::_NegativeLengthList&Object&ListMixin<self::NegativeLengthList::E%> {
+  final field core::List<self::NegativeLengthList::E%> _list;
+  constructor •(core::List<self::NegativeLengthList::E%> _list) → self::NegativeLengthList<self::NegativeLengthList::E%>
+    : self::NegativeLengthList::_list = _list, super self::_NegativeLengthList&Object&ListMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length}{core::int};
+  set length(core::int value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::length} = value;
+  }
+  operator [](core::int index) → self::NegativeLengthList::E%
+    return this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]}(index){(core::int) → self::NegativeLengthList::E%};
+  operator []=(core::int index, covariant-by-class self::NegativeLengthList::E% value) → void {
+    this.{self::NegativeLengthList::_list}{core::List<self::NegativeLengthList::E%>}.{core::List::[]=}(index, value){(core::int, self::NegativeLengthList::E%) → void};
+  }
+}
+abstract class _NegativeLengthMap&Object&MapMixin<K extends core::Object? = dynamic, V extends core::Object? = dynamic> extends core::Object implements col::MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> /*isAnonymousMixin,isEliminatedMixin,hasConstConstructor*/  {
+  const synthetic constructor •() → self::_NegativeLengthMap&Object&MapMixin<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>
+    : super core::Object::•()
+    ;
+  abstract operator /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ [](core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?;
+  abstract operator /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ []=(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class self::_NegativeLengthMap&Object&MapMixin::V% value) → void;
+  abstract method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ remove(core::Object? key) → self::_NegativeLengthMap&Object&MapMixin::V?;
+  abstract method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ clear() → void;
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ length() → core::int
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::length}{core::int};
+  abstract get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ keys() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>;
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ cast<RK extends core::Object? = dynamic, RV extends core::Object? = dynamic>() → core::Map<self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>
+    return core::Map::castFrom<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%, self::_NegativeLengthMap&Object&MapMixin::cast::RK%, self::_NegativeLengthMap&Object&MapMixin::cast::RV%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ forEach((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void action) → void {
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          action(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t9 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t9 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t9 : #t9{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void};
+        }
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ addAll(covariant-by-class core::Map<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> other) → void {
+    other.{core::Map::forEach}((self::_NegativeLengthMap&Object&MapMixin::K% key, self::_NegativeLengthMap&Object&MapMixin::V% value) → void {
+      this.{col::MapMixin::[]=}(key, value){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void};
+    }){((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void) → void};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ containsValue(core::Object? value) → core::bool {
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          if(this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} =={core::Object::==}{(core::Object) → core::bool} value)
+            return true;
+        }
+      }
+    }
+    return false;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ putIfAbsent(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class () → self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent) → self::_NegativeLengthMap&Object&MapMixin::V% {
+    if(this.{col::MapMixin::containsKey}(key){(core::Object?) → core::bool}) {
+      return let self::_NegativeLengthMap&Object&MapMixin::V? #t10 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t10 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t10 : #t10{self::_NegativeLengthMap&Object&MapMixin::V%};
+    }
+    return let final self::_NegativeLengthMap&Object&MapMixin::K% #t11 = key in let final self::_NegativeLengthMap&Object&MapMixin::V% #t12 = ifAbsent(){() → self::_NegativeLengthMap&Object&MapMixin::V%} in let final void #t13 = this.{col::MapMixin::[]=}(#t11, #t12){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void} in #t12;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ update(covariant-by-class self::_NegativeLengthMap&Object&MapMixin::K% key, covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update, {covariant-by-class () →? self::_NegativeLengthMap&Object&MapMixin::V% ifAbsent = #C2}) → self::_NegativeLengthMap&Object&MapMixin::V% {
+    if(this.{col::MapMixin::containsKey}(key){(core::Object?) → core::bool}) {
+      return let final self::_NegativeLengthMap&Object&MapMixin::K% #t14 = key in let final self::_NegativeLengthMap&Object&MapMixin::V% #t15 = update(let self::_NegativeLengthMap&Object&MapMixin::V? #t16 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t16 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t16 : #t16{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V%} in let final void #t17 = this.{col::MapMixin::[]=}(#t14, #t15){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void} in #t15;
+    }
+    if(!(ifAbsent == null)) {
+      return let final self::_NegativeLengthMap&Object&MapMixin::K% #t18 = key in let final self::_NegativeLengthMap&Object&MapMixin::V% #t19 = ifAbsent{() → self::_NegativeLengthMap&Object&MapMixin::V%}(){() → self::_NegativeLengthMap&Object&MapMixin::V%} in let final void #t20 = this.{col::MapMixin::[]=}(#t18, #t19){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void} in #t19;
+    }
+    throw new core::ArgumentError::value(key, "key", "Key not in map.");
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ updateAll(covariant-by-class (self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V% update) → void {
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          this.{col::MapMixin::[]=}(key, update(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t21 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t21 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t21 : #t21{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void};
+        }
+      }
+    }
+  }
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ entries() → core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> {
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::map}<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>((self::_NegativeLengthMap&Object&MapMixin::K% key) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> => new core::MapEntry::_<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t22 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t22 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t22 : #t22{self::_NegativeLengthMap&Object&MapMixin::V%})){((self::_NegativeLengthMap&Object&MapMixin::K%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>) → core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>};
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ map<K2 extends core::Object? = dynamic, V2 extends core::Object? = dynamic>((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> transform) → core::Map<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> {
+    core::Map<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> result = <self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>{};
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%> entry = transform(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t23 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t23 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t23 : #t23{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%>};
+          result.{core::Map::[]=}(entry.{core::MapEntry::key}{self::_NegativeLengthMap&Object&MapMixin::map::K2%}, entry.{core::MapEntry::value}{self::_NegativeLengthMap&Object&MapMixin::map::V2%}){(self::_NegativeLengthMap&Object&MapMixin::map::K2%, self::_NegativeLengthMap&Object&MapMixin::map::V2%) → void};
+        }
+      }
+    }
+    return result;
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ addEntries(covariant-by-class core::Iterable<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> newEntries) → void {
+    {
+      synthesized core::Iterator<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>> :sync-for-iterator = newEntries.{core::Iterable::iterator}{core::Iterator<core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%> entry = :sync-for-iterator.{core::Iterator::current}{core::MapEntry<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>};
+        {
+          this.{col::MapMixin::[]=}(entry.{core::MapEntry::key}{self::_NegativeLengthMap&Object&MapMixin::K%}, entry.{core::MapEntry::value}{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → void};
+        }
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ removeWhere((self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::bool test) → void {
+    core::List<self::_NegativeLengthMap&Object&MapMixin::K%> keysToRemove = core::_GrowableList::•<self::_NegativeLengthMap&Object&MapMixin::K%>(0);
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          if(test(key, let self::_NegativeLengthMap&Object&MapMixin::V? #t24 = this.{col::MapMixin::[]}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?} in #t24 == null ?{self::_NegativeLengthMap&Object&MapMixin::V%} #t24 : #t24{self::_NegativeLengthMap&Object&MapMixin::V%}){(self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%) → core::bool})
+            keysToRemove.{core::List::add}(key){(self::_NegativeLengthMap&Object&MapMixin::K%) → void};
+        }
+      }
+    }
+    {
+      synthesized core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%> :sync-for-iterator = keysToRemove.{core::Iterable::iterator}{core::Iterator<self::_NegativeLengthMap&Object&MapMixin::K%>};
+      for (; :sync-for-iterator.{core::Iterator::moveNext}(){() → core::bool}; ) {
+        self::_NegativeLengthMap&Object&MapMixin::K% key = :sync-for-iterator.{core::Iterator::current}{self::_NegativeLengthMap&Object&MapMixin::K%};
+        {
+          this.{col::MapMixin::remove}(key){(core::Object?) → self::_NegativeLengthMap&Object&MapMixin::V?};
+        }
+      }
+    }
+  }
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ containsKey(core::Object? key) → core::bool
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::contains}(key){(core::Object?) → core::bool};
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ isEmpty() → core::bool
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::isEmpty}{core::bool};
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ isNotEmpty() → core::bool
+    return this.{col::MapMixin::keys}{core::Iterable<self::_NegativeLengthMap&Object&MapMixin::K%>}.{core::Iterable::isNotEmpty}{core::bool};
+  get /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ values() → core::Iterable<self::_NegativeLengthMap&Object&MapMixin::V%>
+    return new col::_MapBaseValueIterable::•<self::_NegativeLengthMap&Object&MapMixin::K%, self::_NegativeLengthMap&Object&MapMixin::V%>(this);
+  method /* from org-dartlang-sdk:///sdk/lib/collection/maps.dart */ toString() → core::String
+    return col::MapBase::mapToString(this);
+}
+class NegativeLengthMap<K extends core::Object? = dynamic, V extends core::Object? = dynamic> extends self::_NegativeLengthMap&Object&MapMixin<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> {
+  final field core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map;
+  constructor •(core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%> _map) → self::NegativeLengthMap<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>
+    : self::NegativeLengthMap::_map = _map, super self::_NegativeLengthMap&Object&MapMixin::•()
+    ;
+  get length() → core::int
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int}.{core::num::<=}(0){(core::num) → core::bool} ?{core::int} 1.{core::int::unary-}(){() → core::int} : this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::length}{core::int};
+  operator [](core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  operator []=(covariant-by-class self::NegativeLengthMap::K% key, covariant-by-class self::NegativeLengthMap::V% value) → void {
+    this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::[]=}(key, value){(self::NegativeLengthMap::K%, self::NegativeLengthMap::V%) → void};
+  }
+  get keys() → core::Iterable<self::NegativeLengthMap::K%>
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::keys}{core::Iterable<self::NegativeLengthMap::K%>};
+  method remove(core::Object? key) → self::NegativeLengthMap::V?
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::remove}(key){(core::Object?) → self::NegativeLengthMap::V?};
+  method clear() → void
+    return this.{self::NegativeLengthMap::_map}{core::Map<self::NegativeLengthMap::K%, self::NegativeLengthMap::V%>}.{core::Map::clear}(){() → void};
+}
+static method switchList(core::List<core::int> list) → core::int
+  return block {
+    core::int #t25;
+    final synthesized core::List<core::int> #0#0 = list;
+    function ##0#1#initializer() → core::int
+      return #0#0.{core::List::length}{core::int};
+    late final synthesized core::int #0#1 = ##0#1#initializer(){() → core::int};
+    #L1:
+    {
+      {
+        if(#0#1.{core::num::>=}(#C8){(core::num) → core::bool}) {
+          #t25 = 2;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C9) {
+          #t25 = 1;
+          break #L1;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C7){(core::num) → core::bool}) {
+          #t25 = 0;
+          break #L1;
+        }
+      }
+      throw new _in::ReachabilityError::•("`null` encountered as case in a switch expression with a non-nullable type.");
+    }
+  } =>#t25;
+static method switchMap(core::Map<core::int, core::String> map) → core::int
+  return block {
+    core::int #t26;
+    final synthesized core::Map<core::int, core::String> #0#0 = map;
+    function ##0#1#initializer() → core::int
+      return #0#0.{core::Map::length}{core::int};
+    late final synthesized core::int #0#1 = ##0#1#initializer(){() → core::int};
+    #L2:
+    {
+      {
+        if(#0#1 =={core::num::==}{(core::Object) → core::bool} #C9 && #0#0.{core::Map::containsKey}(#C7){(core::Object?) → core::bool} && (let final core::String? #t27 = #0#0.{core::Map::[]}(#C7){(core::Object?) → core::String?} in true)) {
+          #t26 = 1;
+          break #L2;
+        }
+      }
+      {
+        if(#0#1.{core::num::<=}(#C7){(core::num) → core::bool}) {
+          #t26 = 0;
+          break #L2;
+        }
+      }
+      {
+        if(true) {
+          #t26 = 2;
+          break #L2;
+        }
+      }
+      throw new _in::ReachabilityError::•("`null` encountered as case in a switch expression with a non-nullable type.");
+    }
+  } =>#t26;
+static method main() → dynamic {
+  self::expect(0, self::switchList(core::_GrowableList::•<core::int>(0)));
+  self::expect(1, self::switchList(core::_GrowableList::_literal1<core::int>(0)));
+  self::expect(2, self::switchList(core::_GrowableList::_literal2<core::int>(0, 1)));
+  self::expect(0, self::switchList(new self::NegativeLengthList::•<core::int>(core::_GrowableList::•<core::int>(0))));
+  self::expect(1, self::switchList(new self::NegativeLengthList::•<core::int>(core::_GrowableList::_literal1<core::int>(0))));
+  self::expect(2, self::switchList(new self::NegativeLengthList::•<core::int>(core::_GrowableList::_literal2<core::int>(0, 1))));
+  self::expect(0, self::switchMap(<core::int, core::String>{}));
+  self::expect(1, self::switchMap(<core::int, core::String>{0: ""}));
+  self::expect(2, self::switchMap(<core::int, core::String>{1: ""}));
+  self::expect(0, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{})));
+  self::expect(1, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{0: ""})));
+  self::expect(2, self::switchMap(new self::NegativeLengthMap::•<core::int, core::String>(<core::int, core::String>{1: ""})));
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!(expected =={core::Object::==}{(core::Object) → core::bool} actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = "vm:prefer-inline"
+  #C2 = null
+  #C3 = core::pragma {name:#C1, options:#C2}
+  #C4 = ""
+  #C5 = true
+  #C6 = static-tearoff col::ListMixin::_compareAny
+  #C7 = 0
+  #C8 = 2
+  #C9 = 1
+}
+
+Extra constant evaluation status:
+Evaluated: InstanceInvocation @ org-dartlang-sdk:///sdk/lib/collection/list.dart:492:12 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-sdk:///sdk/lib/collection/list.dart:500:12 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-sdk:///sdk/lib/collection/list.dart:512:12 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-sdk:///sdk/lib/collection/list.dart:524:12 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-testcase:///negative_length.dart:12:41 -> IntConstant(-1)
+Evaluated: InstanceInvocation @ org-dartlang-testcase:///negative_length.dart:30:40 -> IntConstant(-1)
+Extra constant evaluation: evaluated: 1415, effectively constant: 6
diff --git a/pkg/kernel/lib/src/ast/patterns.dart b/pkg/kernel/lib/src/ast/patterns.dart
index c454508c18e..e0acdccb817 100644
--- a/pkg/kernel/lib/src/ast/patterns.dart
+++ b/pkg/kernel/lib/src/ast/patterns.dart
@@ -479,8 +479,9 @@ class ListPattern extends Pattern {
 
   /// The method used to check the `length` of the list.
   ///
-  /// If this pattern has a rest pattern, this is an `operator >=` method.
-  /// Otherwise this is an `operator ==` method.
+  /// If this pattern has a rest pattern, this is an `operator >=` method. If
+  /// this is the empty list pattern, this an `operator <=` method. Otherwise
+  /// this is an `operator ==` method.
   ///
   /// This is set during inference.
   Procedure get lengthCheckTarget => lengthCheckTargetReference!.asProcedure;
@@ -952,8 +953,9 @@ class MapPattern extends Pattern {
 
   /// Reference to the method used to check the `length` of the map.
   ///
-  /// If this pattern has a rest pattern, this is an `operator >=` method.
-  /// Otherwise this is an `operator ==` method.
+  /// If this pattern has a rest pattern, this is an `operator >=` method. If
+  /// this is the empty map pattern, this an `operator <=` method. Otherwise
+  /// this is an `operator ==` method.
   ///
   /// This is set during inference.
   Reference? lengthCheckTargetReference;
@@ -1009,7 +1011,7 @@ class MapPattern extends Pattern {
   /// The method used to check the `length` of the map.
   ///
   /// If this pattern has a rest pattern, this is an `operator >=` method.
-  /// Otherwise this is an `operator ==` method.
+  /// Otherwise this is an `operator <=` method.
   ///
   /// This is set during inference.
   Procedure get lengthCheckTarget => lengthCheckTargetReference!.asProcedure;