[cfe] fix order of pattern fields

Fixes #50826

Change-Id: I5e71c4dd0e4f937c4570e4851cd4c1e3446d888a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/277003
Commit-Queue: Chloe Stefantsova <cstefantsova@google.com>
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

@@ -8337,6 +8337,13 @@ class BodyBuilder extends StackListenerImpl
         // TODO(cstefantsova): Report an error.
       }
     }
+    if (fields != null) {
+      for (int i = 0, j = fields.length - 1; i < j; i++, j--) {
+        NamedPattern field = fields[i];
+        fields[i] = fields[j];
+        fields[j] = field;
+      }
+    }
     push(fields ?? NullValue.PatternList);
   }
 

pkg/front_end/testcases/patterns/fields_order.dart

@@ -0,0 +1,16 @@
+// Copyright (c) 2022, 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.
+
+class A {
+  String get foo => "foo";
+  Object? get bar => null;
+}
+
+test(dynamic x) {
+  if (x case A(foo: "", bar: String y as String)) {
+    return y;
+  } else {
+    return null;
+  }
+}

pkg/front_end/testcases/patterns/fields_order.dart.strong.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+  get foo() → core::String
+    return "foo";
+  get bar() → core::Object?
+    return null;
+}
+static method test(dynamic x) → dynamic {
+  final dynamic #t1 = x;
+  final core::bool #t2 = true;
+  final dynamic #t3 = #t1;
+  if(#t3 is self::A) {
+    final core::String #t4 = #t3{self::A}.{self::A::foo}{core::String};
+    final core::Object? #t5 = #t3{self::A}.{self::A::bar}{core::Object?};
+    if(#t4 =={core::String::==}{(core::Object) → core::bool} "") {
+      final core::String #t6 = #t5 as{ForNonNullableByDefault} core::String;
+      final core::String #t7 = #t6;
+      if(#t7 is core::String) {
+        #t2 = false;
+        {
+          core::String y = #t7{core::String};
+          {
+            return y;
+          }
+        }
+      }
+    }
+  }
+  if(#t2) {
+    return null;
+  }
+}

pkg/front_end/testcases/patterns/fields_order.dart.strong.transformed.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+  get foo() → core::String
+    return "foo";
+  get bar() → core::Object?
+    return null;
+}
+static method test(dynamic x) → dynamic {
+  final dynamic #t1 = x;
+  final core::bool #t2 = true;
+  final dynamic #t3 = #t1;
+  if(#t3 is self::A) {
+    final core::String #t4 = #t3{self::A}.{self::A::foo}{core::String};
+    final core::Object? #t5 = #t3{self::A}.{self::A::bar}{core::Object?};
+    if(#t4 =={core::String::==}{(core::Object) → core::bool} "") {
+      final core::String #t6 = #t5 as{ForNonNullableByDefault} core::String;
+      final core::String #t7 = #t6;
+      if(#t7 is core::String) {
+        #t2 = false;
+        {
+          core::String y = #t7{core::String};
+          {
+            return y;
+          }
+        }
+      }
+    }
+  }
+  if(#t2) {
+    return null;
+  }
+}

pkg/front_end/testcases/patterns/fields_order.dart.textual_outline.expect

@@ -0,0 +1,6 @@
+class A {
+  String get foo => "foo";
+  Object? get bar => null;
+}
+
+test(dynamic x) {}

pkg/front_end/testcases/patterns/fields_order.dart.textual_outline_modelled.expect

@@ -0,0 +1,6 @@
+class A {
+  Object? get bar => null;
+  String get foo => "foo";
+}
+
+test(dynamic x) {}

pkg/front_end/testcases/patterns/fields_order.dart.weak.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+  get foo() → core::String
+    return "foo";
+  get bar() → core::Object?
+    return null;
+}
+static method test(dynamic x) → dynamic {
+  final dynamic #t1 = x;
+  final core::bool #t2 = true;
+  final dynamic #t3 = #t1;
+  if(#t3 is self::A) {
+    final core::String #t4 = #t3{self::A}.{self::A::foo}{core::String};
+    final core::Object? #t5 = #t3{self::A}.{self::A::bar}{core::Object?};
+    if(#t4 =={core::String::==}{(core::Object) → core::bool} "") {
+      final core::String #t6 = #t5 as{ForNonNullableByDefault} core::String;
+      final core::String #t7 = #t6;
+      if(#t7 is core::String) {
+        #t2 = false;
+        {
+          core::String y = #t7{core::String};
+          {
+            return y;
+          }
+        }
+      }
+    }
+  }
+  if(#t2) {
+    return null;
+  }
+}

pkg/front_end/testcases/patterns/fields_order.dart.weak.modular.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+  get foo() → core::String
+    return "foo";
+  get bar() → core::Object?
+    return null;
+}
+static method test(dynamic x) → dynamic {
+  final dynamic #t1 = x;
+  final core::bool #t2 = true;
+  final dynamic #t3 = #t1;
+  if(#t3 is self::A) {
+    final core::String #t4 = #t3{self::A}.{self::A::foo}{core::String};
+    final core::Object? #t5 = #t3{self::A}.{self::A::bar}{core::Object?};
+    if(#t4 =={core::String::==}{(core::Object) → core::bool} "") {
+      final core::String #t6 = #t5 as{ForNonNullableByDefault} core::String;
+      final core::String #t7 = #t6;
+      if(#t7 is core::String) {
+        #t2 = false;
+        {
+          core::String y = #t7{core::String};
+          {
+            return y;
+          }
+        }
+      }
+    }
+  }
+  if(#t2) {
+    return null;
+  }
+}

pkg/front_end/testcases/patterns/fields_order.dart.weak.outline.expect

@@ -0,0 +1,14 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    ;
+  get foo() → core::String
+    ;
+  get bar() → core::Object?
+    ;
+}
+static method test(dynamic x) → dynamic
+  ;

pkg/front_end/testcases/patterns/fields_order.dart.weak.transformed.expect

@@ -0,0 +1,38 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+  get foo() → core::String
+    return "foo";
+  get bar() → core::Object?
+    return null;
+}
+static method test(dynamic x) → dynamic {
+  final dynamic #t1 = x;
+  final core::bool #t2 = true;
+  final dynamic #t3 = #t1;
+  if(#t3 is self::A) {
+    final core::String #t4 = #t3{self::A}.{self::A::foo}{core::String};
+    final core::Object? #t5 = #t3{self::A}.{self::A::bar}{core::Object?};
+    if(#t4 =={core::String::==}{(core::Object) → core::bool} "") {
+      final core::String #t6 = #t5 as{ForNonNullableByDefault} core::String;
+      final core::String #t7 = #t6;
+      if(#t7 is core::String) {
+        #t2 = false;
+        {
+          core::String y = #t7{core::String};
+          {
+            return y;
+          }
+        }
+      }
+    }
+  }
+  if(#t2) {
+    return null;
+  }
+}