Update shared analysis of object patterns to match spec.

In
ce01d330d7,
the patterns spec was changed so that if an object pattern's type
resolves to `dynamic` or `Never`, no getters are looked up during
static analysis, and the getter type is simply presumed to be
`dynamic` or `Never`, respectively.

Also, the parameter `requiredType` of `analyzeObjectPattern` is
removed (is was not needed, and the caller always passed `null`).

Finally, the test artifact `ObjectPatternRequiredType` is removed in
favor of just using a PrimaryType directly.  This makes the tests a
little bit more compact.

Change-Id: I6fcef8dab8250905e1d37308bbdc82a4fd65f52c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/270982
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

pkg/_fe_analyzer_shared/lib/src/type_inference/type_analyzer.dart

@@ -697,16 +697,23 @@ mixin TypeAnalyzer<
     Type matchedType,
     MatchContext<Node, Expression, Pattern, Type, Variable> context,
     Pattern node, {
-    required Type? requiredType,
     required List<RecordPatternField<Node, Pattern>> fields,
   }) {
     _reportDuplicateRecordPatternFields(fields);
 
-    requiredType ??= downwardInferObjectPatternRequiredType(
+    Type requiredType = downwardInferObjectPatternRequiredType(
       matchedType: matchedType,
       pattern: node,
     );
 
+    // If the required type is `dynamic` or `Never`, then every getter is
+    // treated as having the same type.
+    Type? overridePropertyGetType;
+    if (typeOperations.isDynamic(requiredType) ||
+        typeOperations.isNever(requiredType)) {
+      overridePropertyGetType = requiredType;
+    }
+
     Node? irrefutableContext = context.irrefutableContext;
     if (irrefutableContext != null &&
         !typeOperations.isAssignableTo(matchedType, requiredType)) {
@@ -720,10 +727,11 @@ mixin TypeAnalyzer<
 
     // Stack: ()
     for (RecordPatternField<Node, Pattern> field in fields) {
-      Type propertyType = resolveObjectPatternPropertyGet(
-        receiverType: requiredType,
-        field: field,
-      );
+      Type propertyType = overridePropertyGetType ??
+          resolveObjectPatternPropertyGet(
+            receiverType: requiredType,
+            field: field,
+          );
       dispatchPattern(propertyType, context, field.pattern);
     }
     // Stack: (n * Pattern) where n = fields.length

pkg/_fe_analyzer_shared/test/mini_ast.dart

@@ -265,11 +265,15 @@ Statement match(Pattern pattern, Expression initializer,
         isLate: isLate, isFinal: isFinal, location: computeLocation());
 
 Pattern objectPattern({
-  required ObjectPatternRequiredType requiredType,
+  required String requiredType,
   required List<RecordPatternField> fields,
 }) {
+  var parsedType = Type(requiredType);
+  if (parsedType is! PrimaryType) {
+    fail('Expected a primary type, got $parsedType');
+  }
   return _ObjectPattern(
-    requiredType: requiredType,
+    requiredType: parsedType,
     fields: fields,
     location: computeLocation(),
   );
@@ -754,6 +758,7 @@ class MiniAstOperations
     'int? <: Object': false,
     'int? <: Object?': true,
     'List<int> <: Object': true,
+    'Never <: Object': true,
     'Never <: Object?': true,
     'Null <: double?': true,
     'Null <: int': false,
@@ -881,7 +886,11 @@ class MiniAstOperations
   };
 
   static final Map<String, Type> _coreDownwardInferenceResults = {
+    'dynamic <: int': Type('dynamic'),
+    'int <: num': Type('int'),
     'List <: Iterable<int>': Type('List<int>'),
+    'Never <: int': Type('Never'),
+    'num <: int': Type('num'),
   };
 
   static final Map<String, Type> _coreNormalizeResults = {
@@ -1155,27 +1164,6 @@ class Node {
   String toString() => 'Node#$id';
 }
 
-/// Either the type, or the name of a type constructor.
-class ObjectPatternRequiredType {
-  final Type? type;
-  final String? name;
-
-  ObjectPatternRequiredType.name(this.name) : type = null;
-
-  ObjectPatternRequiredType.type(String type)
-      : type = Type(type),
-        name = null;
-
-  @override
-  String toString() {
-    if (type != null) {
-      return '(type: $type)';
-    } else {
-      return '(name: $name)';
-    }
-  }
-}
-
 abstract class Pattern extends Node
     with PossiblyGuardedPattern
     implements ListPatternElement {
@@ -3239,11 +3227,12 @@ class _MiniAstTypeAnalyzer
     required Type matchedType,
     required covariant _ObjectPattern pattern,
   }) {
-    var name = pattern.requiredType.name;
-    if (name == null) {
-      fail('Expected type constructor name at ${pattern.location}');
+    var requiredType = pattern.requiredType;
+    if (requiredType.args.isNotEmpty) {
+      return requiredType;
+    } else {
+      return typeOperations.downwardInfer(requiredType.name, matchedType);
     }
-    return typeOperations.downwardInfer(name, matchedType);
   }
 
   void finish() {
@@ -3675,7 +3664,7 @@ class _NullLiteral extends Expression {
 }
 
 class _ObjectPattern extends Pattern {
-  final ObjectPatternRequiredType requiredType;
+  final PrimaryType requiredType;
   final List<RecordPatternField> fields;
 
   _ObjectPattern({
@@ -3686,7 +3675,7 @@ class _ObjectPattern extends Pattern {
 
   @override
   Type computeSchema(Harness h) {
-    return h.typeAnalyzer.analyzeObjectPatternSchema(requiredType.type!);
+    return h.typeAnalyzer.analyzeObjectPatternSchema(requiredType);
   }
 
   @override
@@ -3705,9 +3694,8 @@ class _ObjectPattern extends Pattern {
     Type matchedType,
     SharedMatchContext context,
   ) {
-    var requiredType = h.typeAnalyzer.analyzeObjectPattern(
-        matchedType, context, this,
-        requiredType: this.requiredType.type, fields: fields);
+    var requiredType = h.typeAnalyzer
+        .analyzeObjectPattern(matchedType, context, this, fields: fields);
     h.irBuilder.atom(matchedType.type, Kind.type, location: location);
     h.irBuilder.atom(requiredType.type, Kind.type, location: location);
     h.irBuilder.apply(

pkg/_fe_analyzer_shared/test/type_inference/type_inference_test.dart

@@ -2090,7 +2090,7 @@ main() {
             ifCase(
               expr('A<int>').checkContext('?'),
               objectPattern(
-                requiredType: ObjectPatternRequiredType.name('B'),
+                requiredType: 'B',
                 fields: [
                   Var('foo', errorId: 'foo').pattern().recordField('foo'),
                 ],
@@ -2100,13 +2100,46 @@ main() {
                 'requiredType: B<int>), variables(foo), true, block(), noop)'),
           ]);
         });
+
+        test('dynamic type', () {
+          h.run([
+            ifCase(
+              expr('int').checkContext('?'),
+              objectPattern(
+                requiredType: 'dynamic',
+                fields: [
+                  Var('foo', errorId: 'foo').pattern().recordField('foo'),
+                ],
+              ),
+            ).checkIr('ifCase(expr(int), objectPattern(varPattern(foo, '
+                'matchedType: dynamic, staticType: dynamic), matchedType: int, '
+                'requiredType: dynamic), variables(foo), true, block(), noop)'),
+          ]);
+        });
+
+        test('Never type', () {
+          h.run([
+            ifCase(
+              expr('int').checkContext('?'),
+              objectPattern(
+                requiredType: 'Never',
+                fields: [
+                  Var('foo', errorId: 'foo').pattern().recordField('foo'),
+                ],
+              ),
+            ).checkIr('ifCase(expr(int), objectPattern(varPattern(foo, '
+                'matchedType: Never, staticType: Never), matchedType: int, '
+                'requiredType: Never), variables(foo), true, block(), noop)'),
+          ]);
+        });
+
         test('duplicate field name', () {
           h.addMember('A<int>', 'foo', 'int');
           h.run([
             ifCase(
               expr('A<int>'),
               objectPattern(
-                requiredType: ObjectPatternRequiredType.type('A<int>'),
+                requiredType: 'A<int>',
                 fields: [
                   Var('a', errorId: 'a').pattern().recordField('foo')
                     ..errorId = 'ORIGINAL',
@@ -2128,7 +2161,7 @@ main() {
           h.run([
             match(
               objectPattern(
-                requiredType: ObjectPatternRequiredType.type('num'),
+                requiredType: 'num',
                 fields: [
                   Var('foo').pattern().recordField('foo'),
                 ],
@@ -2145,7 +2178,7 @@ main() {
           h.run([
             (match(
               objectPattern(
-                requiredType: ObjectPatternRequiredType.type('int'),
+                requiredType: 'int',
                 fields: [
                   Var('foo').pattern().recordField('foo'),
                 ],

pkg/analyzer/lib/src/dart/ast/ast.dart

@@ -9452,7 +9452,6 @@ class ObjectPatternImpl extends DartPatternImpl implements ObjectPattern {
       matchedType,
       context,
       this,
-      requiredType: null,
       fields: resolverVisitor.buildSharedRecordPatternFields(fields),
     );
   }