Elements. Move extension type properties from fragment to element

The `typeErasure`, `primaryConstructor`, and `representation` fields are
properties of the extension type as a whole, not of any individual
declaration fragment.

This commit moves `typeErasure` from `ExtensionTypeFragmentImpl` to
`ExtensionTypeElementImpl` to better align the element model with this
concept.

As part of this refactoring, the `primaryConstructor` and
`representation` getters on `ExtensionTypeFragment` are now deprecated.
Clients should access these properties directly from the
`ExtensionTypeElement`, which serves as the single source of truth. All
internal call sites have been updated accordingly.

Change-Id: I359572c6f7fe1d562fadfb60873a6e34aed0e5ee
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/445580
Reviewed-by: Paul Berry <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: scheglov

pkg/analyzer/CHANGELOG.md

@@ -12,6 +12,8 @@
 * Deprecate `InterfaceFragment.interfaces`, use `InterfaceElement.interfaces` instead.
 * Deprecate `InterfaceFragment.mixins`, use `InterfaceElement.mixins` instead.
 * Deprecate `InterfaceFragment.supertype`, use `InterfaceElement.supertype` instead.
+* Deprecate `ExtensionTypeFragment.primaryConstructor`, use `ExtensionTypeElement.primaryConstructor`.
+* Deprecate `ExtensionTypeFragment.representation`, use `ExtensionTypeElement.representation`.
 
 ## 8.1.1
 * Fix for `EnumSet` usage when compiled to JavaScript.

pkg/analyzer/api.txt

@@ -3588,9 +3588,9 @@ package:analyzer/dart/element/element.dart:
     element (getter: ExtensionTypeElement)
     nextFragment (getter: ExtensionTypeFragment?)
     previousFragment (getter: ExtensionTypeFragment?)
-    primaryConstructor (getter: ConstructorFragment)
+    primaryConstructor (getter: ConstructorFragment, deprecated)
     primaryConstructor2 (getter: ConstructorFragment, deprecated)
-    representation (getter: FieldFragment)
+    representation (getter: FieldFragment, deprecated)
     representation2 (getter: FieldFragment, deprecated)
   FieldElement (class extends Object implements PropertyInducingElement):
     new (constructor: FieldElement Function())

pkg/analyzer/lib/dart/element/element.dart

@@ -1506,13 +1506,15 @@ abstract class ExtensionTypeFragment implements InterfaceFragment {
   ExtensionTypeFragment? get previousFragment;
 
   /// The primary constructor of this extension.
+  @Deprecated('Use ExtensionTypeElement.primaryConstructor instead')
   ConstructorFragment get primaryConstructor;
 
   /// The primary constructor of this extension.
   @Deprecated('Use primaryConstructor instead')
   ConstructorFragment get primaryConstructor2;
 
   /// The representation of this extension.
+  @Deprecated('Use ExtensionTypeElement.representation instead')
   FieldFragment get representation;
 
   /// The representation of this extension.

pkg/analyzer/lib/src/dart/analysis/driver.dart

@@ -109,7 +109,7 @@ testFineAfterLibraryAnalyzerHook;
 // TODO(scheglov): Clean up the list of implicitly analyzed files.
 class AnalysisDriver {
   /// The version of data format, should be incremented on every format change.
-  static const int DATA_VERSION = 521;
+  static const int DATA_VERSION = 522;
 
   /// The number of exception contexts allowed to write. Once this field is
   /// zero, we stop writing any new exception contexts in this process.

pkg/analyzer/lib/src/dart/element/element.dart

@@ -2455,6 +2455,8 @@ class ExtensionTypeElementImpl extends InterfaceElementImpl
   @override
   final ExtensionTypeFragmentImpl firstFragment;
 
+  late DartType _typeErasure;
+
   ExtensionTypeElementImpl(this.reference, this.firstFragment) {
     reference.element = this;
     firstFragment.element = this;
@@ -2501,7 +2503,7 @@ class ExtensionTypeElementImpl extends InterfaceElementImpl
 
   @override
   ConstructorElement get primaryConstructor {
-    return firstFragment.primaryConstructor.element;
+    return constructors.first;
   }
 
   @Deprecated('Use primaryConstructor instead')
@@ -2510,9 +2512,14 @@ class ExtensionTypeElementImpl extends InterfaceElementImpl
     return primaryConstructor;
   }
 
+  FieldFormalParameterElementImpl get primaryFormalParameter {
+    return primaryConstructor.formalParameters.first
+        as FieldFormalParameterElementImpl;
+  }
+
   @override
   FieldElementImpl get representation {
-    return firstFragment.representation.element;
+    return fields.first;
   }
 
   @Deprecated('Use representation instead')
@@ -2522,7 +2529,14 @@ class ExtensionTypeElementImpl extends InterfaceElementImpl
   }
 
   @override
-  DartType get typeErasure => firstFragment.typeErasure;
+  DartType get typeErasure {
+    _ensureReadResolution();
+    return _typeErasure;
+  }
+
+  set typeErasure(DartType value) {
+    _typeErasure = value;
+  }
 
   @override
   T? accept<T>(ElementVisitor2<T> visitor) {
@@ -2552,8 +2566,6 @@ class ExtensionTypeFragmentImpl extends InterfaceFragmentImpl
   @override
   late final ExtensionTypeElementImpl element;
 
-  late DartType typeErasure;
-
   /// Whether the element has direct or indirect reference to itself,
   /// in representation.
   bool hasRepresentationSelfReference = false;
@@ -2572,6 +2584,7 @@ class ExtensionTypeFragmentImpl extends InterfaceFragmentImpl
   ExtensionTypeFragmentImpl? get previousFragment =>
       super.previousFragment as ExtensionTypeFragmentImpl?;
 
+  @Deprecated('Use ExtensionTypeElement.primaryConstructor instead')
   @override
   ConstructorFragmentImpl get primaryConstructor {
     return constructors.first;
@@ -2581,6 +2594,7 @@ class ExtensionTypeFragmentImpl extends InterfaceFragmentImpl
   @override
   ConstructorFragmentImpl get primaryConstructor2 => primaryConstructor;
 
+  @Deprecated('Use ExtensionTypeElement.representation instead')
   @override
   FieldFragmentImpl get representation {
     return fields.first;

pkg/analyzer/lib/src/dart/resolver/resolution_visitor.dart

@@ -596,10 +596,12 @@ class ResolutionVisitor extends RecursiveAstVisitor<void> {
 
     _setOrCreateMetadataElements(fragment, node.metadata);
 
-    _setOrCreateMetadataElements(
-      fragment.representation,
-      node.representation.fieldMetadata,
-    );
+    if (identical(element.firstFragment, fragment)) {
+      _setOrCreateMetadataElements(
+        element.representation.firstFragment,
+        node.representation.fieldMetadata,
+      );
+    }
 
     _withElementWalker(ElementWalker.forExtensionType(fragment), () {
       _withNameScope(() {

pkg/analyzer/lib/src/error/duplicate_definition_verifier.dart

@@ -799,9 +799,10 @@ class MemberDuplicateDefinitionVerifier {
 
   void _checkExtensionType(ExtensionTypeDeclarationImpl node) {
     var fragment = node.declaredFragment!;
-    var firstFragment = fragment.element.firstFragment;
-    var primaryConstructorName = firstFragment.constructors.first.name;
-    var representationGetter = firstFragment.representation.element.getter!;
+    var element = fragment.element;
+    var firstFragment = element.firstFragment;
+    var primaryConstructorName = element.primaryConstructor.name!;
+    var representationGetter = element.representation.getter!;
     var elementContext = _getElementContext(firstFragment);
     elementContext.constructorNames.add(primaryConstructorName);
     if (representationGetter.name case var getterName?) {

pkg/analyzer/lib/src/summary2/bundle_reader.dart

@@ -630,6 +630,7 @@ class LibraryReader {
       element.deferReadResolution(
         _createDeferredReadResolutionCallback((reader) {
           reader._addTypeParameters2(element.typeParameters);
+          element.typeErasure = reader.readRequiredType();
           element.interfaces = reader._readInterfaceTypeList();
         }),
       );
@@ -663,7 +664,6 @@ class LibraryReader {
             fragment.typeParameters,
           );
           fragment.metadata = reader._readMetadata();
-          fragment.typeErasure = reader.readRequiredType();
         },
       );
     });

pkg/analyzer/lib/src/summary2/bundle_writer.dart

@@ -367,6 +367,7 @@ class BundleWriter {
 
       _writeElementResolution(() {
         _resolutionSink.withTypeParameters(element.typeParameters, () {
+          _resolutionSink.writeType(element.typeErasure);
           _resolutionSink._writeTypeList(element.interfaces);
         });
       });
@@ -380,7 +381,6 @@ class BundleWriter {
       _sink.writeBool(fragment.hasImplementsSelfReference);
       _writeTypeParameters(fragment.typeParameters, () {
         _resolutionSink._writeMetadata(fragment.metadata);
-        _resolutionSink.writeType(fragment.typeErasure);
 
         // TODO(scheglov): consider reading lazily
         _sink.writeList(fragment.fields, _writeFieldFragment);

pkg/analyzer/lib/src/summary2/extension_type.dart

@@ -153,21 +153,16 @@ class _Node extends graph.Node<_Node> {
   void _evaluateWithType(TypeImpl type) {
     var typeSystem = element.library.typeSystem;
 
-    var representationFragment = element.firstFragment.representation;
-    var representationElement = representationFragment.element;
-    representationElement.type = type;
+    element.representation.type = type;
+    element.primaryFormalParameter.type = type;
 
-    element.firstFragment.typeErasure = type.extensionTypeErasure;
+    element.typeErasure = type.extensionTypeErasure;
     element.interfaces =
         element.interfaces
             .whereType<InterfaceType>()
             .where(typeSystem.isValidExtensionTypeSuperinterface)
             .toFixedList();
 
-    var primaryConstructor = element.constructors.first;
-    var primaryFormalParameter = primaryConstructor.formalParameters.first;
-    primaryFormalParameter as FieldFormalParameterElementImpl;
-    primaryFormalParameter.type = type;
     isEvaluated = true;
   }