Elements. Inline AugmentableFragment into FragmentImpl.

This required a few changes to duplicate declarations checking, so I
made a few related changes there. There are two main changes:

1. Record `ElementImpl`s as scope entries. Which is more precise, we
declare elements, not fragments.

2. Record getters and setters explicitly, move responsibility for
decomposing `PropertyInducingElement` this out of
`_checkDuplicateIdentifier()`, which IMHO makes it more cohesive.

Change-Id: I5eb117b3f830c1d1802c5f6fa836ff4324d4dc23
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/438841
Reviewed-by: Paul Berry <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

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

@@ -6234,6 +6234,9 @@ sealed class DeclarationImpl extends AnnotatedNodeImpl implements Declaration {
   /// Either or both of the [comment] and [metadata] can be `null` if the
   /// declaration doesn't have the corresponding attribute.
   DeclarationImpl({required super.comment, required super.metadata});
+
+  @override
+  FragmentImpl? get declaredFragment;
 }
 
 /// The declaration of a single identifier.
@@ -9602,7 +9605,7 @@ final class FieldDeclarationImpl extends ClassMemberImpl
   }
 
   @override
-  Fragment? get declaredFragment => null;
+  Null get declaredFragment => null;
 
   @generated
   @override
@@ -24498,7 +24501,7 @@ final class TopLevelVariableDeclarationImpl extends CompilationUnitMemberImpl
   }
 
   @override
-  Fragment? get declaredFragment => null;
+  Null get declaredFragment => null;
 
   @generated
   @override

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

@@ -74,17 +74,6 @@ abstract class AnnotatableFragmentImpl implements FragmentImpl, Annotatable {
   abstract MetadataImpl metadata;
 }
 
-/// Shared implementation for an augmentable [Fragment].
-mixin AugmentableFragment on FragmentImpl {
-  bool get isAugmentation {
-    return hasModifier(Modifier.AUGMENTATION);
-  }
-
-  set isAugmentation(bool value) {
-    setModifier(Modifier.AUGMENTATION, value);
-  }
-}
-
 class BindPatternVariableElementImpl extends PatternVariableElementImpl
     implements BindPatternVariableElement {
   BindPatternVariableElementImpl(super._wrappedElement);
@@ -2133,10 +2122,7 @@ abstract class ExecutableElementImpl extends FunctionTypedElementImpl
 }
 
 abstract class ExecutableFragmentImpl extends _ExistingFragmentImpl
-    with
-        AugmentableFragment,
-        DeferredResolutionReadingMixin,
-        TypeParameterizedFragmentMixin
+    with DeferredResolutionReadingMixin, TypeParameterizedFragmentMixin
     implements ExecutableFragment {
   /// A list containing all of the parameters defined by this executable
   /// element.
@@ -3608,6 +3594,14 @@ abstract class FragmentImpl implements Fragment {
     return enclosingElement3!.enclosingUnit;
   }
 
+  bool get isAugmentation {
+    return hasModifier(Modifier.AUGMENTATION);
+  }
+
+  set isAugmentation(bool value) {
+    setModifier(Modifier.AUGMENTATION, value);
+  }
+
   bool get isNonFunctionTypeAliasesEnabled {
     return library!.featureSet.isEnabled(Feature.nonfunction_type_aliases);
   }
@@ -4611,7 +4605,6 @@ recorded above.
 
 abstract class InstanceFragmentImpl extends _ExistingFragmentImpl
     with
-        AugmentableFragment,
         DeferredMembersReadingMixin,
         DeferredResolutionReadingMixin,
         TypeParameterizedFragmentMixin
@@ -8314,7 +8307,7 @@ class PrefixElementImpl extends ElementImpl implements PrefixElement {
   void visitChildren2<T>(ElementVisitor2<T> visitor) {}
 }
 
-class PrefixFragmentImpl implements PrefixFragment {
+class PrefixFragmentImpl extends FragmentImpl implements PrefixFragment {
   @override
   final LibraryFragmentImpl enclosingFragment;
 
@@ -8344,11 +8337,14 @@ class PrefixFragmentImpl implements PrefixFragment {
     required this.name2,
     required this.nameOffset2,
     required this.isDeferred,
-  });
+  }) : super(nameOffset: -1);
 
   @override
   List<Fragment> get children3 => const [];
 
+  @override
+  LibraryElementImpl? get library => libraryFragment.element;
+
   @override
   LibraryFragmentImpl get libraryFragment => enclosingFragment;
 }
@@ -8553,7 +8549,7 @@ abstract class PropertyInducingElementTypeInference {
 
 abstract class PropertyInducingFragmentImpl
     extends NonParameterVariableFragmentImpl
-    with AugmentableFragment, DeferredResolutionReadingMixin
+    with DeferredResolutionReadingMixin
     implements PropertyInducingFragment {
   @override
   final String? name2;
@@ -9474,10 +9470,7 @@ class TypeAliasElementImpl extends TypeDefiningElementImpl
 ///
 /// Clients may not extend, implement or mix-in this class.
 class TypeAliasFragmentImpl extends _ExistingFragmentImpl
-    with
-        AugmentableFragment,
-        DeferredResolutionReadingMixin,
-        TypeParameterizedFragmentMixin
+    with DeferredResolutionReadingMixin, TypeParameterizedFragmentMixin
     implements TypeAliasFragment {
   @override
   final String? name2;

pkg/analyzer/lib/src/diagnostic/diagnostic_factory.dart

@@ -9,6 +9,7 @@ import 'package:analyzer/diagnostic/diagnostic.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/source/source.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
+import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/diagnostic/diagnostic.dart';
 import 'package:analyzer/src/error/codes.dart';
 
@@ -44,30 +45,27 @@ class DiagnosticFactory {
     );
   }
 
-  /// Return a diagnostic indicating that [duplicateElement] reuses a name
+  /// Return a diagnostic indicating that [duplicateFragment] reuses a name
   /// already used by [originalElement].
   Diagnostic duplicateDefinition(
     DiagnosticCode code,
-    Element duplicateElement,
-    Element originalElement,
+    FragmentImpl duplicateFragment,
+    ElementImpl originalElement,
     List<Object> arguments,
   ) {
-    var duplicate = duplicateElement.nonSynthetic;
-    var duplicateFragment = duplicate.firstFragment;
-    var original = originalElement.nonSynthetic;
-    var originalFragment = original.firstFragment;
+    var originalFragment = originalElement.nonSynthetic.firstFragment;
     return Diagnostic.tmp(
       source: duplicateFragment.libraryFragment!.source,
       offset: duplicateFragment.nameOffset2 ?? -1,
-      length: duplicate.name3!.length,
+      length: duplicateFragment.name2!.length,
       diagnosticCode: code,
       arguments: arguments,
       contextMessages: [
         DiagnosticMessageImpl(
           filePath: originalFragment.libraryFragment!.source.fullName,
           message: "The first definition of this name.",
           offset: originalFragment.nameOffset2 ?? -1,
-          length: original.name3!.length,
+          length: originalElement.nonSynthetic.name3!.length,
           url: null,
         ),
       ],