Elements. Remove DefaultParameterFragmentImpl.

Change-Id: I5fcfb0dedb634e052024fe3a41a704501a022f81
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/437583
Commit-Queue: Konstantin Shcheglov <[email protected]>
Reviewed-by: Paul Berry <[email protected]>

Author: scheglov

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

@@ -110,7 +110,7 @@ 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 = 483;
+  static const int DATA_VERSION = 484;
 
   /// 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/ast/utilities.dart

@@ -10,7 +10,6 @@ import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/exception/exception.dart';
 import 'package:analyzer/src/dart/ast/ast.dart';
-import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/generated/engine.dart' show AnalysisEngine;
 
 export 'package:analyzer/src/dart/ast/constant_evaluator.dart';
@@ -546,11 +545,7 @@ class NodeReplacer extends ThrowingAstVisitor<bool> {
     } else if (identical(node.defaultValue, _oldNode)) {
       node.defaultValue = _newNode as ExpressionImpl;
       var parameterElement = node.declaredFragment;
-      if (parameterElement is DefaultParameterFragmentImpl) {
-        parameterElement.constantInitializer = _newNode;
-      } else if (parameterElement is DefaultFieldFormalParameterElementImpl) {
-        parameterElement.constantInitializer = _newNode;
-      }
+      parameterElement?.constantInitializer = _newNode;
       return true;
     }
     return visitNode(node);

pkg/analyzer/lib/src/dart/constant/evaluation.dart

@@ -93,24 +93,22 @@ class ConstantEvaluationEngine {
 
     var library = constant.library as LibraryElementImpl;
     if (constant is FormalParameterFragmentImpl) {
-      if (constant is ConstVariableFragment) {
-        var defaultValue = constant.constantInitializer;
-        if (defaultValue != null) {
-          var diagnosticListener = RecordingDiagnosticListener();
-          var diagnosticReporter = DiagnosticReporter(
-            diagnosticListener,
-            constant.source!,
-          );
-          var constantVisitor = ConstantVisitor(
-            this,
-            library,
-            diagnosticReporter,
-          );
-          var dartConstant = constantVisitor.evaluateConstant(defaultValue);
-          constant.evaluationResult = dartConstant;
-        } else {
-          constant.evaluationResult = _nullObject(library);
-        }
+      var defaultValue = constant.constantInitializer;
+      if (defaultValue != null) {
+        var diagnosticListener = RecordingDiagnosticListener();
+        var diagnosticReporter = DiagnosticReporter(
+          diagnosticListener,
+          constant.source!,
+        );
+        var constantVisitor = ConstantVisitor(
+          this,
+          library,
+          diagnosticReporter,
+        );
+        var dartConstant = constantVisitor.evaluateConstant(defaultValue);
+        constant.evaluationResult = dartConstant;
+      } else {
+        constant.evaluationResult = _nullObject(library);
       }
     } else if (constant is VariableFragmentImpl) {
       var constantInitializer = constant.constantInitializer;

pkg/analyzer/lib/src/dart/constant/utilities.dart

@@ -198,10 +198,9 @@ class ConstantFinder extends RecursiveAstVisitor<void> {
                 !element.isStatic)) {
       constantsToCompute.add(element);
       // Fill error nodes.
-      if (element is ConstVariableFragment) {
-        var constElement = element as ConstVariableFragment;
+      if (element.constantInitializer case var constantInitializer?) {
         configuration.addErrorNode(
-          fromElement: constElement.constantInitializer,
+          fromElement: constantInitializer,
           fromAst: node.initializer,
         );
       }

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

@@ -481,24 +481,17 @@ class ClassElementImpl extends InterfaceElementImpl implements ClassElement {
           var formalParameterElements = <FormalParameterElementImpl>[];
           var superInvocationArguments = <ExpressionImpl>[];
           for (var superFormalParameter in superConstructor.formalParameters) {
-            FormalParameterFragmentImpl formalParameterFragment;
-            if (superFormalParameter.firstFragment
-                case ConstVariableFragment constVariable) {
-              // TODO(scheglov): Maybe stop making this distinction
-              formalParameterFragment = DefaultParameterFragmentImpl(
+            var formalParameterFragment = FormalParameterFragmentImpl(
                 nameOffset: -1,
                 name2: superFormalParameter.name3,
                 nameOffset2: null,
                 parameterKind: superFormalParameter.parameterKind,
-              )..constantInitializer = constVariable.constantInitializer;
-            } else {
-              formalParameterFragment = FormalParameterFragmentImpl(
-                nameOffset: -1,
-                name2: superFormalParameter.name3,
-                nameOffset2: null,
-                parameterKind: superFormalParameter.parameterKind,
-              );
-            }
+              )
+              ..constantInitializer =
+                  superFormalParameter
+                      .baseElement
+                      .firstFragment
+                      .constantInitializer;
 
             formalParameterFragment.isConst = superFormalParameter.isConst;
             formalParameterFragment.isFinal = superFormalParameter.isFinal;
@@ -1178,10 +1171,7 @@ mixin ConstVariableFragment implements FragmentImpl, ConstantEvaluationTarget {
       var library = this.library;
       // TODO(scheglov): https://github.com/dart-lang/sdk/issues/47915
       if (library == null) {
-        throw StateError(
-          '[library: null][this: ($runtimeType) $this]'
-          '[enclosingElement: $enclosingElement3]',
-        );
+        return null;
       }
       computeConstants(
         declaredVariables: context.declaredVariables,
@@ -1217,24 +1207,6 @@ class DefaultFieldFormalParameterElementImpl
   }
 }
 
-/// A [FormalParameterFragmentImpl] for parameters that have an initializer.
-class DefaultParameterFragmentImpl extends FormalParameterFragmentImpl
-    with ConstVariableFragment {
-  /// Initialize a newly created parameter element to have the given [name] and
-  /// [nameOffset].
-  DefaultParameterFragmentImpl({
-    required super.nameOffset,
-    required super.name2,
-    required super.nameOffset2,
-    required super.parameterKind,
-  });
-
-  @override
-  String? get defaultValueCode {
-    return constantInitializer?.toSource();
-  }
-}
-
 class DefaultSuperFormalParameterElementImpl
     extends SuperFormalParameterFragmentImpl
     with ConstVariableFragment {
@@ -3424,7 +3396,9 @@ class FormalParameterFragmentImpl extends VariableFragmentImpl
   FormalParameterFragmentImpl get declaration => this;
 
   @override
-  String? get defaultValueCode => null;
+  String? get defaultValueCode {
+    return constantInitializer?.toSource();
+  }
 
   @override
   FormalParameterElementImpl get element {
@@ -10387,6 +10361,7 @@ abstract class VariableElementOrMember
 }
 
 abstract class VariableFragmentImpl extends FragmentImpl
+    with ConstVariableFragment
     implements
         VariableElementOrMember,
         AnnotatableFragmentImpl,
@@ -10398,15 +10373,6 @@ abstract class VariableFragmentImpl extends FragmentImpl
   /// [offset].
   VariableFragmentImpl({required super.nameOffset});
 
-  /// If this element represents a constant variable, and it has an initializer,
-  /// a copy of the initializer for the constant.  Otherwise `null`.
-  ///
-  /// Note that in correct Dart code, all constant variables must have
-  /// initializers.  However, analyzer also needs to handle incorrect Dart code,
-  /// in which case there might be some constant variables that lack
-  /// initializers.
-  ExpressionImpl? get constantInitializer => null;
-
   @override
   VariableFragmentImpl get declaration => this;
 
@@ -10416,18 +10382,6 @@ abstract class VariableFragmentImpl extends FragmentImpl
   @override
   VariableElementImpl get element;
 
-  /// Return the result of evaluating this variable's initializer as a
-  /// compile-time constant expression, or `null` if this variable is not a
-  /// 'const' variable, if it does not have an initializer, or if the
-  /// compilation unit containing the variable has not been resolved.
-  Constant? get evaluationResult => null;
-
-  /// Set the result of evaluating this variable's initializer as a compile-time
-  /// constant expression to the given [result].
-  set evaluationResult(Constant? result) {
-    throw StateError("Invalid attempt to set a compile-time constant result");
-  }
-
   @override
   bool get hasImplicitType {
     return hasModifier(Modifier.IMPLICIT_TYPE);
@@ -10458,9 +10412,6 @@ abstract class VariableFragmentImpl extends FragmentImpl
     setModifier(Modifier.CONST, isConst);
   }
 
-  @override
-  bool get isConstantEvaluated => true;
-
   /// Set whether this variable is external.
   set isExternal(bool isExternal) {
     setModifier(Modifier.EXTERNAL, isExternal);
@@ -10502,9 +10453,6 @@ abstract class VariableFragmentImpl extends FragmentImpl
   void appendTo(ElementDisplayStringBuilder builder) {
     builder.writeVariableElement(this);
   }
-
-  @override
-  DartObject? computeConstantValue() => null;
 }
 
 mixin WrappedElementMixin implements ElementImpl {

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

@@ -459,7 +459,7 @@ class ResolutionVisitor extends RecursiveAstVisitor<void> {
           nameOffset2: nameOffset2,
         )..constantInitializer = node.defaultValue;
       } else {
-        fragment = DefaultParameterFragmentImpl(
+        fragment = FormalParameterFragmentImpl(
           nameOffset: nameOffset2 ?? -1,
           parameterKind: node.kind,
           name2: name2,

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

@@ -2392,7 +2392,7 @@ class ResolverVisitor extends ThrowingAstVisitor<void>
       popRewrite();
     }
 
-    if (fragment is DefaultParameterFragmentImpl && node.isOfLocalFunction) {
+    if (node.isOfLocalFunction) {
       fragment.constantInitializer = defaultValue;
     }
   }

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

@@ -450,7 +450,7 @@ class AstBinaryReader {
     );
 
     var nonDefaultElement = parameter.declaredFragment!;
-    var fragment = DefaultParameterFragmentImpl(
+    var fragment = FormalParameterFragmentImpl(
       nameOffset: nonDefaultElement.nameOffset,
       name2: nonDefaultElement.name2,
       nameOffset2: nonDefaultElement.nameOffset2,