Revert "[analyzer][null-aware-elements] Add NullAwareElement AST node"

This reverts commit 2bc2f89.

Reason for revert: breaks Flutter HHH

Original change's description:
> [analyzer][null-aware-elements] Add NullAwareElement AST node
>
> Closes #56267
>
> Part of #56266
> Part of #55949
>
> Change-Id: I7c79d6be312f579e95291f2c2d21e3f996500b87
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/376101
> Reviewed-by: Keerti Parthasarathy <[email protected]>
> Reviewed-by: Konstantin Shcheglov <[email protected]>
> Commit-Queue: Chloe Stefantsova <[email protected]>

Change-Id: I31e35eec14585818baccb1d34b823f7f2b6bc4f4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/376800
Auto-Submit: Konstantin Shcheglov <[email protected]>
Reviewed-by: Siva Annamalai <[email protected]>
Commit-Queue: Siva Annamalai <[email protected]>
Bot-Commit: Rubber Stamper <[email protected]>

Author: scheglov

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

@@ -180,7 +180,6 @@ export 'package:analyzer/src/dart/ast/ast.dart'
         NodeList,
         NormalFormalParameter,
         NullAssertPattern,
-        NullAwareElement,
         NullCheckPattern,
         NullLiteral,
         NullShortableExpression,

pkg/analyzer/lib/dart/ast/visitor.dart

@@ -559,10 +559,6 @@ class GeneralizingAstVisitor<R> implements AstVisitor<R> {
   @override
   R? visitNullAssertPattern(NullAssertPattern node) => visitDartPattern(node);
 
-  @override
-  R? visitNullAwareElement(NullAwareElement node) =>
-      visitCollectionElement(node);
-
   @override
   R? visitNullCheckPattern(NullCheckPattern node) => visitDartPattern(node);
 
@@ -1475,12 +1471,6 @@ class RecursiveAstVisitor<R> implements AstVisitor<R> {
     return null;
   }
 
-  @override
-  R? visitNullAwareElement(NullAwareElement node) {
-    node.visitChildren(this);
-    return null;
-  }
-
   @override
   R? visitNullCheckPattern(NullCheckPattern node) {
     node.visitChildren(this);
@@ -2219,9 +2209,6 @@ class SimpleAstVisitor<R> implements AstVisitor<R> {
   @override
   R? visitNullAssertPattern(NullAssertPattern node) => null;
 
-  @override
-  R? visitNullAwareElement(NullAwareElement node) => null;
-
   @override
   R? visitNullCheckPattern(NullCheckPattern node) => null;
 
@@ -2783,9 +2770,6 @@ class ThrowingAstVisitor<R> implements AstVisitor<R> {
   @override
   R? visitNullAssertPattern(NullAssertPattern node) => _throw(node);
 
-  @override
-  R? visitNullAwareElement(NullAwareElement node) => _throw(node);
-
   @override
   R? visitNullCheckPattern(NullCheckPattern node) => _throw(node);
 
@@ -3896,14 +3880,6 @@ class TimedAstVisitor<T> implements AstVisitor<T> {
     return result;
   }
 
-  @override
-  T? visitNullAwareElement(NullAwareElement node) {
-    stopwatch.start();
-    T? result = _baseVisitor.visitNullAwareElement(node);
-    stopwatch.stop();
-    return result;
-  }
-
   @override
   T? visitNullCheckPattern(NullCheckPattern node) {
     stopwatch.start();
@@ -4796,9 +4772,6 @@ class UnifyingAstVisitor<R> implements AstVisitor<R> {
   @override
   R? visitNullAssertPattern(NullAssertPattern node) => visitNode(node);
 
-  @override
-  R? visitNullAwareElement(NullAwareElement node) => visitNode(node);
-
   @override
   R? visitNullCheckPattern(NullCheckPattern node) => visitNode(node);
 

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

@@ -1442,8 +1442,6 @@ abstract class AstVisitor<R> {
 
   R? visitNullAssertPattern(NullAssertPattern node);
 
-  R? visitNullAwareElement(NullAwareElement node);
-
   R? visitNullCheckPattern(NullCheckPattern node);
 
   R? visitNullLiteral(NullLiteral node);
@@ -11270,47 +11268,31 @@ final class LogicalOrPatternImpl extends DartPatternImpl
 /// A single key/value pair in a map literal.
 ///
 ///    mapLiteralEntry ::=
-///        '?'? [Expression] ':' '?'? [Expression]
+///        [Expression] ':' [Expression]
 abstract final class MapLiteralEntry implements CollectionElement {
   /// The expression computing the key with which the value is associated.
   Expression get key;
 
-  /// The question prefix for the key that may present in null-aware map
-  /// entries.
-  Token? get keyQuestion;
-
   /// The colon that separates the key from the value.
   Token get separator;
 
   /// The expression computing the value that is associated with the key.
   Expression get value;
-
-  /// The question prefix for the value that may present in null-aware map
-  /// entries.
-  Token? get valueQuestion;
 }
 
 final class MapLiteralEntryImpl extends CollectionElementImpl
     implements MapLiteralEntry {
-  @override
-  final Token? keyQuestion;
-
   ExpressionImpl _key;
 
   @override
   final Token separator;
 
-  @override
-  final Token? valueQuestion;
-
   ExpressionImpl _value;
 
   /// Initializes a newly created map literal entry.
   MapLiteralEntryImpl({
-    required this.keyQuestion,
     required ExpressionImpl key,
     required this.separator,
-    required this.valueQuestion,
     required ExpressionImpl value,
   })  : _key = key,
         _value = value {
@@ -11319,7 +11301,7 @@ final class MapLiteralEntryImpl extends CollectionElementImpl
   }
 
   @override
-  Token get beginToken => keyQuestion ?? _key.beginToken;
+  Token get beginToken => _key.beginToken;
 
   @override
   Token get endToken => _value.endToken;
@@ -11340,10 +11322,8 @@ final class MapLiteralEntryImpl extends CollectionElementImpl
 
   @override
   ChildEntities get _childEntities => ChildEntities()
-    ..addToken('keyQuestion', keyQuestion)
     ..addNode('key', key)
     ..addToken('separator', separator)
-    ..addToken('valueQuestion', valueQuestion)
     ..addNode('value', value);
 
   @override
@@ -12839,66 +12819,6 @@ final class NullAssertPatternImpl extends DartPatternImpl
   }
 }
 
-/// A null-aware element in a list or set literal.
-///
-///    <nullAwareExpressionElement> ::= '?' <expression>
-abstract final class NullAwareElement implements CollectionElement {
-  /// The question mark before the expression.
-  Token get question;
-
-  /// The expression computing the value that is associated with the element.
-  Expression get value;
-}
-
-final class NullAwareElementImpl extends CollectionElementImpl
-    implements NullAwareElement {
-  @override
-  final Token question;
-
-  ExpressionImpl _value;
-
-  /// Initializes a newly created null-aware element.
-  NullAwareElementImpl({
-    required this.question,
-    required ExpressionImpl value,
-  }) : _value = value {
-    _becomeParentOf(_value);
-  }
-
-  @override
-  Token get beginToken => question;
-
-  @override
-  Token get endToken => _value.endToken;
-
-  @override
-  ExpressionImpl get value => _value;
-
-  set value(ExpressionImpl expression) {
-    _value = _becomeParentOf(expression);
-  }
-
-  @override
-  ChildEntities get _childEntities => ChildEntities()
-    ..addToken('question', question)
-    ..addNode('value', value);
-
-  @override
-  E? accept<E>(AstVisitor<E> visitor) => visitor.visitNullAwareElement(this);
-
-  @override
-  void resolveElement(
-      ResolverVisitor resolver, CollectionLiteralContext? context) {
-    // resolver.visitNullAwareElement(this, context: context);
-    resolver.pushRewrite(null);
-  }
-
-  @override
-  void visitChildren(AstVisitor visitor) {
-    _value.accept(visitor);
-  }
-}
-
 /// A null-check pattern.
 ///
 ///    nullCheckPattern ::=

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

@@ -984,12 +984,6 @@ class ToSourceVisitor implements AstVisitor<void> {
     sink.write(node.operator.lexeme);
   }
 
-  @override
-  void visitNullAwareElement(NullAwareElement node) {
-    sink.write(node.question.lexeme);
-    _visitNode(node.value);
-  }
-
   @override
   void visitNullCheckPattern(NullCheckPattern node) {
     _visitNode(node.pattern);

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

@@ -1114,13 +1114,6 @@ class AstComparator implements AstVisitor<bool> {
         isEqualTokens(node.operator, other.operator);
   }
 
-  @override
-  bool visitNullAwareElement(NullAwareElement node) {
-    NullAwareElement other = _other as NullAwareElement;
-    return isEqualTokens(node.question, other.question) &&
-        isEqualNodes(node.value, other.value);
-  }
-
   @override
   bool visitNullCheckPattern(NullCheckPattern node) {
     var other = _other as NullCheckPattern;
@@ -3049,15 +3042,6 @@ class NodeReplacer extends ThrowingAstVisitor<bool> {
     return visitNode(node);
   }
 
-  @override
-  bool visitNullAwareElement(NullAwareElement node) {
-    if (identical(node.value, _oldNode)) {
-      (node as NullAwareElementImpl).value = _newNode as ExpressionImpl;
-      return true;
-    }
-    return visitNode(node);
-  }
-
   @override
   bool visitNullLiteral(NullLiteral node) => visitNode(node);
 

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

@@ -1440,24 +1440,6 @@ class ConstantVisitor extends UnifyingAstVisitor<Constant> {
               }
               list.addAll(listValue);
           }
-        case NullAwareElement():
-          var value = evaluateConstant(element.value);
-          switch (value) {
-            case InvalidConstant():
-              return value;
-            case DartObjectImpl():
-              if (value.isNull) {
-                continue;
-              }
-              var result = _buildListConstant(
-                list,
-                [element.value],
-                typeSystem,
-                listType,
-                elementType,
-              );
-              return result;
-          }
       }
     }
 
@@ -1548,11 +1530,6 @@ class ConstantVisitor extends UnifyingAstVisitor<Constant> {
               }
               map.addAll(mapValue);
           }
-        case NullAwareElement():
-          // TODO(cstefantsova): Should it rather be its own code, for example,
-          // `CompileTimeErrorCode.NULL_AWARE_ELEMENT_IN_MAP`?
-          return InvalidConstant.forEntity(
-              element, CompileTimeErrorCode.EXPRESSION_IN_MAP);
       }
     }
 
@@ -1630,19 +1607,6 @@ class ConstantVisitor extends UnifyingAstVisitor<Constant> {
               }
               set.addAll(setValue);
           }
-        case NullAwareElement():
-          var value = evaluateConstant(element.value);
-          switch (value) {
-            case InvalidConstant():
-              return value;
-            case DartObjectImpl():
-              if (value.isNull) {
-                continue;
-              }
-              var result =
-                  _buildSetConstant(set, [element.value], typeSystem, setType);
-              return result;
-          }
       }
     }
 

pkg/analyzer/lib/src/fasta/ast_builder.dart

@@ -4829,24 +4829,21 @@ class AstBuilder extends StackListener {
     assert(optional(':', colon));
     debugEvent("LiteralMapEntry");
 
+    // TODO(cstefantsova): Handle null-aware map entries.
     if (!enableNullAwareElements &&
         (nullAwareKeyToken != null || nullAwareValueToken != null)) {
       _reportFeatureNotEnabled(
         feature: ExperimentalFeatures.null_aware_elements,
         startToken: nullAwareKeyToken ?? nullAwareValueToken!,
       );
-      nullAwareKeyToken = null;
-      nullAwareValueToken = null;
     }
 
     var value = pop() as ExpressionImpl;
     var key = pop() as ExpressionImpl;
     push(
       MapLiteralEntryImpl(
-        keyQuestion: nullAwareKeyToken,
         key: key,
         separator: colon,
-        valueQuestion: nullAwareValueToken,
         value: value,
       ),
     );
@@ -5142,19 +5139,12 @@ class AstBuilder extends StackListener {
   @override
   void handleNullAwareElement(Token nullAwareElement) {
     debugEvent('NullAwareElement');
+    // TODO(cstefantsova): Handle null-aware elements.
     if (!enableNullAwareElements) {
       _reportFeatureNotEnabled(
         feature: ExperimentalFeatures.null_aware_elements,
         startToken: nullAwareElement,
       );
-    } else {
-      var expression = pop() as ExpressionImpl;
-      push(
-        NullAwareElementImpl(
-          question: nullAwareElement,
-          value: expression,
-        ),
-      );
     }
   }
 

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

@@ -3249,21 +3249,6 @@ class ResolverVisitor extends ThrowingAstVisitor<void>
     return imposedType ?? typeProvider.dynamicType;
   }
 
-  @override
-  void visitNullAwareElement(NullAwareElement node,
-      {CollectionLiteralContext? context}) {
-    inferenceLogWriter?.enterElement(node);
-
-    var elementType = context?.elementType;
-    if (elementType != null) {
-      elementType = typeSystem.makeNullable(elementType);
-    }
-
-    analyzeExpression(node.value, elementType ?? UnknownInferredType.instance);
-
-    inferenceLogWriter?.exitElement(node);
-  }
-
   @override
   void visitNullLiteral(NullLiteral node,
       {DartType contextType = UnknownInferredType.instance}) {