Remove the analyzer's AST representation for PatternAssignmentStatement.

There's no such node in the grammar.  Pattern assignment statements
are simply expression statements whose expression is a
PatternAssignment (in the same way that a statement like `a = b;` is
an expression statement whose expression is `a = b`).

Change-Id: I09ea7deade3eb942f5ae464f72f3e217c164594e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/272384
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

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

@@ -567,8 +567,6 @@ abstract class AstVisitor<R> {
 
   R? visitPatternAssignment(PatternAssignment node);
 
-  R? visitPatternAssignmentStatement(PatternAssignmentStatement node);
-
   R? visitPatternVariableDeclaration(PatternVariableDeclaration node);
 
   R? visitPatternVariableDeclarationStatement(
@@ -4113,20 +4111,6 @@ abstract class PatternAssignment implements Expression {
   DartPattern get pattern;
 }
 
-/// A pattern assignment used as a statement.
-///
-///    patternAssignmentStatement ::=
-///        [PatternAssignment] ';'
-///
-/// Clients may not extend, implement or mix-in this class.
-abstract class PatternAssignmentStatement implements Statement {
-  /// Return the pattern assignment that comprises the statement.
-  PatternAssignment get assignment;
-
-  /// Return the semicolon terminating the statement.
-  Token get semicolon;
-}
-
 /// A pattern variable declaration.
 ///
 ///    patternDeclaration ::=

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

@@ -545,10 +545,6 @@ class GeneralizingAstVisitor<R> implements AstVisitor<R> {
   @override
   R? visitPatternAssignment(PatternAssignment node) => visitExpression(node);
 
-  @override
-  R? visitPatternAssignmentStatement(PatternAssignmentStatement node) =>
-      visitStatement(node);
-
   @override
   R? visitPatternVariableDeclaration(PatternVariableDeclaration node) =>
       visitNode(node);
@@ -1415,12 +1411,6 @@ class RecursiveAstVisitor<R> implements AstVisitor<R> {
     return null;
   }
 
-  @override
-  R? visitPatternAssignmentStatement(PatternAssignmentStatement node) {
-    node.visitChildren(this);
-    return null;
-  }
-
   @override
   R? visitPatternVariableDeclaration(PatternVariableDeclaration node) {
     node.visitChildren(this);
@@ -2089,9 +2079,6 @@ class SimpleAstVisitor<R> implements AstVisitor<R> {
   @override
   R? visitPatternAssignment(PatternAssignment node) => null;
 
-  @override
-  R? visitPatternAssignmentStatement(PatternAssignmentStatement node) => null;
-
   @override
   R? visitPatternVariableDeclaration(PatternVariableDeclaration node) => null;
 
@@ -2611,10 +2598,6 @@ class ThrowingAstVisitor<R> implements AstVisitor<R> {
   @override
   R? visitPatternAssignment(PatternAssignment node) => _throw(node);
 
-  @override
-  R? visitPatternAssignmentStatement(PatternAssignmentStatement node) =>
-      _throw(node);
-
   @override
   R? visitPatternVariableDeclaration(PatternVariableDeclaration node) =>
       _throw(node);
@@ -3674,14 +3657,6 @@ class TimedAstVisitor<T> implements AstVisitor<T> {
     return result;
   }
 
-  @override
-  T? visitPatternAssignmentStatement(PatternAssignmentStatement node) {
-    stopwatch.start();
-    T? result = _baseVisitor.visitPatternAssignmentStatement(node);
-    stopwatch.stop();
-    return result;
-  }
-
   @override
   T? visitPatternVariableDeclaration(PatternVariableDeclaration node) {
     stopwatch.start();
@@ -4482,10 +4457,6 @@ class UnifyingAstVisitor<R> implements AstVisitor<R> {
   @override
   R? visitPatternAssignment(PatternAssignment node) => visitNode(node);
 
-  @override
-  R? visitPatternAssignmentStatement(PatternAssignmentStatement node) =>
-      visitNode(node);
-
   @override
   R? visitPatternVariableDeclaration(PatternVariableDeclaration node) =>
       visitNode(node);

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

@@ -9893,46 +9893,6 @@ class PatternAssignmentImpl extends ExpressionImpl
   }
 }
 
-/// A pattern assignment used as a statement.
-///
-///    patternAssignmentStatement ::=
-///        [PatternAssignment] ';'
-class PatternAssignmentStatementImpl extends StatementImpl
-    implements PatternAssignmentStatement {
-  @override
-  final PatternAssignmentImpl assignment;
-
-  @override
-  final Token semicolon;
-
-  PatternAssignmentStatementImpl({
-    required this.assignment,
-    required this.semicolon,
-  }) {
-    _becomeParentOf(assignment);
-  }
-
-  @override
-  Token get beginToken => assignment.beginToken;
-
-  @override
-  Token get endToken => semicolon;
-
-  @override
-  ChildEntities get _childEntities => super._childEntities
-    ..addNode('assignment', assignment)
-    ..addToken('semicolon', semicolon);
-
-  @override
-  E? accept<E>(AstVisitor<E> visitor) =>
-      visitor.visitPatternAssignmentStatement(this);
-
-  @override
-  void visitChildren(AstVisitor visitor) {
-    assignment.accept(visitor);
-  }
-}
-
 /// A pattern variable declaration.
 ///
 ///    patternDeclaration ::=

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

@@ -952,12 +952,6 @@ class ToSourceVisitor implements AstVisitor<void> {
     _visitNode(node.expression);
   }
 
-  @override
-  void visitPatternAssignmentStatement(PatternAssignmentStatement node) {
-    _visitNode(node.assignment);
-    sink.write(';');
-  }
-
   @override
   void visitPatternVariableDeclaration(PatternVariableDeclaration node) {
     _visitNodeList(node.metadata, separator: ' ', suffix: ' ');

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

@@ -1099,13 +1099,6 @@ class AstComparator implements AstVisitor<bool> {
         isEqualNodes(node.expression, other.expression);
   }
 
-  @override
-  bool visitPatternAssignmentStatement(PatternAssignmentStatement node) {
-    var other = _other as PatternAssignmentStatement;
-    return isEqualNodes(node.assignment, other.assignment) &&
-        isEqualTokens(node.semicolon, other.semicolon);
-  }
-
   @override
   bool visitPatternVariableDeclaration(PatternVariableDeclaration node) {
     var other = _other as PatternVariableDeclaration;

pkg/analyzer/lib/src/lint/linter_visitor.dart

@@ -671,12 +671,6 @@ class LinterVisitor implements AstVisitor<void> {
     node.visitChildren(this);
   }
 
-  @override
-  void visitPatternAssignmentStatement(PatternAssignmentStatement node) {
-    _runSubscriptions(node, registry._forPatternAssignmentStatement);
-    node.visitChildren(this);
-  }
-
   @override
   void visitPatternVariableDeclaration(PatternVariableDeclaration node) {
     _runSubscriptions(node, registry._forPatternVariableDeclaration);
@@ -1157,8 +1151,6 @@ class NodeLintRegistry {
   final List<_Subscription<PartDirective>> _forPartDirective = [];
   final List<_Subscription<PartOfDirective>> _forPartOfDirective = [];
   final List<_Subscription<PatternAssignment>> _forPatternAssignment = [];
-  final List<_Subscription<PatternAssignmentStatement>>
-      _forPatternAssignmentStatement = [];
   final List<_Subscription<PatternVariableDeclaration>>
       _forPatternVariableDeclaration = [];
   final List<_Subscription<PatternVariableDeclarationStatement>>
@@ -1708,11 +1700,6 @@ class NodeLintRegistry {
         .add(_Subscription(linter, visitor, _getTimer(linter)));
   }
 
-  void addPatternAssignmentStatement(LintRule linter, AstVisitor visitor) {
-    _forPatternAssignmentStatement
-        .add(_Subscription(linter, visitor, _getTimer(linter)));
-  }
-
   void addPatternVariableDeclaration(LintRule linter, AstVisitor visitor) {
     _forPatternVariableDeclaration
         .add(_Subscription(linter, visitor, _getTimer(linter)));

pkg/analyzer/lib/src/test_utilities/find_node.dart

@@ -521,10 +521,6 @@ class FindNode {
     return _node(search, (n) => n is PatternAssignment);
   }
 
-  PatternAssignmentStatement patternAssignmentStatement(String search) {
-    return _node(search, (n) => n is PatternAssignmentStatement);
-  }
-
   PatternVariableDeclaration patternVariableDeclaration(String search) {
     return _node(search, (n) => n is PatternVariableDeclaration);
   }