Resolve rest elements in list patterns.

Change-Id: I95c210bde168b09c86a7a42ff984b5728440f7a9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/271741
Reviewed-by: Samuel Rawlins <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

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

@@ -10967,14 +10967,21 @@ class RestPatternElementImpl extends AstNodeImpl
   RestPatternElementImpl({
     required this.operator,
     required this.pattern,
-  });
+  }) {
+    _becomeParentOf(pattern);
+  }
 
   @override
   Token get beginToken => operator;
 
   @override
   Token get endToken => pattern?.endToken ?? operator;
 
+  @override
+  ChildEntities get _childEntities => ChildEntities()
+    ..addToken('operator', operator)
+    ..addNode('pattern', pattern);
+
   @override
   E? accept<E>(AstVisitor<E> visitor) {
     return visitor.visitRestPatternElement(this);

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

@@ -911,9 +911,10 @@ class ResolverVisitor extends ThrowingAstVisitor<void>
   }
 
   @override
-  DartPattern? getRestPatternElementPattern(covariant DartPatternImpl node) {
-    // TODO(scheglov): implement getRestPatternElementPattern
-    throw UnimplementedError();
+  DartPattern? getRestPatternElementPattern(
+    covariant RestPatternElementImpl element,
+  ) {
+    return element.pattern;
   }
 
   @override
@@ -1038,11 +1039,8 @@ class ResolverVisitor extends ThrowingAstVisitor<void>
   @override
   void handleListPatternRestElement(
     DartPattern container,
-    covariant DartPattern restElement,
-  ) {
-    // TODO(scheglov): implement handleListPatternRestElement
-    throw UnimplementedError();
-  }
+    covariant RestPatternElementImpl restElement,
+  ) {}
 
   @override
   void handleMapPatternEntry(DartPattern container, AstNode entryElement) {
@@ -1145,9 +1143,8 @@ class ResolverVisitor extends ThrowingAstVisitor<void>
   }
 
   @override
-  bool isRestPatternElement(covariant DartPatternImpl node) {
-    // TODO(scheglov): implement isRestPatternElement
-    return false;
+  bool isRestPatternElement(AstNode node) {
+    return node is RestPatternElementImpl;
   }
 
   @override

pkg/analyzer/test/generated/patterns_parser_test.dart

@@ -6706,6 +6706,7 @@ ListPattern
   leftBracket: [
   elements
     RestPatternElement
+      operator: ...
   rightBracket: ]
 ''');
   }
@@ -6725,6 +6726,10 @@ ListPattern
   leftBracket: [
   elements
     RestPatternElement
+      operator: ...
+      pattern: VariablePattern
+        keyword: var
+        name: y
   rightBracket: ]
 ''');
   }

pkg/analyzer/test/src/dart/resolution/list_pattern_test.dart

@@ -101,6 +101,33 @@ ListPattern
 ''');
   }
 
+  test_matchList_noTypeArguments_restElement() async {
+    await assertNoErrorsInCode(r'''
+void f(List<int> x) {
+  if (x case [0, ...var rest]) {}
+}
+''');
+    final node = findNode.singleGuardedPattern.pattern;
+    assertResolvedNodeText(node, r'''
+ListPattern
+  leftBracket: [
+  elements
+    ConstantPattern
+      expression: IntegerLiteral
+        literal: 0
+        staticType: int
+    RestPatternElement
+      operator: ...
+      pattern: VariablePattern
+        keyword: var
+        name: rest
+        declaredElement: hasImplicitType rest@46
+          type: List<int>
+  rightBracket: ]
+  requiredType: List<int>
+''');
+  }
+
   test_matchList_noTypeArguments_variable_untyped() async {
     await assertNoErrorsInCode(r'''
 void f(List<int> x) {