Version 2.19.0-413.0.dev

Merge ae1ed9e into dev

DEPS

@@ -51,7 +51,7 @@ vars = {
 
   # co19 is a cipd package. Use update.sh in tests/co19[_2] to update these
   # hashes.
-  "co19_rev": "19439c0d58a0df422c4acc4ae97a3deeb98d0f67",
+  "co19_rev": "2a9309cd36effe3b083df6a2761fea6b7213c670",
   # This line prevents conflicts when both packages are rolled simultaneously.
   "co19_2_rev": "cdab7e4e26f3dd534bcb297ff3f9e9aa5c7a04fb",
 

pkg/_fe_analyzer_shared/lib/src/type_inference/type_analyzer.dart

@@ -551,20 +551,33 @@ mixin TypeAnalyzer<
       Pattern node,
       {Type? elementType,
       required List<Node> elements}) {
-    // Stack: ()
-    Type? matchedElementType = typeOperations.matchListType(matchedType);
-    if (matchedElementType == null) {
-      if (typeOperations.isDynamic(matchedType)) {
-        matchedElementType = dynamicType;
+    Type valueType;
+    if (elementType != null) {
+      valueType = elementType;
+    } else {
+      Type? listElementType = typeOperations.matchListType(matchedType);
+      if (listElementType != null) {
+        valueType = listElementType;
+      } else if (typeOperations.isDynamic(matchedType)) {
+        valueType = dynamicType;
       } else {
-        matchedElementType = objectQuestionType;
+        valueType = objectQuestionType;
       }
     }
+    // Stack: ()
     for (Node element in elements) {
-      dispatchPattern(matchedElementType, context, element);
+      if (isRestPatternElement(element)) {
+        Pattern? subPattern = getRestPatternElementPattern(element);
+        if (subPattern != null) {
+          dispatchPattern(listType(valueType), context, subPattern);
+        }
+        handleRestPatternElement(node, element);
+      } else {
+        dispatchPattern(valueType, context, element);
+      }
     }
     // Stack: (n * Pattern) where n = elements.length
-    Type requiredType = listType(elementType ?? matchedElementType);
+    Type requiredType = listType(valueType);
     Node? irrefutableContext = context.irrefutableContext;
     if (irrefutableContext != null &&
         !typeOperations.isAssignableTo(matchedType, requiredType)) {
@@ -582,19 +595,40 @@ mixin TypeAnalyzer<
   /// subpatterns.
   ///
   /// Stack effect: none.
-  Type analyzeListPatternSchema(
-      {Type? elementType, required List<Node> elements}) {
-    if (elementType == null) {
-      if (elements.isEmpty) {
-        return objectQuestionType;
+  Type analyzeListPatternSchema({
+    required Type? elementType,
+    required List<Node> elements,
+  }) {
+    if (elementType != null) {
+      return listType(elementType);
+    }
+
+    if (elements.isEmpty) {
+      return listType(unknownType);
+    }
+
+    Type? currentGLB;
+    for (Node element in elements) {
+      Type? typeToAdd;
+      if (isRestPatternElement(element)) {
+        Pattern? subPattern = getRestPatternElementPattern(element);
+        if (subPattern != null) {
+          Type subPatternType = dispatchPatternSchema(subPattern);
+          typeToAdd = typeOperations.matchIterableType(subPatternType);
+        }
+      } else {
+        typeToAdd = dispatchPatternSchema(element);
       }
-      elementType = dispatchPatternSchema(elements[0]);
-      for (int i = 1; i < elements.length; i++) {
-        elementType = typeOperations.glb(
-            elementType!, dispatchPatternSchema(elements[i]));
+      if (typeToAdd != null) {
+        if (currentGLB == null) {
+          currentGLB = typeToAdd;
+        } else {
+          currentGLB = typeOperations.glb(currentGLB, typeToAdd);
+        }
       }
     }
-    return listType(elementType!);
+    currentGLB ??= unknownType;
+    return listType(currentGLB);
   }
 
   /// Analyzes a logical-or or logical-and pattern.  [node] is the pattern
@@ -1213,6 +1247,9 @@ mixin TypeAnalyzer<
 
   List<Variable>? getJoinedVariableComponents(Variable variable);
 
+  /// If [node] is [isRestPatternElement], returns its optional pattern.
+  Pattern? getRestPatternElementPattern(Node node);
+
   /// Returns an [ExpressionCaseInfo] object describing the [index]th `case` or
   /// `default` clause in the switch expression [node].
   ///
@@ -1331,6 +1368,11 @@ mixin TypeAnalyzer<
   /// Stack effect: pushes (Statement).
   void handleNoStatement(Statement node);
 
+  /// Called after visiting a rest element in a list or map pattern.
+  ///
+  /// Stack effect: pushes (Pattern).
+  void handleRestPatternElement(Pattern container, Node restElement);
+
   /// Called after visiting the scrutinee part of a switch statement or switch
   /// expression.  This is a hook to allow the client to start exhaustiveness
   /// analysis.
@@ -1343,6 +1385,9 @@ mixin TypeAnalyzer<
   /// Stack effect: none.
   void handleSwitchScrutinee(Type type);
 
+  /// Returns whether [node] is a rest element in a list or map pattern.
+  bool isRestPatternElement(Node node);
+
   /// Queries whether the switch statement or expression represented by [node]
   /// was exhaustive.  [expressionType] is the static type of the scrutinee.
   ///

pkg/_fe_analyzer_shared/lib/src/type_inference/type_operations.dart

@@ -75,6 +75,10 @@ mixin TypeOperations<Type extends Object> {
   /// of [type] and `Null`.
   Type makeNullable(Type type);
 
+  /// If [type] is a subtype of the type `Iterable<T>` for some `T`, returns
+  /// the type `T`.  Otherwise returns `null`.
+  Type? matchIterableType(Type type);
+
   /// If [type] is a subtype of the type `List<T>` for some `T`, returns the
   /// type `T`.  Otherwise returns `null`.
   Type? matchListType(Type type);

pkg/_fe_analyzer_shared/test/mini_ast.dart

@@ -247,10 +247,13 @@ Expression intLiteral(int value, {bool? expectConversionToDouble}) =>
         expectConversionToDouble: expectConversionToDouble,
         location: computeLocation());
 
-Pattern listPattern(List<Pattern> elements, {String? elementType}) =>
+Pattern listPattern(List<ListPatternElement> elements, {String? elementType}) =>
     _ListPattern(elementType == null ? null : Type(elementType), elements,
         location: computeLocation());
 
+ListPatternElement listPatternRestElement([Pattern? pattern]) =>
+    _RestPatternElement(pattern, location: computeLocation());
+
 Statement localFunction(List<Statement> body) {
   var location = computeLocation();
   return _LocalFunction(_Block(body, location: location), location: location);
@@ -685,6 +688,12 @@ class Label extends Node {
   String toString() => _name;
 }
 
+abstract class ListPatternElement implements Node {
+  void preVisit(PreVisitor visitor, VariableBinder<Node, Var> variableBinder);
+
+  String _debugString({required bool needsKeywordOrType});
+}
+
 /// Representation of an expression that can appear on the left hand side of an
 /// assignment (or as the target of `++` or `--`).  Methods in this class may be
 /// used to create more complex expressions based on this one.
@@ -775,7 +784,13 @@ class MiniAstOperations
     'List <: int': false,
     'List <: Iterable': true,
     'List <: Object': true,
+    'List<dynamic> <: Object': true,
+    'List<Object?> <: Object': true,
+    'List<int> <: dynamic': true,
+    'List<int> <: Iterable<double>': false,
+    'List<int> <: Iterable<int>': true,
     'List<int> <: List<num>': true,
+    'List<int> <: String': false,
     'Never <: int': true,
     'Never <: int?': true,
     'Never <: Null': true,
@@ -847,6 +862,8 @@ class MiniAstOperations
   };
 
   static final Map<String, Type> _coreGlbs = {
+    'Object?, double': Type('double'),
+    'Object?, int': Type('int'),
     'double, int': Type('Never'),
     'double?, int?': Type('Null'),
     'int?, num': Type('int'),
@@ -1029,12 +1046,22 @@ class MiniAstOperations
   @override
   Type makeNullable(Type type) => lub(type, Type('Null'));
 
+  @override
+  Type? matchIterableType(Type type) {
+    if (type is NonFunctionType &&
+        type.name == 'Iterable' &&
+        type.args.length == 1) {
+      return type.args[0];
+    }
+    return null;
+  }
+
   @override
   Type? matchListType(Type type) {
-    if (type is NonFunctionType) {
-      if (type.args.length == 1) {
-        return type.args[0];
-      }
+    if (type is NonFunctionType &&
+        type.name == 'List' &&
+        type.args.length == 1) {
+      return type.args[0];
     }
     return null;
   }
@@ -1151,7 +1178,9 @@ class ObjectPatternRequiredType {
   }
 }
 
-abstract class Pattern extends Node with PossiblyGuardedPattern {
+abstract class Pattern extends Node
+    with PossiblyGuardedPattern
+    implements ListPatternElement {
   Pattern._({required super.location}) : super._();
 
   Pattern get nullAssert =>
@@ -1180,8 +1209,6 @@ abstract class Pattern extends Node with PossiblyGuardedPattern {
   Pattern or(Pattern other) =>
       _LogicalPattern(this, other, isAnd: false, location: computeLocation());
 
-  void preVisit(PreVisitor visitor, VariableBinder<Node, Var> variableBinder);
-
   RecordPatternField recordField([String? name]) {
     return RecordPatternField(
       name: name,
@@ -1206,8 +1233,6 @@ abstract class Pattern extends Node with PossiblyGuardedPattern {
       location: location,
     );
   }
-
-  String _debugString({required bool needsKeywordOrType});
 }
 
 class PatternVariableJoin extends Var {
@@ -2554,7 +2579,7 @@ class _LabeledStatement extends Statement {
 class _ListPattern extends Pattern {
   final Type? _elementType;
 
-  final List<Pattern> _elements;
+  final List<ListPatternElement> _elements;
 
   _ListPattern(this._elementType, this._elements, {required super.location})
       : super._();
@@ -3256,6 +3281,11 @@ class _MiniAstTypeAnalyzer
     return null;
   }
 
+  @override
+  Pattern? getRestPatternElementPattern(Node element) {
+    return element is _RestPatternElement ? element._pattern : null;
+  }
+
   @override
   SwitchExpressionMemberInfo<Node, Expression, Var>
       getSwitchExpressionMemberInfo(
@@ -3400,6 +3430,19 @@ class _MiniAstTypeAnalyzer
     _irBuilder.atom('noop', Kind.statement, location: node.location);
   }
 
+  @override
+  void handleRestPatternElement(
+    Pattern container,
+    covariant _RestPatternElement restElement,
+  ) {
+    if (restElement._pattern != null) {
+      _irBuilder.apply('...', [Kind.pattern], Kind.pattern,
+          location: restElement.location);
+    } else {
+      _irBuilder.atom('...', Kind.pattern, location: restElement.location);
+    }
+  }
+
   @override
   void handleSwitchScrutinee(Type type) {}
 
@@ -3418,6 +3461,11 @@ class _MiniAstTypeAnalyzer
     }
   }
 
+  @override
+  bool isRestPatternElement(Node element) {
+    return element is _RestPatternElement;
+  }
+
   @override
   bool isSwitchExhaustive(
       covariant _SwitchStatement node, Type expressionType) {
@@ -3852,6 +3900,27 @@ class _RelationalPattern extends Pattern {
   _debugString({required bool needsKeywordOrType}) => '$operator $operand';
 }
 
+class _RestPatternElement extends Node implements ListPatternElement {
+  final Pattern? _pattern;
+
+  _RestPatternElement(this._pattern, {required super.location}) : super._();
+
+  @override
+  void preVisit(PreVisitor visitor, VariableBinder<Node, Var> variableBinder) {
+    _pattern?.preVisit(visitor, variableBinder);
+  }
+
+  @override
+  String _debugString({required bool needsKeywordOrType}) {
+    var pattern = _pattern;
+    if (pattern == null) {
+      return '...';
+    } else {
+      return '...${pattern._debugString(needsKeywordOrType: false)}';
+    }
+  }
+}
+
 class _Return extends Statement {
   _Return({required super.location});