Element model support for covariant

pkg/analyzer/lib/src/summary/link.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * This library is capable of producing linked summaries from unlinked
  * ones (or prelinked ones).  It functions by building a miniature
  * element model to represent the contents of the summaries, and then
  * scanning the element model to gather linked information and adding
  * it to the summary data structures.
@@ skipping 3841 matching lines @@
   @override
   bool get inheritsCovariant => _inheritsCovariant;
 
   @override
   void set inheritsCovariant(bool value) {
     _inheritsCovariant = value;
   }
 
   @override
   bool get isCovariant {
-    if (inheritsCovariant) {
+    if (isExplicitlyCovariant || inheritsCovariant) {
       return true;
     }
     for (UnlinkedExpr annotation in _unlinkedParam.annotations) {
       if (annotation.operations.length == 1 &&
           annotation.operations[0] == UnlinkedExprOperation.pushReference) {
         ReferenceableElementForLink element =
             this.compilationUnit.resolveRef(annotation.references[0].reference);
         if (element is PropertyAccessorElementForLink &&
             element.name == 'checked' &&
             element.library.name == 'meta') {
           return true;
         }
       }
     }
     return false;
   }
 
   @override
+  bool get isExplicitlyCovariant => _unlinkedParam.isExplicitlyCovariant;
+
+  @override
   String get name => _unlinkedParam.name;
 
   @override
   ParameterKind get parameterKind {
     switch (_unlinkedParam.kind) {
       case UnlinkedParamKind.required:
         return ParameterKind.REQUIRED;
       case UnlinkedParamKind.positional:
         return ParameterKind.POSITIONAL;
       case UnlinkedParamKind.named:
@@ skipping 57 matching lines @@
 class ParameterElementForLink_VariableSetter implements ParameterElementImpl {
   @override
   final PropertyAccessorElementForLink_Variable enclosingElement;
 
   @override
   bool inheritsCovariant = false;
 
   ParameterElementForLink_VariableSetter(this.enclosingElement);
 
   @override
-  bool get isCovariant => false;
+  bool get isCovariant => isExplicitlyCovariant || inheritsCovariant;
+
+  @override
+  bool get isExplicitlyCovariant => enclosingElement.variable.isCovariant;
 
   @override
   bool get isSynthetic => true;
 
   @override
   String get name => 'x';
 
   @override
   ParameterKind get parameterKind => ParameterKind.REQUIRED;
 
@@ skipping 933 matching lines @@
     if (unlinkedVariable.initializer == null) {
       return null;
     } else {
       return _initializer ??= new FunctionElementForLink_Initializer(this);
     }
   }
 
   @override
   bool get isConst => unlinkedVariable.isConst;
 
+  /**
+   * Return `true` if this variable is a field that was explicitly marked as
+   * being covariant (in the setter's parameter).
+   */
+  bool get isCovariant => unlinkedVariable.isCovariant;
+
   @override
   bool get isFinal => unlinkedVariable.isFinal;
 
   @override
   bool get isStatic;
 
   @override
   bool get isSynthetic => false;
 
   @override
@@ skipping 27 matching lines @@
    * there are no type parameters in scope.
    */
   TypeParameterizedElementMixin get _typeParameterContext;
 
   @override
   noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 
   @override
   String toString() => '$enclosingElement.$name';
 }