Report COULD_NOT_INFER when inference fails for ExtensionOverride.

scheglov · commit-bot@chromium.org · commit f444374bb752 · 2019-08-12T20:28:15.000Z
R=brianwilkerson@google.com Change-Id: Ibadc5deac6289216b3d1547b963a206560c64691 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/112760 Reviewed-by: Brian Wilkerson <brianwilkerson@google.com> Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
diff --git a/pkg/analyzer/lib/src/dart/resolver/extension_member_resolver.dart b/pkg/analyzer/lib/src/dart/resolver/extension_member_resolver.dart
@@ -93,11 +93,7 @@ class ExtensionMemberResolver {
     var receiverExpression = arguments[0];
     var receiverType = receiverExpression.staticType;
 
-    var typeArgumentTypes = _inferTypeArguments(
-      element,
-      receiverType,
-      node.typeArguments,
-    );
+    var typeArgumentTypes = _inferTypeArguments(node, receiverType);
 
     nodeImpl.typeArgumentTypes = typeArgumentTypes;
     nodeImpl.extendedType = Substitution.fromPairs(
@@ -307,23 +303,24 @@ class ExtensionMemberResolver {
     return candidates;
   }
 
-  /// Given the generic [extension] element, either return types specified
+  /// Given the generic [element] element, either return types specified
   /// explicitly in [typeArguments], or infer type arguments from the given
   /// [receiverType].
   ///
   /// If the number of explicit type arguments is different than the number
   /// of extension's type parameters, or inference fails, return `dynamic`
   /// for all type parameters.
   List<DartType> _inferTypeArguments(
-    ExtensionElement extension,
+    ExtensionOverride node,
     DartType receiverType,
-    TypeArgumentList typeArguments,
   ) {
-    var typeParameters = extension.typeParameters;
+    var element = node.staticElement;
+    var typeParameters = element.typeParameters;
     if (typeParameters.isEmpty) {
       return const <DartType>[];
     }
 
+    var typeArguments = node.typeArguments;
     if (typeArguments != null) {
       var arguments = typeArguments.arguments;
       if (arguments.length == typeParameters.length) {
@@ -340,10 +337,14 @@ class ExtensionMemberResolver {
       );
       inferrer.constrainArgument(
         receiverType,
-        extension.extendedType,
+        element.extendedType,
         'extendedType',
       );
-      return inferrer.infer(typeParameters);
+      return inferrer.infer(
+        typeParameters,
+        errorReporter: _errorReporter,
+        errorNode: node.extensionName,
+      );
     }
   }
 
diff --git a/pkg/analyzer/test/src/dart/resolution/type_inference/extension_methods_test.dart b/pkg/analyzer/test/src/dart/resolution/type_inference/extension_methods_test.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/analysis/features.dart';
+import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -283,6 +284,23 @@ void f(A<int> a) {
     );
   }
 
+  test_override_inferTypeArguments_error_couldNotInfer() async {
+    await assertErrorsInCode('''
+extension E<T extends num> on T {
+  void foo() {}
+}
+
+f(String s) {
+  E(s).foo();
+}
+''', [
+      error(StrongModeCode.COULD_NOT_INFER, 69, 1),
+    ]);
+    var override = findNode.extensionOverride('E(s)');
+    assertElementTypeStrings(override.typeArgumentTypes, ['String']);
+    assertElementTypeString(override.extendedType, 'String');
+  }
+
   test_override_inferTypeArguments_getter() async {
     await assertNoErrorsInCode('''
 class A<T> {}
