Don't include extended type into syntactic scope of extensions.

R=brianwilkerson@google.com

Change-Id: I794dbdcef97652d7a7f17421f733f21d2f157de4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/112493
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

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

@@ -5382,13 +5382,6 @@ abstract class ScopedVisitor extends UnifyingAstVisitor<void> {
           enclosingExtension = extensionElement;
           nameScope = new TypeParameterScope(nameScope, extensionElement);
           visitExtensionDeclarationInScope(node);
-          DartType extendedType = extensionElement.extendedType;
-          if (extendedType is InterfaceType) {
-            nameScope = new ClassScope(nameScope, extendedType.element);
-          } else if (extendedType is FunctionType) {
-            nameScope =
-                new ClassScope(nameScope, typeProvider.functionType.element);
-          }
           nameScope = ExtensionScope(nameScope, extensionElement);
           visitExtensionMembersInScope(node);
         } finally {

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

@@ -1490,4 +1490,116 @@ extension E on C {
     assertElement(identifier, findElement.method('a'));
     assertType(identifier, 'void Function(int)');
   }
+
+  test_topLevel_function_fromInstance() async {
+    await assertNoErrorsInCode('''
+class C {
+  void a() {}
+}
+
+void a() {}
+
+extension E on C {
+  void b() {
+    a();
+  }
+}
+''');
+    var invocation = findNode.methodInvocation('a();');
+    assertElement(invocation, findElement.topFunction('a'));
+    assertInvokeType(invocation, 'void Function()');
+  }
+
+  test_topLevel_function_fromStatic() async {
+    await assertNoErrorsInCode('''
+class C {
+  void a() {}
+}
+
+void a() {}
+
+extension E on C {
+  static void b() {
+    a();
+  }
+}
+''');
+    var invocation = findNode.methodInvocation('a();');
+    assertElement(invocation, findElement.topFunction('a'));
+    assertInvokeType(invocation, 'void Function()');
+  }
+
+  test_topLevel_getter_fromInstance() async {
+    await assertNoErrorsInCode('''
+class C {
+  int get a => 0;
+}
+
+int get a => 0;
+
+extension E on C {
+  void b() {
+    a;
+  }
+}
+''');
+    var identifier = findNode.simple('a;');
+    assertElement(identifier, findElement.topGet('a'));
+    assertType(identifier, 'int');
+  }
+
+  test_topLevel_getter_fromStatic() async {
+    await assertNoErrorsInCode('''
+class C {
+  int get a => 0;
+}
+
+int get a => 0;
+
+extension E on C {
+  static void b() {
+    a;
+  }
+}
+''');
+    var identifier = findNode.simple('a;');
+    assertElement(identifier, findElement.topGet('a'));
+    assertType(identifier, 'int');
+  }
+
+  test_topLevel_setter_fromInstance() async {
+    await assertNoErrorsInCode('''
+class C {
+  set a(int _) {}
+}
+
+set a(int _) {}
+
+extension E on C {
+  void b() {
+    a = 0;
+  }
+}
+''');
+    var identifier = findNode.simple('a = 0;');
+    assertElement(identifier, findElement.topSet('a'));
+  }
+
+  test_topLevel_setter_fromStatic() async {
+    await assertNoErrorsInCode('''
+class C {
+  set a(int _) {}
+}
+
+set a(int _) {}
+
+extension E on C {
+  static void b() {
+    a = 0;
+  }
+}
+''');
+    var identifier = findNode.simple('a = 0;');
+    assertElement(identifier, findElement.topSet('a'));
+  }
 }