fix #25171, clear "hasBeenInferred" flag when re-running resolution

pkg/analyzer/test/src/task/dart_test.dart

 // Copyright (c) 2015, 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.
 
 library analyzer.test.src.task.dart_test;
 
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/element.dart';
@@ skipping 1409 matching lines @@
 library my_lib1;
 ''');
     computeResult(lib1Target, LIBRARY_CYCLE);
     expect(outputs[LIBRARY_CYCLE], hasLength(1));
     computeResult(lib2Target, LIBRARY_CYCLE);
     expect(outputs[LIBRARY_CYCLE], hasLength(1));
     computeResult(lib3Target, LIBRARY_CYCLE);
     expect(outputs[LIBRARY_CYCLE], hasLength(1));
   }
 
+  void test_library_cycle_override_inference_incremental() {
+    enableStrongMode();
+    Source lib1Source = newSource(
+        '/my_lib1.dart',
+        '''
+library my_lib1;
+import 'my_lib3.dart';
+''');
+    Source lib2Source = newSource(
+        '/my_lib2.dart',
+        '''
+library my_lib2;
+import 'my_lib1.dart';
+''');
+    Source lib3Source = newSource(
+        '/my_lib3.dart',
+        '''
+library my_lib3;
+import 'my_lib2.dart';
+
+class A {
+  int foo(int x) => null;
+}
+class B extends A {
+  foo(x) => null;
+}
+''');
+    AnalysisTarget lib1Target = new LibrarySpecificUnit(lib1Source, lib1Source);
+    AnalysisTarget lib2Target = new LibrarySpecificUnit(lib2Source, lib2Source);
+    AnalysisTarget lib3Target = new LibrarySpecificUnit(lib3Source, lib3Source);
+
+    computeResult(lib1Target, RESOLVED_UNIT);
+    computeResult(lib2Target, RESOLVED_UNIT);
+    computeResult(lib3Target, RESOLVED_UNIT);
+    CompilationUnit unit = outputs[RESOLVED_UNIT];
+    ClassElement b = unit.declarations[1].element;
+    expect(b.getMethod('foo').returnType.toString(), 'int');
+
+    // add a dummy edit.
+    context.setContents(
+        lib1Source,
+        '''
+library my_lib1;
+import 'my_lib3.dart';
+var foo = 123;
+''');
+
+    computeResult(lib1Target, RESOLVED_UNIT);
+    computeResult(lib2Target, RESOLVED_UNIT);
+    computeResult(lib3Target, RESOLVED_UNIT);
+    unit = outputs[RESOLVED_UNIT];
+    b = unit.declarations[1].element;
+    expect(b.getMethod('foo').returnType.toString(), 'int',
+        reason: 'edit should not affect member inference');
+  }
+
   void test_library_cycle_incremental_partial() {
     enableStrongMode();
     Source lib1Source = newSource(
         '/my_lib1.dart',
         '''
 library my_lib1;
 ''');
     Source lib2Source = newSource(
         '/my_lib2.dart',
         '''
@@ skipping 3128 matching lines @@
   /**
    * Fill [errorListener] with [result] errors in the current [task].
    */
   void _fillErrorListener(ResultDescriptor<List<AnalysisError>> result) {
     List<AnalysisError> errors = task.outputs[result];
     expect(errors, isNotNull, reason: result.name);
     errorListener = new GatheringErrorListener();
     errorListener.addAll(errors);
   }
 }