Fix summary handling of invalid annotations of the form `@a.b.c`.

pkg/analyzer/test/src/summary/resynthesize_common.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 test.src.serialization.elements_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
@@ skipping 514 matching lines @@
           compareConstAstLists(rType.typeArguments?.arguments,
               oType.typeArguments?.arguments, desc);
         }
         compareConstAstLists(
             r.argumentList.arguments, o.argumentList.arguments, desc);
       } else if (o is AnnotationImpl && r is AnnotationImpl) {
         expect(o.atSign.lexeme, r.atSign.lexeme, reason: desc);
         Identifier rName = r.name;
         Identifier oName = o.name;
         if (oName is PrefixedIdentifier &&
+            rName is PrefixedIdentifier &&
             o.constructorName != null &&
-            o.element != null) {
-          // E.g. `@prefix.cls.ctor`.  This gets resynthesized as `@cls.ctor`,
-          // with `cls.ctor` represented as a PrefixedIdentifier.
-          expect(rName, new isInstanceOf<PrefixedIdentifier>(), reason: desc);
-          if (rName is PrefixedIdentifier) {
-            compareConstAsts(rName.prefix, oName.identifier, desc);
-            expect(rName.period.lexeme, '.', reason: desc);
-            compareConstAsts(rName.identifier, o.constructorName, desc);
-            expect(r.period, isNull, reason: desc);
-            expect(r.constructorName, isNull, reason: desc);
-          }
+            o.element != null &&
+            r.constructorName == null) {
+          // E.g. `@prefix.cls.ctor`.  This sometimes gets resynthesized as
+          // `@cls.ctor`, with `cls.ctor` represented as a PrefixedIdentifier.
+          compareConstAsts(rName.prefix, oName.identifier, desc);
+          expect(rName.period.lexeme, '.', reason: desc);
+          compareConstAsts(rName.identifier, o.constructorName, desc);
+          expect(r.period, isNull, reason: desc);
+          expect(r.constructorName, isNull, reason: desc);
         } else {
           compareConstAsts(r.name, o.name, desc);
           expect(r.period?.lexeme, o.period?.lexeme, reason: desc);
           compareConstAsts(r.constructorName, o.constructorName, desc);
         }
         compareConstAstLists(
             r.arguments?.arguments, o.arguments?.arguments, desc);
         compareElements(r.element, o.element, desc);
         // elementAnnotation should be null; it is only used in the full AST.
         expect(o.elementAnnotation, isNull);
@@ skipping 3203 matching lines @@
 ''');
   }
 
   test_instantiateToBounds_simple() {
     checkLibrary('''
 class C<T extends num> {}
 C c;
 ''');
   }
 
+  test_invalid_annotation_prefixed_constructor() {

[scheglov, 2017/01/24 20:10:18]

Can we also add tests for using static const field as annotation, like
test_invalidAnnotation_constantVariable_field_importWithPrefix does?

And probably corresponding summary_common.dart changes to test for these cases
are serialized.

+    addLibrarySource(
+        '/a.dart',
+        r'''
+class C {
+  const C.named();
+}
+''');
+    checkLibrary('''
+import "a.dart" as a;
+@a.C.named
+class D {}
+''');
+  }
+
+  test_invalid_annotation_unprefixed_constructor() {
+    addLibrarySource(
+        '/a.dart',
+        r'''
+class C {
+  const C.named();
+}
+''');
+    checkLibrary('''
+import "a.dart";
+@C.named
+class D {}
+''');
+  }
+
   test_library() {
     checkLibrary('');
   }
 
   test_library_documented() {
     checkLibrary('''
 // Extra comment so doc comment offset != 0
 /**
  * Docs
  */
@@ skipping 1158 matching lines @@
       fail('Unexpectedly tried to get unlinked summary for $uri');
     }
     return serializedUnit;
   }
 
   @override
   bool hasLibrarySummary(String uri) {
     return true;
   }
 }