Issue 28550. Fix for resynthesizing invalid elements as declared types.

R=paulberry@google.com
BUG= https://github.com/dart-lang/sdk/issues/28550

Review-Url: https://codereview.chromium.org/2665013002 .

pkg/analyzer/lib/src/dart/analysis/driver.dart

@@ -74,7 +74,7 @@ class AnalysisDriver {
   /**
    * The version of data format, should be incremented on every format change.
    */
-  static const int DATA_VERSION = 15;
+  static const int DATA_VERSION = 16;
 
   /**
    * The number of exception contexts allowed to write. Once this field is

pkg/analyzer/lib/src/dart/element/element.dart

@@ -3871,7 +3871,8 @@ abstract class ExecutableElementImpl extends ElementImpl
           serializedExecutable.inferredReturnTypeSlot, typeParameterContext);
       _declaredReturnType = enclosingUnit.resynthesizerContext.resolveTypeRef(
           serializedExecutable.returnType, typeParameterContext,
-          defaultVoid: isSetter && context.analysisOptions.strongMode);
+          defaultVoid: isSetter && context.analysisOptions.strongMode,
+          declaredType: true);
     }
     return _returnType ?? _declaredReturnType;
   }
@@ -4743,8 +4744,9 @@ class FunctionTypeAliasElementImpl extends ElementImpl
   @override
   DartType get returnType {
     if (_unlinkedTypedef != null && _returnType == null) {
-      _returnType = enclosingUnit.resynthesizerContext
-          .resolveTypeRef(_unlinkedTypedef.returnType, this);
+      _returnType = enclosingUnit.resynthesizerContext.resolveTypeRef(
+          _unlinkedTypedef.returnType, this,
+          declaredType: true);
     }
     return _returnType;
   }
@@ -6890,8 +6892,9 @@ abstract class NonParameterVariableElementImpl extends VariableElementImpl {
     if (_unlinkedVariable != null && _declaredType == null && _type == null) {
       _type = enclosingUnit.resynthesizerContext.resolveLinkedType(
           _unlinkedVariable.inferredTypeSlot, typeParameterContext);
-      _declaredType = enclosingUnit.resynthesizerContext
-          .resolveTypeRef(_unlinkedVariable.type, typeParameterContext);
+      _declaredType = enclosingUnit.resynthesizerContext.resolveTypeRef(
+          _unlinkedVariable.type, typeParameterContext,
+          declaredType: true);
     }
     return super.type;
   }
@@ -7379,8 +7382,9 @@ class ParameterElementImpl extends VariableElementImpl
       } else {
         _type = enclosingUnit.resynthesizerContext.resolveLinkedType(
             _unlinkedParam.inferredTypeSlot, typeParameterContext);
-        _declaredType = enclosingUnit.resynthesizerContext
-            .resolveTypeRef(_unlinkedParam.type, typeParameterContext);
+        _declaredType = enclosingUnit.resynthesizerContext.resolveTypeRef(
+            _unlinkedParam.type, typeParameterContext,
+            declaredType: true);
       }
     }
   }
@@ -7955,7 +7959,9 @@ abstract class ResynthesizerContext {
    */
   DartType resolveTypeRef(
       EntityRef type, TypeParameterizedElementMixin typeParameterContext,
-      {bool defaultVoid: false, bool instantiateToBoundsAllowed: true});
+      {bool defaultVoid: false,
+      bool instantiateToBoundsAllowed: true,
+      bool declaredType: false});
 }
 
 /**
@@ -8155,7 +8161,7 @@ class TypeParameterElementImpl extends ElementImpl
       }
       return _bound ??= enclosingUnit.resynthesizerContext.resolveTypeRef(
           _unlinkedTypeParam.bound, enclosingElement,
-          instantiateToBoundsAllowed: false);
+          instantiateToBoundsAllowed: false, declaredType: true);
     }
     return _bound;
   }

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

@@ -1061,7 +1061,9 @@ abstract class CompilationUnitElementForLink
   @override
   DartType resolveTypeRef(
       EntityRef type, TypeParameterizedElementMixin typeParameterContext,
-      {bool defaultVoid: false, bool instantiateToBoundsAllowed: true}) {
+      {bool defaultVoid: false,
+      bool instantiateToBoundsAllowed: true,
+      bool declaredType: false}) {
     if (type == null) {
       if (defaultVoid) {
         return VoidTypeImpl.instance;

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

@@ -1193,6 +1193,11 @@ class _ReferenceInfo {
    */
   final String name;
 
+  /**
+   * Is `true` if the [element] can be used as a declared type.
+   */
+  final bool isDeclarableType;
+
   /**
    * The element referred to by this reference, or `null` if there is no
    * associated element (e.g. because it is a reference to an undefined
@@ -1221,8 +1226,14 @@ class _ReferenceInfo {
    * the type itself.  Otherwise, pass `null` and the type will be computed
    * when appropriate.
    */
-  _ReferenceInfo(this.libraryResynthesizer, this.enclosing, this.name,
-      this.element, DartType specialType, this.numTypeParameters) {
+  _ReferenceInfo(
+      this.libraryResynthesizer,
+      this.enclosing,
+      this.name,
+      this.isDeclarableType,
+      this.element,
+      DartType specialType,
+      this.numTypeParameters) {
     if (specialType != null) {
       type = specialType;
     } else {
@@ -1409,10 +1420,13 @@ class _ResynthesizerContext implements ResynthesizerContext {
   @override
   DartType resolveTypeRef(
       EntityRef type, TypeParameterizedElementMixin typeParameterContext,
-      {bool defaultVoid: false, bool instantiateToBoundsAllowed: true}) {
+      {bool defaultVoid: false,
+      bool instantiateToBoundsAllowed: true,
+      bool declaredType: false}) {
     return _unitResynthesizer.buildType(type, typeParameterContext,
         defaultVoid: defaultVoid,
-        instantiateToBoundsAllowed: instantiateToBoundsAllowed);
+        instantiateToBoundsAllowed: instantiateToBoundsAllowed,
+        declaredType: declaredType);
   }
 }
 
@@ -1592,7 +1606,9 @@ class _UnitResynthesizer {
    */
   DartType buildType(
       EntityRef type, TypeParameterizedElementMixin typeParameterContext,
-      {bool defaultVoid: false, bool instantiateToBoundsAllowed: true}) {
+      {bool defaultVoid: false,
+      bool instantiateToBoundsAllowed: true,
+      bool declaredType: false}) {
     if (type == null) {
       if (defaultVoid) {
         return VoidTypeImpl.instance;
@@ -1616,6 +1632,9 @@ class _UnitResynthesizer {
       }
 
       _ReferenceInfo referenceInfo = getReferenceInfo(type.reference);
+      if (declaredType && !referenceInfo.isDeclarableType) {
+        return DynamicTypeImpl.instance;
+      }
       return referenceInfo.buildType(
           instantiateToBoundsAllowed,
           type.typeArguments.length,
@@ -1715,19 +1734,24 @@ class _UnitResynthesizer {
           : null;
       Element element;
       DartType type;
+      bool isDeclarableType = false;
       int numTypeParameters = linkedReference.numTypeParameters;
       if (linkedReference.kind == ReferenceKind.unresolved) {
         type = UndefinedTypeImpl.instance;
         element = null;
+        isDeclarableType = true;
       } else if (name == 'dynamic') {
         type = DynamicTypeImpl.instance;
         element = type.element;
+        isDeclarableType = true;
       } else if (name == 'void') {
         type = VoidTypeImpl.instance;
         element = type.element;
+        isDeclarableType = true;
       } else if (name == '*bottom*') {
         type = BottomTypeImpl.instance;
         element = null;
+        isDeclarableType = true;
       } else {
         List<String> locationComponents;
         if (enclosingInfo != null && enclosingInfo.element is ClassElement) {
@@ -1756,6 +1780,7 @@ class _UnitResynthesizer {
         switch (linkedReference.kind) {
           case ReferenceKind.classOrEnum:
             element = new ClassElementHandle(summaryResynthesizer, location);
+            isDeclarableType = true;
             break;
           case ReferenceKind.constructor:
             assert(location.components.length == 4);
@@ -1782,6 +1807,7 @@ class _UnitResynthesizer {
           case ReferenceKind.typedef:
             element = new FunctionTypeAliasElementHandle(
                 summaryResynthesizer, location);
+            isDeclarableType = true;
             break;
           case ReferenceKind.variable:
             Element enclosingElement = enclosingInfo.element;
@@ -1811,7 +1837,7 @@ class _UnitResynthesizer {
         }
       }
       result = new _ReferenceInfo(libraryResynthesizer, enclosingInfo, name,
-          element, type, numTypeParameters);
+          isDeclarableType, element, type, numTypeParameters);
       referenceInfos[index] = result;
     }
     return result;

pkg/analyzer/test/src/summary/resynthesize_common.dart

@@ -4659,6 +4659,18 @@ bool f() => true;
     checkLibrary('dynamic d;');
   }
 
+  test_type_invalid_topLevelVariableElement_asType() {
+    checkLibrary(
+        '''
+class C<T extends V> {}
+typedef V F(V p);
+V f(V p) {}
+V V2 = null;
+int V = 0;
+''',
+        allowErrors: true);
+  }
+
   test_type_invalid_typeParameter_asPrefix() {
     checkLibrary(
         '''