Fix use of generic function type aliases for fields (issue 29237)

pkg/analyzer/lib/src/summary/resynthesize.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 summary_resynthesizer;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
@@ skipping 1238 matching lines @@
    * If [implicitFunctionTypeIndices] is not empty, a [DartType] should be
    * created which refers to a function type implicitly defined by one of the
    * element's parameters.  [implicitFunctionTypeIndices] is interpreted as in
    * [EntityRef.implicitFunctionTypeIndices].
    *
    * If the entity referred to by this [_ReferenceInfo] is not a type, `null`
    * is returned.
    */
   DartType buildType(bool instantiateToBoundsAllowed, int numTypeArguments,
       DartType getTypeArgument(int i), List<int> implicitFunctionTypeIndices) {
-    DartType result =
-        (numTypeParameters == 0 && implicitFunctionTypeIndices.isEmpty)
-            ? type
-            : _buildType(instantiateToBoundsAllowed, numTypeArguments,
-                getTypeArgument, implicitFunctionTypeIndices);
+    DartType result;
+    if (numTypeParameters == 0 && implicitFunctionTypeIndices.isEmpty) {
+      if (element is GenericTypeAliasElementHandle) {

[scheglov, 2017/04/10 21:37:16]

Per offline discussion, this is OK to close the issue for 1.23, but we want to
make it better in the bleeding edge.

+        List<DartType> argumentTypes = <DartType>[];
+        for (int i = 0; i < numTypeArguments; i++) {
+          argumentTypes.add(getTypeArgument(i));
+        }
+        GenericTypeAliasElementImpl actualElement =
+            (element as GenericTypeAliasElementHandle).actualElement;
+        result = actualElement.typeAfterSubstitution(argumentTypes);
+      } else {
+        result = type;
+      }
+    } else {
+      result = _buildType(instantiateToBoundsAllowed, numTypeArguments,
+          getTypeArgument, implicitFunctionTypeIndices);
+    }
     if (result == null) {
       return DynamicTypeImpl.instance;
     }
     return result;
   }
 
   /**
    * If this reference refers to a type, build a [DartType].  Otherwise return
    * `null`.  If [numTypeArguments] is the same as the [numTypeParameters],
    * the type is instantiated with type arguments returned by [getTypeArgument],
@@ skipping 556 matching lines @@
             assert(location.components.length == 3);
             element = new FunctionElementHandle(summaryResynthesizer, location);
             break;
           case ReferenceKind.topLevelPropertyAccessor:
             element = new PropertyAccessorElementHandle(
                 summaryResynthesizer, location);
             break;
           case ReferenceKind.typedef:
             element = new FunctionTypeAliasElementHandle(
                 summaryResynthesizer, location);
+            if ((element as ElementHandle).actualElement

[scheglov, 2017/04/10 21:37:16]

Can we put FunctionTypeAliasElementHandle into a separate variable to avoid
casting, and then if/else put into "element"?

+                is GenericTypeAliasElement) {
+              element = new GenericTypeAliasElementHandle(

[scheglov, 2017/04/10 21:37:17]

It's a bit scary that we request the actual element, so resynthesize it here.
But probably it will work fine, we create ReferenceInfo(s) lazily.

+                  summaryResynthesizer, location);
+            }
             isDeclarableType = true;
             break;
           case ReferenceKind.variable:
             Element enclosingElement = enclosingInfo.element;
             if (enclosingElement is ExecutableElement) {
               element = new _DeferredLocalVariableElement(
                   enclosingElement, linkedReference.localIndex);
             } else {
               throw new StateError('Unexpected element enclosing variable:'
                   ' ${enclosingElement.runtimeType}');
@@ skipping 112 matching lines @@
   static String _getElementIdentifier(String name, ReferenceKind kind) {
     if (kind == ReferenceKind.topLevelPropertyAccessor ||
         kind == ReferenceKind.propertyAccessor) {
       if (!name.endsWith('=')) {
         return name + '?';
       }
     }
     return name;
   }
 }