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

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

Index: pkg/analyzer/lib/src/summary/resynthesize.dart
diff --git a/pkg/analyzer/lib/src/summary/resynthesize.dart b/pkg/analyzer/lib/src/summary/resynthesize.dart
index a6620cc6f5b8f6920815ab98cf92b9ebfb2964e1..fc9cf16b698cd36e199c1010cd03b03a4ada0d18 100644
--- a/pkg/analyzer/lib/src/summary/resynthesize.dart
+++ b/pkg/analyzer/lib/src/summary/resynthesize.dart
@@ -1256,11 +1256,23 @@ class _ReferenceInfo {
    */
   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;
     }
@@ -1837,6 +1849,11 @@ class _UnitResynthesizer {
           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: