fix generic function expressions, part of #25175

[email protected]

Review URL: https://codereview.chromium.org/1579303002 .

Author: John Messerly

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

@@ -216,22 +216,8 @@ class FunctionTypeImpl extends TypeImpl implements FunctionType {
    * Private constructor.
    */
   FunctionTypeImpl._(TypeParameterizedElement element, String name,
-      this.prunedTypedefs, List<DartType> typeArguments, this._isInstantiated)
-      : super(element, name) {
-    if (typeArguments == null) {
-      // TODO(jmesserly): reuse TypeParameterTypeImpl.getTypes once we can
-      // make it generic, which will allow it to return List<DartType> instead
-      // of List<TypeParameterType>.
-      if (typeParameters.isEmpty) {
-        typeArguments = DartType.EMPTY_LIST;
-      } else {
-        typeArguments = new List<DartType>.from(
-            typeParameters.map((t) => t.type),
-            growable: false);
-      }
-    }
-    _typeArguments = typeArguments;
-  }
+      this.prunedTypedefs, this._typeArguments, this._isInstantiated)
+      : super(element, name);
 
   /**
    * Return the base parameter elements of this function element.
@@ -493,7 +479,21 @@ class FunctionTypeImpl extends TypeImpl implements FunctionType {
   /**
    * A list containing the actual types of the type arguments.
    */
-  List<DartType> get typeArguments => _typeArguments;
+  List<DartType> get typeArguments {
+    if (_typeArguments == null) {
+      // TODO(jmesserly): reuse TypeParameterTypeImpl.getTypes once we can
+      // make it generic, which will allow it to return List<DartType> instead
+      // of List<TypeParameterType>.
+      if (typeParameters.isEmpty) {
+        _typeArguments = DartType.EMPTY_LIST;
+      } else {
+        _typeArguments = new List<DartType>.from(
+            typeParameters.map((t) => t.type),
+            growable: false);
+      }
+    }
+    return _typeArguments;
+  }
 
   @override
   List<TypeParameterElement> get typeParameters {

pkg/analyzer/lib/src/generated/resolver.dart

@@ -3100,10 +3100,6 @@ class ElementBuilder extends RecursiveAstVisitor<Object> {
     if (_functionTypesToFix != null) {
       _functionTypesToFix.add(element);
     } else {
-      // TODO(jmesserly): for local functions inside of top-level generic
-      // functions, this is probably not right. The function type should be set
-      // after the enclosingElement is set, otherwise we won't be able to
-      // substitute those type parameters later.
       element.type = new FunctionTypeImpl(element);
     }
     element.hasImplicitReturnType = true;

pkg/analyzer/test/generated/resolver_test.dart

@@ -13043,6 +13043,8 @@ var topG = topF;
 void test/*<S>*/(/*=T*/ pf/*<T>*/(/*=T*/ e)) {
   var c = new C<int>();
   /*=T*/ lf/*<T>*/(/*=T*/ e) => null;
+
+  var lambdaCall = (/*<E>*/(/*=E*/ e) => e)/*<int>*/(3);
   var methodCall = (c.f)/*<int>*/(3);
   var staticCall = (C.g)/*<int>*/(3);
   var staticFieldCall = (C.h)/*<int>*/(3);
@@ -13059,6 +13061,7 @@ void test/*<S>*/(/*=T*/ pf/*<T>*/(/*=T*/ e)) {
     expect(_findIdentifier('topFieldCall').staticType.toString(), "int");
     expect(_findIdentifier('localCall').staticType.toString(), "int");
     expect(_findIdentifier('paramCall').staticType.toString(), "int");
+    expect(_findIdentifier('lambdaCall').staticType.toString(), "int");
   }
 
   void fail_genericMethod_functionExpressionInvocation_inferred() {
@@ -13074,6 +13077,8 @@ var topG = topF;
 void test/*<S>*/(/*=T*/ pf/*<T>*/(/*=T*/ e)) {
   var c = new C<int>();
   /*=T*/ lf/*<T>*/(/*=T*/ e) => null;
+
+  var lambdaCall = (/*<E>*/(/*=E*/ e) => e)(3);
   var methodCall = (c.f)(3);
   var staticCall = (C.g)(3);
   var staticFieldCall = (C.h)(3);
@@ -13090,6 +13095,7 @@ void test/*<S>*/(/*=T*/ pf/*<T>*/(/*=T*/ e)) {
     expect(_findIdentifier('topFieldCall').staticType.toString(), "int");
     expect(_findIdentifier('localCall').staticType.toString(), "int");
     expect(_findIdentifier('paramCall').staticType.toString(), "int");
+    expect(_findIdentifier('lambdaCall').staticType.toString(), "int");
   }
 
   void fail_genericMethod_functionInvocation_inferred() {