Downwards inference on non-generic constructor parameters (fixes #25106)

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

 // Copyright (c) 2014, 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 engine.resolver;
 
 import 'dart:collection';
 
 import '../task/strong/info.dart' show InferredType, StaticInfo;
 import '../task/strong/rules.dart' show TypeRules;
@@ skipping 11697 matching lines @@
           new List<Map<VariableElement, DartType>>();
       perBranchOverrides.add(thenOverrides);
       perBranchOverrides.add(elseOverrides);
       _overrideManager.mergeOverrides(perBranchOverrides);
     }
     return null;
   }
 
   @override
   Object visitInstanceCreationExpression(InstanceCreationExpression node) {
-    DartType contextType = InferenceContext.getType(node);
-    if (contextType is InterfaceType &&
-        contextType.typeArguments != null &&
-        contextType.typeArguments.length > 0) {
-      TypeName classTypeName = node.constructorName.type;
-      if (classTypeName.typeArguments == null) {
+    TypeName classTypeName = node.constructorName.type;
+    if (classTypeName.typeArguments == null) {
+      DartType contextType = InferenceContext.getType(node);
+      if (contextType is InterfaceType &&
+          contextType.typeArguments != null &&
+          contextType.typeArguments.length > 0) {
         List<DartType> targs =
             inferenceContext.matchTypes(classTypeName.type, contextType);
         if (targs != null && targs.any((t) => !t.isDynamic)) {
           ClassElement classElement = classTypeName.type.element;
           InterfaceType rawType = classElement.type;
           InterfaceType fullType =
               rawType.substitute2(targs, rawType.typeArguments);
           // The element resolver uses the type on the constructor name, so
           // infer it first
           typeAnalyzer.inferConstructorName(node.constructorName, fullType);
-          safelyVisit(node.constructorName);
-          ConstructorElement invokedConstructor =
-              node.constructorName.staticElement;
-          FunctionType rawConstructorType = invokedConstructor.type;
-          FunctionType constructorType = rawConstructorType.substitute2(
-              targs, rawConstructorType.typeArguments);
-          InferenceContext.setType(node.argumentList, constructorType);
-          safelyVisit(node.argumentList);
-          InferenceContext.setType(node, fullType);
-          node.accept(elementResolver);
-          node.accept(typeAnalyzer);
-          return null;
         }
-      } else {
-        InferenceContext.clearType(node);
       }
     }
-    super.visitInstanceCreationExpression(node);
+    safelyVisit(node.constructorName);
+    FunctionType constructorType = node.constructorName.staticElement?.type;
+    if (constructorType != null) {
+      InferenceContext.setType(node.argumentList, constructorType);
+    }
+    safelyVisit(node.argumentList);
+    node.accept(elementResolver);
+    node.accept(typeAnalyzer);
     return null;
   }
 
   @override
   Object visitLabel(Label node) => null;
 
   @override
   Object visitLibraryIdentifier(LibraryIdentifier node) => null;
 
   @override
@@ skipping 4315 matching lines @@
     nonFields.add(node);
     return null;
   }
 
   @override
   Object visitNode(AstNode node) => node.accept(TypeResolverVisitor_this);
 
   @override
   Object visitWithClause(WithClause node) => null;
 }