Check if signatures are compatible in a redirecting factory before synthesizing a call in the infer…

sdk/lib/_internal/compiler/implementation/resolution/members.dart

 // Copyright (c) 2012, 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.
 
 part of resolution;
 
 abstract class TreeElements {
   Element get currentElement;
   Set<Node> get superUses;
 
@@ skipping 2635 matching lines @@
       return;
     }
 
     // Check that the target constructor is type compatible with the
     // redirecting constructor.
     ClassElement targetClass = redirectionTarget.getEnclosingClass();
     InterfaceType type = mapping.getType(node.expression);
     FunctionType targetType = redirectionTarget.computeType(compiler)
         .subst(type.typeArguments, targetClass.typeVariables);
     FunctionType constructorType = constructor.computeType(compiler);
-    if (!compiler.types.isSubtype(targetType, constructorType)) {
+    bool isSubtype = compiler.types.isSubtype(targetType, constructorType);
+    if (!isSubtype) {
       warning(node, MessageKind.NOT_ASSIGNABLE.warning,
               {'fromType': targetType, 'toType': constructorType});
     }
 
     FunctionSignature targetSignature =
         redirectionTarget.computeSignature(compiler);
     FunctionSignature constructorSignature =
         constructor.computeSignature(compiler);
     if (!targetSignature.isCompatibleWith(constructorSignature)) {
+      assert(!isSubtype);
       compiler.backend.registerThrowNoSuchMethod(mapping);
     }
 
     // TODO(ahe): Check that this doesn't lead to a cycle.  For now,
     // just make sure that the redirection target isn't itself a
     // redirecting factory.
     { // This entire block is temporary code per the above TODO.
       FunctionElement targetImplementation = redirectionTarget.implementation;
       FunctionExpression function = targetImplementation.parseNode(compiler);
       if (function != null
@@ skipping 1547 matching lines @@
     return e;
   }
 
   /// Assumed to be called by [resolveRedirectingFactory].
   Element visitReturn(Return node) {
     Node expression = node.expression;
     return finishConstructorReference(visit(expression),
                                       expression, expression);
   }
 }