Refactor resolution code in the vm to properly handle ambiguity errors.

runtime/vm/mirrors_api_impl.cc

 // Copyright (c) 2013, 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.
 
 #include "include/dart_mirrors_api.h"
 
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_api_impl.h"
@@ skipping 324 matching lines @@
     // Case 4.  Lookup the function with a . appended to find the
     // unnamed constructor.
     if (func.IsNull()) {
       tmp_name = String::Concat(func_name, Symbols::Dot());
       func = cls.LookupFunctionAllowPrivate(tmp_name);
     }
   } else if (obj.IsLibrary()) {
     const Library& lib = Library::Cast(obj);
 
     // Case 1.  Lookup the unmodified function name.
-    func = lib.LookupFunctionAllowPrivate(func_name);
+    String& ambiguity_error_msg = String::Handle(isolate);
+    func = lib.LookupFunctionAllowPrivate(func_name, &ambiguity_error_msg);
 
     // Case 2.  Lookup the function without the external setter suffix
     // '='.  Make sure to do this check after the regular lookup, so
     // that we don't interfere with operator lookups (like ==).
-    if (func.IsNull() && HasExternalSetterSuffix(func_name)) {
+    if (func.IsNull() && ambiguity_error_msg.IsNull() &&
+        HasExternalSetterSuffix(func_name)) {
       tmp_name = RemoveExternalSetterSuffix(func_name);
       tmp_name = Field::SetterName(tmp_name);
-      func = lib.LookupFunctionAllowPrivate(tmp_name);
+      func = lib.LookupFunctionAllowPrivate(tmp_name, &ambiguity_error_msg);
     }
 
     // Case 3.  Lookup the function with the getter prefix prepended.
-    if (func.IsNull()) {
+    if (func.IsNull() && ambiguity_error_msg.IsNull()) {
       tmp_name = Field::GetterName(func_name);
-      func = lib.LookupFunctionAllowPrivate(tmp_name);
+      func = lib.LookupFunctionAllowPrivate(tmp_name, &ambiguity_error_msg);
+    }
+    if (!ambiguity_error_msg.IsNull()) {
+      return Api::NewError("%s.", ambiguity_error_msg.ToCString());
     }
   } else {
     return Api::NewError(
         "%s expects argument 'target' to be a class or library.",
         CURRENT_FUNC);
   }
 
 #if defined(DEBUG)
   if (!func.IsNull()) {
     // We only provide access to a subset of function kinds.
@@ skipping 287 matching lines @@
   if (obj.IsType() || obj.IsClass()) {
     // For backwards compatibility we allow class objects to be passed in
     // for now. This needs to be removed once all code that uses class
     // objects to invoke Dart_Invoke is removed.
     const Class& cls = (obj.IsType()) ?
         Class::Handle(Type::Cast(obj).type_class()) : Class::Cast(obj);
     return Api::NewHandle(isolate, cls.LookupField(var_name));
   }
   if (obj.IsLibrary()) {
     const Library& lib = Library::Cast(obj);
-    return Api::NewHandle(isolate, lib.LookupFieldAllowPrivate(var_name));
+    String& ambiguity_error_msg = String::Handle(isolate);
+    const Field& variable = Field::Handle(
+        lib.LookupFieldAllowPrivate(var_name, &ambiguity_error_msg));
+    if (!ambiguity_error_msg.IsNull()) {
+      return Api::NewError("%s.", ambiguity_error_msg.ToCString());
+    }
+    return Api::NewHandle(isolate, variable.raw());
   }
   return Api::NewError(
       "%s expects argument 'target' to be a class or library.",
       CURRENT_FUNC);
 }
 
 
 DART_EXPORT Dart_Handle Dart_VariableName(Dart_Handle variable) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
@@ skipping 239 matching lines @@
   } else if (obj.IsField()) {
     cls = Field::Cast(obj).origin();
   } else {
     return Api::NewHandle(isolate, Object::empty_array().raw());
   }
   const Library& lib = Library::Handle(cls.library());
   return Api::NewHandle(isolate, lib.GetMetadata(obj));
 }
 
 }  // namespace dart