Wrap lazy compilation errors when parsing metadata. Addresses the poor error reporting in issue 120…

runtime/lib/mirrors.cc

 // 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.
 
 #include "include/dart_api.h"
 #include "include/dart_debugger_api.h"
 #include "include/dart_mirrors_api.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_api_state.h"  // TODO(11742): Remove with CreateMirrorRef.
 #include "vm/bootstrap_natives.h"
@@ skipping 963 matching lines @@
                                                  name_handle,
                                                  lib_mirror);
   if (Dart_IsError(result)) {
     Dart_PropagateError(result);
   }
   Dart_SetReturnValue(args, result);
   Dart_ExitScope();
 }
 
 
+static void ThrowMirroredCompilationError(const String& message) {
+  Array& args = Array::Handle(Array::New(1));
+  args.SetAt(0, message);
+
+  Exceptions::ThrowByType(Exceptions::kMirroredCompilationError, args);
+  UNREACHABLE();
+}
+
+
+static void ThrowInvokeError(const Error& error) {
+  if (error.IsLanguageError()) {
+    // A compilation error that was delayed by lazy compilation.
+    const LanguageError& compilation_error = LanguageError::Cast(error);
+    String& message = String::Handle(compilation_error.message());
+    ThrowMirroredCompilationError(message);
+    UNREACHABLE();
+  }
+  Exceptions::PropagateError(error);
+  UNREACHABLE();
+}
+
+
 DEFINE_NATIVE_ENTRY(DeclarationMirror_metadata, 1) {
   const MirrorReference& decl_ref =
       MirrorReference::CheckedHandle(arguments->NativeArgAt(0));
   const Object& decl = Object::Handle(decl_ref.referent());
 
   Class& klass = Class::Handle();
   if (decl.IsClass()) {
     klass ^= decl.raw();
   } else if (decl.IsFunction()) {
     klass = Function::Cast(decl).origin();
   } else if (decl.IsField()) {
     klass = Field::Cast(decl).origin();
   } else {
     return Object::empty_array().raw();
   }
 
   const Library& library = Library::Handle(klass.library());
-  return library.GetMetadata(decl);
+  const Object& metadata = Object::Handle(library.GetMetadata(decl));
+  if (metadata.IsError()) {
+    ThrowInvokeError(Error::Cast(metadata));
+  }
+  return metadata.raw();
 }
 
 
 void HandleMirrorsMessage(Isolate* isolate,
                           Dart_Port reply_port,
                           const Instance& message) {
   UNIMPLEMENTED();
 }
 
 
-static void ThrowMirroredCompilationError(const String& message) {
-  Array& args = Array::Handle(Array::New(1));
-  args.SetAt(0, message);
-
-  Exceptions::ThrowByType(Exceptions::kMirroredCompilationError, args);
-  UNREACHABLE();
-}
-
-
-static void ThrowInvokeError(const Error& error) {
-  if (error.IsLanguageError()) {
-    // A compilation error that was delayed by lazy compilation.
-    const LanguageError& compilation_error = LanguageError::Cast(error);
-    String& message = String::Handle(compilation_error.message());
-    ThrowMirroredCompilationError(message);
-    UNREACHABLE();
-  }
-  Exceptions::PropagateError(error);
-  UNREACHABLE();
-}
-
-
 static bool FieldIsUninitialized(const Field& field) {
   ASSERT(!field.IsNull());
 
   // Return getter method for uninitialized fields, rather than the
   // field object, since the value in the field object will not be
   // initialized until the first time the getter is invoked.
   const Instance& value = Instance::Handle(field.value());
   ASSERT(value.raw() != Object::transition_sentinel().raw());
   return value.raw() == Object::sentinel().raw();
 }
@@ skipping 726 matching lines @@
 
 DEFINE_NATIVE_ENTRY(VariableMirror_type, 1) {
   GET_NON_NULL_NATIVE_ARGUMENT(MirrorReference, ref, arguments->NativeArgAt(0));
   const Field& field = Field::Handle(ref.GetFieldReferent());
 
   const AbstractType& type = AbstractType::Handle(field.type());
   return CreateTypeMirror(type);
 }
 
 }  // namespace dart