go/bindings/cgo: allocate C structs on C side

mojo/public/go/bindings/interface.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package bindings
 
 import (
+        "fmt"
         "mojo/public/go/system"
 )
 
 // MessagePipeHandleOwner owns a message pipe handle, it can only pass it
 // invalidating itself or close it.
 type MessagePipeHandleOwner struct {
         handle system.MessagePipeHandle
 }
 
 // PassMessagePipe passes ownership of the underlying message pipe handle to
@@ skipping 35 matching lines @@
         MessagePipeHandleOwner
 }
 
 // CreateMessagePipeForInterface creates a message pipe with interface request
 // on one end and interface pointer on the other end. The interface request
 // should be attached to appropriate mojo interface implementation and
 // the interface pointer should be attached to mojo interface proxy.
 func CreateMessagePipeForMojoInterface() (InterfaceRequest, InterfacePointer) {
         r, h0, h1 := system.GetCore().CreateMessagePipe(nil)
         if r != system.MOJO_RESULT_OK {
-                panic("can't create a message pipe")
+                panic(fmt.Sprintf("can't create a message pipe: %v", r))
         }
         return InterfaceRequest{MessagePipeHandleOwner{h0}}, InterfacePointer{MessagePipeHandleOwner{h1}}
 }