Mojo C++ bindings: better log message for serialization warnings.

mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl

 {%- import "interface_macros.tmpl" as interface_macros %}
 {%- set class_name = interface.name %}
 {%- set proxy_name = interface.name ~ "Proxy" %}
 {%- set namespace_as_string = "%s"|format(namespace|replace(".","::")) %}
 
 {%- macro alloc_params(parameters) %}
 {%-   for param in parameters %}
 {%-     if param.kind|is_object_kind  %}
 {{param.kind|cpp_result_type}} p{{loop.index}};
 Deserialize_(params->{{param.name}}.ptr, &p{{loop.index}});
@@ skipping 44 matching lines @@
 {%-       if param.kind|is_any_array_kind %}
   mojo::SerializeArray_<{{param.kind|get_array_validate_params|indent(24)}}>(
       mojo::internal::Forward(in_{{param.name}}), builder.buffer(), &params->{{param.name}}.ptr);
 {%-       else %}
   Serialize_(mojo::internal::Forward(in_{{param.name}}), builder.buffer(), &params->{{param.name}}.ptr);
 {%-       endif %}
 {%-       if not param.kind|is_nullable_kind %}
   MOJO_INTERNAL_DLOG_SERIALIZATION_WARNING(
       mojo::internal::IsNonNullableValidationEnabled() &&
           !params->{{param.name}}.ptr,
-      mojo::internal::VALIDATION_ERROR_UNEXPECTED_NULL_POINTER);
+      mojo::internal::VALIDATION_ERROR_UNEXPECTED_NULL_POINTER,
+      "null {{param.name}} argument");

[hansmuller, 2014/08/21 00:26:40]

It might be useful to include the name of the interface in the error message.
Likewise for the handle case below.

[yzshen1, 2014/08/21 05:57:49]

Done.

 {%-       endif %}
 {%-     elif param.kind|is_any_handle_kind %}
 {%-       if param.kind|is_interface_kind or
              param.kind|is_interface_request_kind %}
   // Delegate handle.
   params->{{param.name}} = in_{{param.name}}.PassMessagePipe().release();
 {%-       else %}
   params->{{param.name}} = in_{{param.name}}.release();
 {%-       endif %}
 {%-       if not param.kind|is_nullable_kind %}
   MOJO_INTERNAL_DLOG_SERIALIZATION_WARNING(
       mojo::internal::IsNonNullableValidationEnabled() &&
           !params->{{param.name}}.is_valid(),
-      mojo::internal::VALIDATION_ERROR_UNEXPECTED_INVALID_HANDLE);
+      mojo::internal::VALIDATION_ERROR_UNEXPECTED_INVALID_HANDLE,
+      "invalid {{param.name}} argument");
 {%-       endif %}
 {%-     else %}
   params->{{param.name}} = in_{{param.name}};
 {%-     endif %}
 {%-   endfor %}
   mojo::Message message;
   params->EncodePointersAndHandles(message.mutable_handles());
   builder.Finish(&message);
 {%- endmacro %}
 
@@ skipping 231 matching lines @@
       }
       break;
     }
 {%-   endfor %}
   }
 {%- endif %}
 
   return sink_->Accept(message);
 }
 {%- endif -%}