http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49826
--- Comment #3 from Kai Tietz <ktietz at gcc dot gnu.org> 2011-12-30 17:42:56 UTC --- Hmm, I am not that sure, if this is at all a bug, as linker can handle undecorated stdcall-s quite well as import. I am more curious for what purpose you actual need the @<n> decoration in combination with -mrtd.
