https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66808
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Created attachment 37095 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37095&action=edit gcc6-pr66808.patch Untested fix. My understanding is that the tsubst_decl code just in some cases does not expect a local VAR_DECL template to have DECL_LANG_SPECIFIC set and doesn't clear some fields in it. For the __thread var DECL_LANG_SPECIFIC it is created to hold the GNU TLS bit.
