https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115305
--- Comment #7 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- They might come from https://gcc.gnu.org/cgi-bin/gcc-gitref.cgi?r=r15-615 and, in particular, the change made to libgnarl/s-osinte__darwin.ads, in which case the way out would be to duplicate libgnat/s-oslock__posix.ads into libgnat/s-oslock__darwin.ads, add back the sig field and remove the alignment clause there, and then do the substitution on line 2749 of Makefile.rtl.
