https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108278
--- Comment #17 from Jakub Jelinek <jakub at gcc dot gnu.org> --- We know the commit introduced UB on the compiler side, but what I don't understand is why it triggered on the testcases you've provided. It surely introduced UB when compiling libgcc/unwind-dw2.c or during predefining macros with -fbuilding-libgcc, but I think the problematic code with uninitialized array of poly_ints could happen at different times.
