https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109556
Patrick Palka <ppalka at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords|needs-bisection, | |needs-reduction | --- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> --- template<typename T, auto N> concept C = (N != 0); template<auto N, auto M> struct A { }; template<auto N, C<N> auto M> void f(A<N, M>); int main() { f(A<1, 42>{}); f(A<2, 42>{}); } Bisection seems unreliable probably due to the use-after-free nature of the bug, but removing those calls to ggc_free fixes the issue so r13-377-g3e948d645bc908 is almost certainly the culprit.