[Bug c++/100102] [9/10/11/12 Regression] ICE in tsubst, at cp/pt.c:15310

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100102

--- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> ---
cvised reproducer from PR 100448

template <bool> using __bool_constant struct intmax_t;
template <int, int> struct ratio {
  template <class _Period> struct duration {
    static intmax_t _S_gcd();
    template <class>
    using __is_harmonic =
        __bool_constant<ratio<0, _Period(duration ::_S_gcd)>::den>;
    class _Period2 __is_harmonic<_Period2>