[Bug c++/115425] New: ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[hewillk at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115425

            Bug ID: 115425
           Summary: ICE: tree check: expected type_pack_expansion or
                    expr_pack_expansion, have error_mark in
                    tsubst_pack_expansion, at cp/pt.cc:13778
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

This seems like 15 regressions and may related to the constexpr static local
variable.

https://godbolt.org/z/sf4f3Woqa

#include <tuple>

template<std::size_t... Is>
void foo(std::index_sequence<Is...>);

template<auto>
struct S;

template<class T>
auto test() {
  using Seq = std::make_index_sequence<std::tuple_size_v<T>>;
  constexpr static auto x = foo<Seq>();
  return []<std::size_t... Is>(std::index_sequence<Is...>) {
    (typename S<x[Is]>::type{}, ...);
  }(std::make_index_sequence<0>{});
}

int main() {
  test<std::tuple<>>();
}