https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105304
Bug ID: 105304 Summary: ICE segfault using ad-hoc concept with -Wall Product: gcc Version: 11.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: bjoern at hoehrmann dot de Target Milestone: --- GCC 11.2.0 on Linux ❯ g++-11 -Wall -std=c++2a -o x ../mini.cxx ../mini.cxx: In function 'int main()': ../mini.cxx:23:18: internal compiler error: Segmentation fault 23 | }) { | ^ Please submit a full bug report, Code: #include <iostream> #include <utility> class X { public: int m(int, int, int = 7) { return 123; } }; template<typename... Ts> void invoke_m(std::index_sequence_for<Ts...> is) { X o; o.m(Ts()...); } int main() { if constexpr (requires { invoke_m<int, int, int, int>(std::make_index_sequence<4>()); }) { std::cerr << "ok" << '\n'; } return 0; } Compiles when omitting -Wall.