https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95324
Bug ID: 95324 Summary: Segmentation fault when using variadic lambda template in concept definition Product: gcc Version: 10.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: ivan.pogrebnyak at gmail dot com Target Milestone: --- Created attachment 48600 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48600&action=edit gcc version, output, and -save-temps Definition of the following concept (using C++20) causes segmentation fault in GCC 10.1.0. template <typename F, typename T> concept Applyable = []<size_t... I>(std::index_sequence<I...>) { return std::is_invocable_v<F,std::tuple_element_t<I,T>...>; }(std::make_index_sequence<std::tuple_size_v<T>>{}); Refactoring the definition into a `constexpr bool` and using it in the concept definition works. See the attachment for details.