https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71174
--- Comment #2 from JD <t at sharklasers dot com> --- $ g++ -std=c++1z -Wall -Wextra -fconcepts bug.cpp bug.cpp:10:32: error: concept ‘constexpr bool InputIterator(T)’ declared with function parameters concept bool InputIterator(T it) { ^ g++: internal compiler error: Segmentation fault (program cc1plus) Please submit a full bug report, with preprocessed source if appropriate.