https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100465
Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2021-05-07 Ever confirmed|0 |1 Status|UNCONFIRMED |NEW --- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> --- The difference is this change from g:e7406c364496dae51ef294b5720923fe4a1dfccb @@ -1082,7 +1085,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 #endif if (__add_slash) __str += __slash; - __str += __elem._M_pathname; + __str += basic_string_view<value_type>(__elem._M_pathname); __add_slash = __elem._M_type() == _Type::_Filename; } } Previously it was adding a std::string to a basic_string<char, char_traits<char>, Alloc>, which only worked if the Alloc was std::allocator<char>. The change to use string_view is required, but results in this error. I'll try to reduce the testcase.