https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85670
Jordi Vilar <development at jordi dot vilar.cat> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |development at jordi dot vilar.cat --- Comment #4 from Jordi Vilar <development at jordi dot vilar.cat> --- No only operator != is referenced (line 237) before it is declared (line 550). Also __is_encoded_char is instantiated (line 412) before it is specialized (line 511) via the constructor (line 180). In both cases, it only happens if the _GLIBCXX_FILESYSTEM_IS_WINDOWS is defined. And finally, both overloads of u8path must be introduced in the reversed order. I managed to compile just #include <filesystem>, but then it fails with <fstream> as it is not able to open file streams with a path object (it looks like it lacks a constructor with const wchar_t*)