https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115960
--- Comment #5 from Noah Williams <noahmartinwilliams at gmail dot com> --- (In reply to Jonathan Wakely from comment #4) > > The problem seems to be that, despite passing "-std=c++17", it doesn't use > > c++17 > > header files for the Optional identifier. > > Why should it? The name "Optional" is not part of any C++ standard. It isn't? The library I was trying to compile included the "optional" header, and I had looked it up and found it was part of C++ 17, so I thought it was part of the standard.
