[Bug libstdc++/106793] std::barrier missing default template argument?

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106793

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
GCC's error is not helpful, but clang clearly explains what's wrong:

error: use of class template 'barrier' requires template arguments; argument
deduction not allowed in function prototype