[Bug c++/114933] [15 Regression] mcfgthread-1.6.1 typecheck failure: error: explicit specializations are not permitted here

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114933

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The easy fix is to do:
    extern "C++" {  template<bool> struct __MCF_static_assert; }
    extern "C++" { template<> struct __MCF_static_assert<true> { }; }

Note from the commit message:
    However there are also a couple of changes made to linkage specifiers
    ('extern "C"'); I've applied these as since C++20, to line up with when
    modules were actually introduced.