BOOST_WORKAROUND(__clang_major__, ...) generates an undefined preprocessor symbol

[nivekkagicom]

This code in config.hpp:

#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !BOOST_WORKAROUND(BOOST_GCC, < 40900)\
      && !BOOST_WORKAROUND(BOOST_MSVC, < 1900) && !BOOST_WORKAROUND(__clang_major__, <= 4)
#  define BOOST_TT_HAS_ASCCURATE_IS_FUNCTION
#endif

Can generate a warning or error as __clang_major___WORKAROUND_GUARD is not defined.

[Hakuhonoo]

Its actually, doing this for me

[chuchusoft]

I also get this problem (using /Wall with clang-cl on Visual Studio 2019 16.6.4)

Also, the #define symbol is incorrectly spelled: BOOST_TT_HAS_ASCCURATE_IS_FUNCTION should probably be BOOST_TT_HAS_ACCURATE_IS_FUNCTION

[pdimov]

This has also been reported in boostorg/config#322.

An additional problem with this check is that __clang_major__ can be more than 4 on macOS, but Clang can still effectively be 3.x according to the official versioning, as Apple use their own versioning scheme.

[pdimov]

This is resolved by boostorg/config#383, although if boostorg/config#385 is merged it will be better to switch the check to use the new macro.