BOOST_HAS_BUILTIN/BOOST_HAS_INCLUDE

[gpeterhoff]

BOOST_HAS_BUILTIN
e.g. clang/gcc support __has_builtin. However, you have to check if this is actually available before using it. I think it would be useful to introduce a macro BOOST_HAS_BUILTIN to avoid redundant queries:

#if defined(__has_builtin)
#define BOOST_HAS_BUILTIN(ARG) __has_builtin(ARG)
#else
#define BOOST_HAS_BUILTIN(ARG) 0
#endif

Maybe you can extend this for other compilers.

BOOST_HAS_INCLUDE
__has_include is only available from C++17 on. Maybe you have an idea how to implement/provide this for older versions, a la

#if defined(__has_include)
#define BOOST_HAS_INCLUDE(ARG) __has_include(ARG)
#else
???
#endif

thx
Gero