John Maddock wrote:
For compilers that are effectively "dead", we could just...
In principle, what I suggest is perfectly doable with negative macros too. We put #if !defined(__cpp_foo) || __cpp_foo < 201400 # define BOOST_NO_CXX14_FOO #endif in prefix.hpp, then in the compiler-specific configs #undef the macros instead of setting them. The only reason to prefer positivity is because this way of doing things is what comes naturally when positive macros are used.
From user point of view, I've always felt that
#ifdef BOOST_CXX17_FEATURE
// use c++17 feature
#endif
reads better than the inverted test, but that's probably a matter of taste.
(This also degrades gracefully if one forgets the