Warning whe compiling with -Wundef on clang #186
Description
When compiling with -Wundef on clang we get the following warning
/xxx/modular-boost3/boost/type_traits/is_nothrow_move_constructible.hpp:30:79: warning: 'BOOST_GCC_VERSION_WORKAROUND_GUARD' is not defined, evaluates to 0 [-Werror,-Wundef]
#elif !defined(BOOST_NO_CXX11_NOEXCEPT) && !defined(BOOST_NO_SFINAE_EXPR) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40800)
^
/Users/viboes/github/modular-boost3/boost/config/workaround.hpp:244:10: note: expanded from macro 'BOOST_WORKAROUND'
((symbol ## _WORKAROUND_GUARD + 0 == 0) && \
^
<scratch space>:222:1: note: expanded from here
BOOST_GCC_VERSION_WORKAROUND_GUARD
^
This is because BOOST_GCC_VERSION_WORKAROUND_GUARD is not defined and used in an expression.
The following fixes the issue.
#ifndef BOOST_GCC
#define BOOST_GCC_WORKAROUND_GUARD 1
#define BOOST_GCC_VERSION_WORKAROUND_GUARD 1
#else
#define BOOST_GCC_WORKAROUND_GUARD 0
#define BOOST_GCC_VERSION_WORKAROUND_GUARD 0
#endif
``