GCC (under -Werror=undef) whines about span_HAVE_INLINE_NAMESPACE and span_CONFIG_CONTRACT_VIOLATION_THROWS_V macros not being defined. The former one was actually missing a proper definition (C++11 and MSVC 14.0 have inline namespaces). The latter was a misuse: checking for an undefined macro's value.
GCC (under -Werror=undef) whines about
span_HAVE_INLINE_NAMESPACE
andspan_CONFIG_CONTRACT_VIOLATION_THROWS_V
macros not being defined. The former one was actually missing a proper definition (C++11 and MSVC 14.0 have inline namespaces). The latter was a misuse: checking for an undefined macro's value.I made the changes myself, but I'm not sure whether I should PR this.