*/
#if defined(_MSC_VER)
-# if _MSC_VER < 1800
-# error "Microsoft Visual Studio 2013 or higher required"
+# if _MSC_VER < 1900
+# error "Microsoft Visual Studio 2015 or higher required"
# endif
/*
#endif
+/* Fallback definitions, for scons which doesn't auto-detect these things. */
+#ifdef HAVE_SCONS
+
+# ifndef _WIN32
+# define HAVE_PTHREAD
+# define HAVE_POSIX_MEMALIGN
+# endif
+
+# ifdef __GNUC__
+# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 2)
+# error "GCC version 4.2 or higher required"
+# endif
+
+ /* https://gcc.gnu.org/onlinedocs/gcc-4.2.4/gcc/Other-Builtins.html */
+# define HAVE___BUILTIN_CLZ 1
+# define HAVE___BUILTIN_CLZLL 1
+# define HAVE___BUILTIN_CTZ 1
+# define HAVE___BUILTIN_EXPECT 1
+# define HAVE___BUILTIN_FFS 1
+# define HAVE___BUILTIN_FFSLL 1
+# define HAVE___BUILTIN_POPCOUNT 1
+# define HAVE___BUILTIN_POPCOUNTLL 1
+ /* https://gcc.gnu.org/onlinedocs/gcc-4.2.4/gcc/Function-Attributes.html */
+# define HAVE_FUNC_ATTRIBUTE_FLATTEN 1
+# define HAVE_FUNC_ATTRIBUTE_UNUSED 1
+# define HAVE_FUNC_ATTRIBUTE_FORMAT 1
+# define HAVE_FUNC_ATTRIBUTE_PACKED 1
+# define HAVE_FUNC_ATTRIBUTE_ALIAS 1
+# define HAVE_FUNC_ATTRIBUTE_NORETURN 1
+
+# if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
+ /* https://gcc.gnu.org/onlinedocs/gcc-4.3.6/gcc/Other-Builtins.html */
+# define HAVE___BUILTIN_BSWAP32 1
+# define HAVE___BUILTIN_BSWAP64 1
+# endif
+
+# if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
+# define HAVE___BUILTIN_UNREACHABLE 1
+# endif
+
+# endif /* __GNUC__ */
+
+#endif /* HAVE_SCONS */
+
+
#endif /* _C99_COMPAT_H_ */