#if defined(DUK_F_C99) || defined(DUK_F_CPP11)
/* C99 / C++11 and above: rely on va_copy() which is required. */
#define DUK_VA_COPY(dest,src) va_copy(dest,src)
#else
/* GCC: assume we have __va_copy() in non-C99 mode. */
#define DUK_VA_COPY(dest,src) __va_copy(dest,src)
#endif

#if defined(DUK_F_GCC_VERSION) && (DUK_F_GCC_VERSION >= 20500L) && (DUK_F_GCC_VERSION < 50000L)
/* Since gcc-2.5.
 *
 * Disabled temporarily in GCC 5+ because of an unresolved noreturn-related
 * issue: https://github.com/svaarala/duktape/issues/2155.
 */
#define DUK_NORETURN(decl)  decl __attribute__((noreturn))
#endif

#if defined(DUK_F_GCC_VERSION) && (DUK_F_GCC_VERSION >= 40500L)
/* Since gcc-4.5. */
#define DUK_UNREACHABLE()  do { __builtin_unreachable(); } while (0)
#endif

#define DUK_USE_BRANCH_HINTS
#if defined(DUK_F_GCC_VERSION) && (DUK_F_GCC_VERSION >= 40500L)
/* GCC: test not very accurate; enable only in relatively recent builds
 * because of bugs in gcc-4.4 (http://lists.debian.org/debian-gcc/2010/04/msg00000.html)
 */
#define DUK_LIKELY(x)    __builtin_expect((x), 1)
#define DUK_UNLIKELY(x)  __builtin_expect((x), 0)
#endif
/* XXX: equivalent of clang __builtin_unpredictable? */

#if (defined(DUK_F_C99) || defined(DUK_F_CPP11)) && \
    defined(DUK_F_GCC_VERSION) && (DUK_F_GCC_VERSION >= 30101)
#define DUK_NOINLINE        __attribute__((noinline))
#define DUK_INLINE          inline
#define DUK_ALWAYS_INLINE   inline __attribute__((always_inline))
#endif

#if (defined(DUK_F_C99) || defined(DUK_F_CPP11)) && \
    defined(DUK_F_GCC_VERSION) && (DUK_F_GCC_VERSION >= 40300)
#define DUK_HOT             __attribute__((hot))
#define DUK_COLD            __attribute__((cold))
#endif

#if defined(DUK_F_DLL_BUILD) && defined(DUK_F_WINDOWS)
#snippet "msvc_visibility.h.in"
#elif defined(DUK_F_GCC_VERSION) && (DUK_F_GCC_VERSION >= 40000)
#snippet "gcc_clang_visibility.h.in"
#endif

#if defined(DUK_F_MINGW)
#if defined(DUK_F_CPP)
#define DUK_USE_COMPILER_STRING "mingw++"
#else
#define DUK_USE_COMPILER_STRING "mingw"
#endif
#else
#if defined(DUK_F_CPP)
#define DUK_USE_COMPILER_STRING "g++"
#else
#define DUK_USE_COMPILER_STRING "gcc"
#endif
#endif

#undef DUK_USE_VARIADIC_MACROS
#if defined(DUK_F_C99) || (defined(DUK_F_CPP11) && defined(__GNUC__))
#define DUK_USE_VARIADIC_MACROS
#endif

#define DUK_USE_UNION_INITIALIZERS

#undef DUK_USE_FLEX_C99
#undef DUK_USE_FLEX_ZEROSIZE
#undef DUK_USE_FLEX_ONESIZE
#if defined(DUK_F_C99)
#define DUK_USE_FLEX_C99
#else
#define DUK_USE_FLEX_ZEROSIZE
#endif

/* Since 4.6 one can '#pragma GCC diagnostic push/pop'. */
#if defined(DUK_F_GCC_VERSION) && (DUK_F_GCC_VERSION >= 40600)
#define DUK_USE_GCC_PRAGMAS
#else
#undef DUK_USE_GCC_PRAGMAS
#endif

#define DUK_USE_PACK_GCC_ATTR

/* Availability varies based on platform (between GCC 4.4 and 4.8), and there
 * are apparently some bugs in GCC 4.x.  Check for GCC 5.0 before enabling
 * these to be safe.
 */
#if defined(DUK_F_GCC_VERSION) && (DUK_F_GCC_VERSION >= 50000L)
#define DUK_BSWAP64(x) ((duk_uint64_t) __builtin_bswap64((duk_uint64_t) (x)))
#define DUK_BSWAP32(x) ((duk_uint32_t) __builtin_bswap32((duk_uint32_t) (x)))
#define DUK_BSWAP16(x) ((duk_uint16_t) __builtin_bswap16((duk_uint16_t) (x)))
#endif