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utils: fix build error with g++

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g++ does not support __builtin_choose_expr, so we can't support
byte swapping as constant expression there.

Reported-by: Cleynhens Stijn <Stijn.Cleynhens@technicolor.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau 2018-04-12 10:26:22 +02:00
parent ace64897d4
commit 6eff829d78
1 changed files with 9 additions and 0 deletions
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9
utils.h
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@ -127,9 +127,18 @@ int clock_gettime(int type, struct timespec *tv);
#define __eval_once(func, x) \ #define __eval_once(func, x) \
({ __typeof__(x) __x = x; func(__x); }) ({ __typeof__(x) __x = x; func(__x); })
#ifdef __cplusplus
/*
* g++ does not support __builtin_choose_expr, so always use __eval_once.
* Unfortunately this means that the byte order functions can't be used
* as a constant expression anymore
*/
#define __eval_safe(func, x) __eval_once(func, x)
#else
#define __eval_safe(func, x) \ #define __eval_safe(func, x) \
__builtin_choose_expr(__is_constant(x), \ __builtin_choose_expr(__is_constant(x), \
func(x), __eval_once(func, x)) func(x), __eval_once(func, x))
#endif
#if __BYTE_ORDER == __LITTLE_ENDIAN #if __BYTE_ORDER == __LITTLE_ENDIAN