Some versions of gcc produce a spurious warning if the result of
__atomic_compare_echange_n() is not used and the type involved
is a signed 8 bit value:
error: value computed is not used [-Werror=unused-value]
This has been seen on at least
gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
Work around this by using an explicit cast to void to indicate
that we don't care about the return value.
We don't currently use our atomic_cmpxchg() macro on any signed
8 bit types, but the upcoming support for the Arm v8.1-Atomics
will require it.
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
---
include/qemu/atomic.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index d73c9e14d7..9ed39effd3 100644
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -187,7 +187,7 @@
/* Returns the eventual value, failed or not */
#define atomic_cmpxchg__nocheck(ptr, old, new) ({ \
typeof_strip_qual(*ptr) _old = (old); \
- __atomic_compare_exchange_n(ptr, &_old, new, false, \
+ (void)__atomic_compare_exchange_n(ptr, &_old, new, false, \
__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); \
_old; \
})
--
2.17.0
