compiler: Add QEMU_BUILD_BUG_MSG() macro

_Static_assert() allows us to specify messages, and that may come in
handy.  Even without _Static_assert(), encouraging developers to put a
helpful message next to the QEMU_BUILD_BUG_* may make debugging easier
whenever it breaks.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20180224154033.29559-2-mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Max Reitz 2018-02-24 16:40:27 +01:00 committed by Eric Blake
parent 7d0f982bfb
commit 9139b56723

View File

@ -82,15 +82,21 @@
int:(x) ? -1 : 1; \
}
/* QEMU_BUILD_BUG_MSG() emits the message given if _Static_assert is
* supported; otherwise, it will be omitted from the compiler error
* message (but as it remains present in the source code, it can still
* be useful when debugging). */
#if defined(CONFIG_STATIC_ASSERT)
#define QEMU_BUILD_BUG_ON(x) _Static_assert(!(x), "not expecting: " #x)
#define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x), msg)
#elif defined(__COUNTER__)
#define QEMU_BUILD_BUG_ON(x) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \
#define QEMU_BUILD_BUG_MSG(x, msg) typedef QEMU_BUILD_BUG_ON_STRUCT(x) \
glue(qemu_build_bug_on__, __COUNTER__) __attribute__((unused))
#else
#define QEMU_BUILD_BUG_ON(x)
#define QEMU_BUILD_BUG_MSG(x, msg)
#endif
#define QEMU_BUILD_BUG_ON(x) QEMU_BUILD_BUG_MSG(x, "not expecting: " #x)
#define QEMU_BUILD_BUG_ON_ZERO(x) (sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)) - \
sizeof(QEMU_BUILD_BUG_ON_STRUCT(x)))