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Subject[PATCH v2] include/uapi/linux/swab.h: move explicit cast outside ternary
Date
A cast inside __builtin_constant_p doesn't do anything since it should evaluate
as constant at compile time irrespective of this cast. Instead, I moved this
cast outside the ternary to ensure the return type is as expected.

For instance, if __HAVE_BUILTIN_BSWAP16__ was not defined then __swab16 is
actually returning an `int` not a `u16` due to integer promotion as described
by Nick in this thread. This has repercussions when building with clang
-Wformat. This fix should solve many of these warnings.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Justin Stitt <jstitt007@gmail.com>
---
include/uapi/linux/swab.h | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/swab.h b/include/uapi/linux/swab.h
index f6be3f2e6fee..ab5a1283800c 100644
--- a/include/uapi/linux/swab.h
+++ b/include/uapi/linux/swab.h
@@ -99,10 +99,10 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val)
* @x: value to byteswap
*/
#ifdef __HAVE_BUILTIN_BSWAP16__
-#define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
+#define __swab16(x) (__u16)__builtin_bswap16(x)
#else
#define __swab16(x) \
- (__u16)(__builtin_constant_p((__u16)(x)) ? \
+ (__u16)(__builtin_constant_p(x) ? \
___constant_swab16(x) : \
__fswab16(x))
#endif
@@ -112,10 +112,10 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val)
* @x: value to byteswap
*/
#ifdef __HAVE_BUILTIN_BSWAP32__
-#define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
+#define __swab32(x) (__u32)__builtin_bswap32(x)
#else
#define __swab32(x) \
- (__builtin_constant_p((__u32)(x)) ? \
+ (__u32)(__builtin_constant_p(x) ? \
___constant_swab32(x) : \
__fswab32(x))
#endif
@@ -125,10 +125,10 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val)
* @x: value to byteswap
*/
#ifdef __HAVE_BUILTIN_BSWAP64__
-#define __swab64(x) (__u64)__builtin_bswap64((__u64)(x))
+#define __swab64(x) (__u64)__builtin_bswap64(x)
#else
#define __swab64(x) \
- (__builtin_constant_p((__u64)(x)) ? \
+ (__u64)(__builtin_constant_p(x) ? \
___constant_swab64(x) : \
__fswab64(x))
#endif
--
2.30.2
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