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Subject[PATCH v3] include/uapi/linux/swab.h: move explicit cast outside ternary
Date
From: Justin Stitt <jstitt007@gmail.com>

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.

Additionally, if __HAVE_BUILTIN_BSWAP16__ was not defined then __swab16
is actually returning an `int` not a `u16` due to integer promotion.

As Al Viro notes:
You *can't* get smaller-than-int out of ? :, same as you can't get it
out of addition, etc.

This also fixes some clang -Wformat warnings involving default
argument promotion.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Justin Stitt <jstitt007@gmail.com>
---
diff from v2 -> v3:
* re-insert respective (u16, u32, u64) cast to __builtin_bswap as per
Nick's suggestion
* added note from Al Viro

include/uapi/linux/swab.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/uapi/linux/swab.h b/include/uapi/linux/swab.h
index 7272f85d6d6a..0723a9cce747 100644
--- a/include/uapi/linux/swab.h
+++ b/include/uapi/linux/swab.h
@@ -102,7 +102,7 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val)
#define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
#else
#define __swab16(x) \
- (__builtin_constant_p((__u16)(x)) ? \
+ (__u16)(__builtin_constant_p(x) ? \
___constant_swab16(x) : \
__fswab16(x))
#endif
@@ -115,7 +115,7 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val)
#define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
#else
#define __swab32(x) \
- (__builtin_constant_p((__u32)(x)) ? \
+ (__u32)(__builtin_constant_p(x) ? \
___constant_swab32(x) : \
__fswab32(x))
#endif
@@ -128,7 +128,7 @@ static inline __attribute_const__ __u32 __fswahb32(__u32 val)
#define __swab64(x) (__u64)__builtin_bswap64((__u64)(x))
#else
#define __swab64(x) \
- (__builtin_constant_p((__u64)(x)) ? \
+ (__u64)(__builtin_constant_p(x) ? \
___constant_swab64(x) : \
__fswab64(x))
#endif
--
2.36.1.476.g0c4daa206d-goog
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