From d4ddb330c952f8611dcf67c81ca67011df1bd961 Mon Sep 17 00:00:00 2001 From: Dimitry Andric Date: Sat, 24 Mar 2012 10:07:21 +0000 Subject: [PATCH] Fix the following clang warning in sys/dev/dcons/dcons.c, caused by the recent changes in sys/x86/include/endian.h: sys/dev/dcons/dcons.c:190:15: error: implicit conversion from '__uint32_t' (aka 'unsigned int') to '__uint16_t' (aka 'unsigned short') changes value from 1684238190 to 28526 [-Werror,-Wconstant-conversion] buf->magic = ntohl(DCONS_MAGIC); ^~~~~~~~~~~~~~~~~~ sys/sys/param.h:306:18: note: expanded from: #define ntohl(x) __ntohl(x) ^ ./x86/endian.h:128:20: note: expanded from: #define __ntohl(x) __bswap32(x) ^ ./x86/endian.h:78:20: note: expanded from: __bswap32_gen((__uint32_t)(x)) : __bswap32_var(x)) ^ ./x86/endian.h:68:26: note: expanded from: (((__uint32_t)__bswap16(x) << 16) | __bswap16((x) >> 16)) ^ ./x86/endian.h:75:53: note: expanded from: __bswap16_gen((__uint16_t)(x)) : __bswap16_var(x))) ~~~~~~~~~~~~~ ^ This is because the __bswapXX_gen() macros (for x86) call the regular __bswapXX() macros. Since the __bswapXX_gen() variants are only called when their arguments are constant, there is no need to do that constancy check recursively. Also, it causes the above error with clang. Fix it by calling __bswap16_gen() from __bswap32_gen(), and similarly, __bswap32_gen() from __bswap64_gen(). While here, add extra parentheses around the __bswap16_gen() macro expansion, to prevent unexpected side effects. --- sys/x86/include/endian.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/sys/x86/include/endian.h b/sys/x86/include/endian.h index 2f95320b29e..905958799c3 100644 --- a/sys/x86/include/endian.h +++ b/sys/x86/include/endian.h @@ -63,11 +63,11 @@ #define BYTE_ORDER _BYTE_ORDER #endif -#define __bswap16_gen(x) (__uint16_t)((x) << 8 | (x) >> 8) +#define __bswap16_gen(x) ((__uint16_t)((x) << 8 | (x) >> 8)) #define __bswap32_gen(x) \ - (((__uint32_t)__bswap16(x) << 16) | __bswap16((x) >> 16)) + (((__uint32_t)__bswap16_gen(x) << 16) | __bswap16_gen((x) >> 16)) #define __bswap64_gen(x) \ - (((__uint64_t)__bswap32(x) << 32) | __bswap32((x) >> 32)) + (((__uint64_t)__bswap32_gen(x) << 32) | __bswap32_gen((x) >> 32)) #ifdef __GNUCLIKE_BUILTIN_CONSTANT_P #define __bswap16(x) \