From e4749953c309cb418cd583cdd80b6dd0b2c4161f Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Fri, 24 Oct 2014 17:13:39 -0400 Subject: [PATCH] Fix: silence gcc -Wextra warning It appears that just casting to "unsigned long" already has the semantic we are looking for (checked by reading C99 standard and experimentation): it sign-extends smaller signed integers, and does not sign-extend unsigned integers. Signed-off-by: Mathieu Desnoyers --- urcu/compiler.h | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/urcu/compiler.h b/urcu/compiler.h index 2e0237e..4b31855 100644 --- a/urcu/compiler.h +++ b/urcu/compiler.h @@ -89,12 +89,11 @@ #define caa_is_signed_type(type) ((type) -1 < (type) 0) /* - * Sign-extend to long if needed, and output type is unsigned long. + * Cast to unsigned long, sign-extending if @v is signed. + * Note: casting to a larger type or to same type size keeps the sign of + * the expression being cast (see C99 6.3.1.3). */ -#define caa_cast_long_keep_sign(v) \ - (caa_is_signed_type(__typeof__(v)) ? \ - (unsigned long) (long) (v) : \ - (unsigned long) (v)) +#define caa_cast_long_keep_sign(v) ((unsigned long) (v)) #if defined (__GNUC__) \ && ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 5) \ -- 2.34.1