Fix: silence gcc -Wextra warning
authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fri, 24 Oct 2014 21:13:39 +0000 (17:13 -0400)
committerMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fri, 24 Oct 2014 21:15:31 +0000 (17:15 -0400)
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 <mathieu.desnoyers@efficios.com>
urcu/compiler.h

index 2e0237e15194d01953fa8d5792c9194acb270a08..4b3185529bd886a0de8d906d465712a28ebb470c 100644 (file)
 #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)    \
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