Fix: silence gcc -Wextra warning

[urcu.git] / urcu / compiler.h

diff --git a/urcu/compiler.h b/urcu/compiler.h
index 19534f08522ac3cc28a3557d93f7a16baab6e56e..4b3185529bd886a0de8d906d465712a28ebb470c 100644 (file)
--- a/urcu/compiler.h
+++ b/urcu/compiler.h
@@ -89,16 +89,15 @@
 #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_MAJOR__ == 4) && (__GNUC_MINOR__ >= 5)      \
-               || __GNUC_MAJOR__ >= 5)
+       && ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 5)    \
+               || __GNUC__ >= 5)
 #define CDS_DEPRECATED(msg)    \
        __attribute__((deprecated(msg)))
 #else
@@ -108,4 +107,23 @@
 
 #define CAA_ARRAY_SIZE(x)      (sizeof(x) / sizeof((x)[0]))
 
+/*
+ * Don't allow compiling with buggy compiler.
+ */
+
+#ifdef __GNUC__
+# define URCU_GCC_VERSION      (__GNUC__ * 10000 \
+                               + __GNUC_MINOR__ * 100 \
+                               + __GNUC_PATCHLEVEL__)
+
+/*
+ * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58854
+ */
+# ifdef __ARMEL__
+#  if URCU_GCC_VERSION >= 40800 && URCU_GCC_VERSION <= 40802
+#   error Your gcc version produces clobbered frame accesses
+#  endif
+# endif
+#endif
+
 #endif /* _URCU_COMPILER_H */