system.h (helper_const_non_const_cast): New inline for gcc version <= 4.0.

2010-06-11  Kai Tietz  <kai.tietz@onevision.com>

        * system.h (helper_const_non_const_cast): New inline for
        gcc version <= 4.0.
        (CONST_CAST2): For gcc version <= 4.0 use
        new helper to do const/non-const casting.

From-SVN: r160598

gcc/ChangeLog

+2010-06-11  Kai Tietz  <kai.tietz@onevision.com>
+
+	* system.h (helper_const_non_const_cast): New inline for
+	gcc version <= 4.0.
+	(CONST_CAST2): For gcc version <= 4.0 use
+	new helper to do const/non-const casting.
+
 2010-06-10  Richard Sandiford  <rdsandiford@googlemail.com>
 
 	* doc/md.texi: Document the "unspec" and "unspecv" enum names.

gcc/system.h

@@ -834,6 +834,20 @@ extern void fancy_abort (const char *, int, const char *) ATTRIBUTE_NORETURN;
 /* GCC 4.0.x has a bug where it may ICE on this expression,
    so does GCC 3.4.x (PR17436).  */
 #define CONST_CAST2(TOTYPE,FROMTYPE,X) ((__extension__(union {FROMTYPE _q; TOTYPE _nq;})(X))._nq)
+#elif defined(__GNUC__)
+static inline char *
+helper_const_non_const_cast (const char *p)
+{
+  union {
+    const char *const_c;
+    char *c;
+  } val;
+  val.const_c = p;
+  return val.c;
+}
+
+#define CONST_CAST2(TOTYPE,FROMTYPE,X) \
+	((TOTYPE) helper_const_non_const_cast ((const char *) (FROMTYPE) (X)))
 #else
 #define CONST_CAST2(TOTYPE,FROMTYPE,X) ((TOTYPE)(FROMTYPE)(X))
 #endif