use some fancy compiler magic (thanks to Matthew Woehlke on the gcc-help mailing list) to restore type-safety to S_OR by going back to a macro, but preserve the side-effect-safe usage of the macro arguments

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@155967 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/strings.h

@@ -52,19 +52,13 @@ static force_inline int ast_strlen_zero(const char *s)
 /*! \brief returns the equivalent of logic or for strings:
  * first one if not empty, otherwise second one.
  */
-static force_inline char *S_OR(const char *a, const char *b)
-{
-	return ast_strlen_zero(a) ? (char *) b : (char *) a;
-}
+#define S_OR(a, b) ({typeof(&((a)[0])) __x = (a); ast_strlen_zero(__x) ? (b) : __x;})
 
 /*! \brief returns the equivalent of logic or for strings, with an additional boolean check:
  * second one if not empty and first one is true, otherwise third one.
  * example: S_COR(usewidget, widget, "<no widget>")
  */
-static force_inline char *S_COR(unsigned char a, const char *b, const char *c)
-{
-	return a && !ast_strlen_zero(b) ? (char *) b : (char *) c;
-}
+#define S_COR(a, b, c) ({typeof(&((b)[0])) __x = (b); (a) && !ast_strlen_zero(__x) ? (__x) : (c);})
 
 /*!
   \brief Gets a pointer to the first non-whitespace character in a string.