[PATCH] libintl.h: Add format argument attributes to gettext function prototypes

[Khem Raj <raj.khem@gmail.com>]

compiling glib-2.0 clang errors out with

error: format string is not a string literal

when these functions are used, it can be enforced that the format
arguments to these gettext* functions  be string literals, so that the compiler knows that it
always will be string literals

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 include/libintl.h | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/include/libintl.h b/include/libintl.h
index a2dada6..6a707bf 100644
--- a/include/libintl.h
+++ b/include/libintl.h
@@ -8,16 +8,24 @@ extern "C" {
 #define __USE_GNU_GETTEXT 1
 #define __GNU_GETTEXT_SUPPORTED_REVISION(major) ((major) == 0 ? 1 : -1)
 
-char *gettext(const char *);
-char *dgettext(const char *, const char *);
-char *dcgettext(const char *, const char *, int);
-char *ngettext(const char *, const char *, unsigned long);
-char *dngettext(const char *, const char *, const char *, unsigned long);
-char *dcngettext(const char *, const char *, const char *, unsigned long, int);
+#if __GNUC__ >= 3
+#define __fa(n) __attribute__ ((__format_arg__ (n)))
+#else
+#define __fa(n)
+#endif
+
+char *gettext(const char *) __fa(1);
+char *dgettext(const char *, const char *) __fa(2);
+char *dcgettext(const char *, const char *, int) __fa(2);
+char *ngettext(const char *, const char *, unsigned long) __fa(1) __fa(2);
+char *dngettext(const char *, const char *, const char *, unsigned long) __fa(2) __fa(3);
+char *dcngettext(const char *, const char *, const char *, unsigned long, int) __fa(2) __fa(3);
 char *textdomain(const char *);
 char *bindtextdomain (const char *, const char *);
 char *bind_textdomain_codeset(const char *, const char *);
 
+#undef __fa
+
 #ifdef __cplusplus
 }
 #endif
-- 
2.5.2