[libdvdnav-devel] [PATCH] add __DEPRECATED__ modifier which can be used to deprecate API calls where compiler supports it

[Lawrence D'Oliveiro]

Rather than checking the GNUC version in the C code to see if it
supports __attribute__((deprecated)), this does the check at configure
time, to be compatible with non-GCC compilers that also support the
same language extension.

---
 configure.ac           | 6 ++++++
 src/dvdread/ifo_read.h | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/configure.ac b/configure.ac
index 9142673..6eb4c20 100644
--- a/configure.ac
+++ b/configure.ac
@@ -47,6 +47,12 @@ AC_SUBST([DVDREAD_LTVERSION], [$DVDREAD_LT_CURRENT:$DVDREAD_LT_REVISION:$DVDREAD
 
 AC_PROG_CC
 
+AC_COMPILE_IFELSE(
+    [AC_LANG_PROGRAM([__attribute__((deprecated)) extern void f(void);], [])],
+    [echo C compiler supports "__attribute__((deprecated))"; AC_DEFINE([HAVE_ATTRIBUTE_DEPRECATED], [1], [define to 1 if C compiler allows nested routines])],
+    [echo WARNING: C compiler does not support "__attribute__((deprecated))"]
+)
+
 AC_CHECK_HEADERS_ONCE([sys/param.h limits.h dlfcn.h])
 
 AC_SYS_LARGEFILE
diff --git a/src/dvdread/ifo_read.h b/src/dvdread/ifo_read.h
index 97f4179..8b58b61 100644
--- a/src/dvdread/ifo_read.h
+++ b/src/dvdread/ifo_read.h
@@ -25,6 +25,12 @@
 #include "ifo_types.h"
 #include "dvdread/dvd_reader.h"
 
+#if defined(HAVE_ATTRIBUTE_DEPRECATED)
+    #define __DEPRECATED__ __attribute__((deprecated))
+#else
+    #define __DEPRECATED__
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
-- 
2.1.0