file.c: fix compile error with MacPorts gcc

With the SDK of Xcode 10.2.1, `API_AVAILABLE` and so on macros are
not defined in <os/availability.h> when using a compiler other
than clang (which has `__has_feature` and `__has_attribute`), but
`__API_AVAILABLE` macro and so on are defined, which are also
defined in <Availability.h>.

I suspect this is a bug of the SDK.

1 files changed, 8 insertions, 0 deletions

diff --git a/file.c b/file.c
index a04fe538e5..3da358af1f 100644
--- a/file.c
+++ b/file.c
@@ -20,6 +20,14 @@
 #include <wchar.h>
 #endif
 #ifdef __APPLE__
+# if !(defined(__has_feature) && defined(__has_attribute))
+/* Maybe a bug in SDK of Xcode 10.2.1 */
+/* In this condition, <os/availability.h> does not define
+ * API_AVAILABLE and similar, but __API_AVAILABLE and similar which
+ * are defined in <Availability.h> */
+#   define API_AVAILABLE(...)
+#   define API_DEPRECATED(...)
+# endif
 #include <CoreFoundation/CFString.h>
 #endif