commit 29226f39ae027e4252f9bf11906eb4eaa5fb6824
author Josh Gao <jmgao@google.com> Tue Apr 26 14:42:55 2016 -0700
committer Josh Gao <jmgao@google.com> Wed Apr 27 16:50:54 2016 -0700
tree 97cdbf287632aacf0648fac3a2475db0a1fb4887
parent c194fd30c6fa3537d918939dd0a762786f21d764

Tag unavailable functions with macro.

Add an __UNAVAILABLE macro, and use it for several functions which lack
implementations, but need to have visible declarations to be reexported
in the C++ standard library.

Bug: http://b/28178111
Change-Id: Ia4ae0207bbfcb7baa61821f0ef946257b019c0db

libc/include/sys/cdefs.h

diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index 2bd058e..b0e7b76 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -454,11 +454,13 @@
 #define __INTRODUCED_IN(api_level) __AVAILABILITY(introduced=api_level)
 #define __DEPRECATED_IN(api_level) __AVAILABILITY(deprecated=api_level)
 #define __REMOVED_IN(api_level) __AVAILABILITY(obsoleted=api_level)
+#define __UNAVAILABLE __attribute__((unavailable))
 #else
 #define __AVAILABILITY(...)
 #define __INTRODUCED_IN(api_level)
 #define __DEPRECATED_IN(api_level)
 #define __REMOVED_IN(api_level)
+#define __UNAVAILABLE __attribute__((__error__("unavailable")))
 #endif // __clang__
 
 #if __has_builtin(__builtin_umul_overflow) || __GNUC__ >= 5