Add __attribute__((unused)) to __BIONIC_ERROR_FUNCTION_VISIBILITY
This commit adds `__attribute__((unused))` to
`__BIONIC_ERROR_FUNCTION_VISIBILITY`, so that `open()`, `openat()`,
`snprintf()`, and `sprintf()` don't raise `-Werror,-Wunused-function`
when `_FORTIFY_SOURCE` is enabled.
These errors were hidden because the include directories were passed
with `-isystem` (instead of `-I`) and clang did not report
`-Wunused-function` from `-isystem`.
Bug: 119086738
Test: make checkbuild
Change-Id: I0de71efdbacd90c5c6a419fc0368c92e8efdfd63
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index e9d0e4b..a919a79 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -280,7 +280,7 @@
*/
# define __BIONIC_FORTIFY_VARIADIC static __inline__
/* Error functions don't have bodies, so they can just be static. */
-# define __BIONIC_ERROR_FUNCTION_VISIBILITY static
+# define __BIONIC_ERROR_FUNCTION_VISIBILITY static __attribute__((unused))
#else
/* Further increase sharing for some inline functions */
# define __pass_object_size_n(n)