In glib, I made g_string_free () warn on unused result, but only if the second argument is compile-time FALSE.
(If this breaks your build, you know whom to blame. No, not me. Yourself for enabling -Werror. 😀)
In glibc, I implemented O_TMPFILE (open anonymous temporary files!) and SHM_OPEN (open anonymous shared memory!), compatible with Linux and FreeBSD respectively.
Both got merged yesterday