[Bug c/90293] New function attribute: expect_return

[bugzi...@poradnik-webmastera.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90293

--- Comment #1 from Daniel Fruzynski <bugzi...@poradnik-webmastera.com> ---
One more case: sometimes it may be more handy to specify what will *not* be
usually returned, e.g. special invalid value. For such cases another attribute
would be needed:

__attribute__((expect_not_return(-1)))
int CreateSocket();