[Bug c/66425] (void) cast doesn't suppress __attribute__((warn_unused_result))

[jengelh at inai dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425

--- Comment #20 from Jan Engelhardt <jengelh at inai dot de> ---
Seems like the short route is to add a new attribute
((warn_unused_result_with_void_cancelling)) that exhibits the "desired"
behavior of (void) cancelling the warning, and then make glibc use that.
Simple, no?