To avoid the compiler complaining about the unused return value, by telling it I'm explicitly choosing to ignore the value.

The complaint doesn't show up on the default warning levels. I think only with -W ? (fun fact: -Wall actually has fewer warnings enabled than -W, at least with Clang)

Edit: actually, the warning is enabled by default, but only triggers for functions that have the attribute 'warn_unused_result' set, which is almost none of them, which is why this warning is not well-known. Indeed, in my example my (void) isn't necessary, and I couldn't get the warning to trigger even with -Wpedantic.