Supported by both gcc and clang, so portable enough for most people. I also like glib's cleanup attribute wrappers: https://docs.gtk.org/glib/auto-cleanup.html.

It is non portable, that's true. But defer [1] is at least undergoing discussions w/the standard committee. Didn't make it into C23 but maybe next time.

[1] https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2895.htm