Nice, if this is reliable across gcc versions and optimization levels, I might consider it for future stuff. Though making it such that treesitter and other tools dont barf on it would still need investigation.
It's unfortunate a lot of the standards guys are horrified by anything that isn't C89. Because if the executable stack is an issue it's worth fixing.
Side note: 20 years ago people thought if they made the stack non executable that would totally fix stack smashing attacks and unfortunately it only slows down script kiddies.
Slowing them down is good. And: separating data and code helps simplify managing the caches.