-Wabsolutely-everything

I haven't written the Language of Kings in a while: does GCC -Wall truly enable all warnings yet?

It doesn't, and that would be a bad thing, because warnings aren't magic and bug-free themselves. Nor is there any reason to comply with every single warning every person in the world has come up with.

clang has a -Weverything and it isn't supported.

Obviously not. It would be an instant scandal if they tried that.