-Wall -Werror means that instead of being able to be used as a ratchet the set of "all" warnings in C and C++ became rusted in place. I sympathise with the instinct to write this in your compiler flags, but alas thanks to Hyrum's law this makes the future worse and so today people ask that you -Wextra and no doubt I'll eventually read of how C is fine so long as you -Wall -Wextra -Wevenmore -Wyetmore -Wandthese