That’s not an argument; every major C compiler recognizes include guards, and every standards compliment C compiler supports them. The whole point of #pragma on

That’s not an argument; every major C compiler recognizes include guards, and every standards compliment C compiler supports them. The whole point of #pragma once is so you don’t have to use them and worry if you have naming collisions. The issue is that gcc uses a horribly performant method of handling #pragma once when it’s nothing more than a fancy include guard. Clearly they have some quick and optimized way of seeing if a file was #ifdef include guarded, but they created a whole other system based on linked lists for #pragma once.