Right. One is what the C standard says, and the other is what the ABI standard says. Maybe I’m missing something here.

Obviously, when someone says “type X is size Y on architecture Z”, they’re not talking about the C standard, they’re talking about some particular ABI.

> the other is what the ABI standard says

There are multiple ABIs for x86_64. I think the major compilers use 32 bits for int and 64 for long, but there could very well be a compiler that used different sizes, with a different ABI.

Yep, the x32 ABI on Linux is based on the amd64 instruction set, registers, etc. but uses 32-bit long and pointers (which in my experience is a nice performance boost, I measured up to 20% in some cases)