That’s common though for variadic functions, particularly printf! Many printf implementations will blindly do a va_arg (popping the stack pointer by 4 or 8 byte

That’s common though for variadic functions, particularly printf! Many printf implementations will blindly do a va_arg (popping the stack pointer by 4 or 8 bytes) if the format string says so. If your call to printf looks like: printf(“%d %d %d %d”, x, y); then you’re going to “read” two more ints from the stack at the call site. clang (and later gcc, I think) thus have a semantic analysis pass that understands/parses printf-style formatting strings so it can tell “hey, you didn’t pass enough arguments” or just as frequently “you passed too few”.