Re: byteswap.h behavior

[Paul Eggert]

On 2024-05-12 12:47, Collin Funk wrote:
> Yeah, I read the POSIX draft and it says that they may be macros. I
> doubt the byteswap.h and endian.h functions are used with non-constant
> expression arguments that often.

I sense a bit of confusion here. Although POSIX allows <endian.h> 
symbols like be16toh to be macros, I don't see where it allows 
be16toh(X) to evaluate X more than once, so an expression like 
be16toh(i++) has well-defined behavior even though it has a side effect.

A few function-like macros, like getc, are explicitly allowed to 
evaluate their arguments more than once, but ordinarily function-like 
macros are supposed to act like their corresponding functions.