Integer precision of function return types

[user1234]

On Thursday, 26 September 2024 at 06:53:12 UTC, Per Nordlöw wrote:
> Should a function like
>
> ```d
> uint parseHex(in char ch) pure nothrow @safe @nogc {
> 	switch (ch) {
> 	case '0': .. case '9':
> 		return ch - '0';
> 	case 'a': .. case 'f':
> 		return 10 + ch - 'a';
> 	case 'A': .. case 'F':
> 		return 10 + ch - 'A';
> 	default:
> 		assert(0, "Non-hexadecimal character");
> 	}
> }
> ```
>
> instead return an ubyte?

I have no conclusive answer:

- From an ABI PoV that does not matter, it's AL vs EAX , i.e same 
"parent" register.
- From a self-documenting PoV I'd use ubyte. But then you hit the 
problem of promotion of `ch - ...` and you have to cast each of 
them.