Integer promotion issue

[Shachar Shemesh]

On 26/01/2020 01:46, Evan wrote:
> I am writing an 8 bit emulator that uses a lot of small numbers and
> running into a problem where the compiler will automatically promote
> smaller operands up to an int which causes the result of math
> calculations to not fit into smaller types.
> 
> //compiled with dmd 2.090.0
> void main()
> {
>     ubyte a = 0x01;
>     ubyte b = 0x01;
>     ubyte c = a + b; //Error: cannot implicitly convert expression
> cast(int)a + cast(int)b of type int to ubyte
>     writeln(c);
> }
> 
> Is there a way to stop the compiler from up casting automatically? or
> have it down cast it back once it's done?

It was a recurring pet-peeve for me while working with D, and for pretty
much the same reason as you (for me it was writing the RAID algorithm
for Weka.io).

I have since decided to write my own programming language, and,
predictably, this was a problem I decided to tackle.

I am posting this here in the hope that someone will be able to steal
any good ideas I have. I am working on it, but I do so alone, and in my
spare time (such that there is). I would much rather have good ideas be
used than be given credit for them, but see them go unused.

So if there is anything you think is worth stealing, please do. I don't
think it is possible, as Practical's integer promotion rules are _very_
different, and I don't see retrofitting them as plausible, but on the
off chance I'm wrong:

https://github.com/Practical/practical-sa/wiki/Implicit-casts