Any reason why ++1 is not folded to a new constant?

[Walter Bright]

On 10/20/2020 5:41 AM, Basile B. wrote:
> I've reached a similar problem in another language and I wanted to see what is 
> the D policy. I've been surprised by the result. It seems that there's no 
> special case for compile-time-only values, eg this case of RValue:
> ---
> void main()
> {
>      writeln(++1); // NG: cannot modify constant `1`
> }
> ---
> 
> is there any reasons why ++1 is not optimized to 2 ?

Because ++ is supposed to operate on an lvalue, and `1` is an rvalue. `++1` is 
nonsense.

I don't see the point to adding a special case for it - special cases are warts 
and need strong justifications to add.