Request for Comment assert(__ctfe)

[Timon Gehr]

On 05.04.20 14:11, Stefan Koch wrote:
> Hi Guys,
> 
> I am currently working on speeding up dmd. In the presence of templates 
> and ctfe.
> and one thing that stood out is that we do codegen for symbols which are 
> never used.
> (and hopefully eliminated by a smart linker but eh ...)
> 
> I've seen the following pattern in the wild.
> 
> 
> string GenerateMixin(string[] params)
> {
>      assert(__ctfe);
>      .... more code ....
> }
> 
> that means if we see assert(__ctfe) inside the outermost scope of a 
> function body ( not in a branch) then we know that this function would 
> assert if called at runtime.

Make sure it works with `in` contracts:

string generateMixin(string[] params)in{
     assert(__ctfe);
}do{
     .... more code ....
}

(The plain assertion slightly hurts my eyes, because if it fails, that 
failure would be attributable to the GenerateMixin function, whereas 
with the `in` contract it is clear that the caller is at fault.)