@ctfeonly

[Nicholas Wilson]

On Friday, 8 December 2017 at 01:30:13 UTC, Manu wrote:
> I tried this, and was surprised it didn't work:
>
> int ctfeOnly(int x)
> {
> static assert(__ctfe);
> return x + 1;
> }
>
> This would probably solve the problem in a satisfying way 
> without an attribute?

I think that's because __ctfe, despite being magic, is actually a 
regular variable.

While this looks not too inelegant for a user perspective, I dont 
know how to handle this from a compiler perspective: filtering by 
attribute is as easy as "does this function have a UDA ctfeonly? 
If so, don't code generate it. Generating errors at codegen time 
is also trivial: when generating a call check to see if the 
callee is @ctfeonly, if it is give an error message

I don't know how to do that for a `static assert(__ctfe);`. That 
would require changes and semantic analysis in the front end 
which I am much less familiar with.