cast(function qualifier)

[Quirin Schroll]

On Thursday, 2 May 2024 at 07:46:48 UTC, Jonathan M Davis wrote:
> That being said, one concern that I can think of is that it 
> arguably makes
> cast() inconsistent. Right now, casting with an attribute only 
> works with
> type qualifiers, so it makes sense that cast() would remove all 
> type
> qualifiers. However, if stuff like cast(pure) or cast(nothrow) 
> is legal,
> then I could see someone expecting that cast() would remove 
> those as well,
> which seems like it would be a bad idea in practice (as well as 
> being a
> breaking change). But if we don't make cast() remove pure, 
> nothrow, etc.,
> then it could be argued that that's inconsistent. I'm not sure 
> that that
> inconsistency is worth worrying about, but I could see it 
> coming up at some
> point.

Another good argument to add `@gc` and `@impure`. Then, one can 
`cast(@gc)` to remove a `@nogc` attribute.

Another option would be to extend `cast` to allow for negated 
stuff: `cast(!const)` would remove `const`, but not other type 
qualifiers, e.g. `inout` or `shared`. In particular, 
`cast(!shared)` would be useful to remove `shared` whilst not 
touching `const` accidentally. Same would work for function 
attributes: `const(!pure)` removes `pure`, but doesn’t touch type 
qualifiers or other attributes.