RFE: cases from range expression

[hdonnay]

I'd like to be able to use syntax like

#[rstest]
#[case(0..256)]
fn testfunc(#[case] n: usize) {
    todo!()
}

I don't think there's another way to get a big list of tests like this, besides a lot of #[case(n)] lines or a long, written out #[values(...)] attribute.

[la10736]

Sorry but there isn't any way to get them instead of write them. Ok I can imagine that the procedural macro interpreter this as a script and generate them but that means I should implement a runtime in the procedural macro.

Another possibility is to define a language/syntax to accept them but I'm not incline to this kind of solutions.

[hdonnay]

I was thinking the macro could recognize a std::ops::Range and then manually do an equivalent counting loop, but that's undeniably fiddly.

[la10736]

It can just recognize the syntax and not the type. On procedural macro execution time we can have Just the syntax tree... Type resolution stage is executed later and procedural macro cannot leverage on it