Let Vec be used as an argument in fluent strings

[mejrs]

An alternative approach would be to have some kind of #[list] attribute for the derive macro to use, or a newtype for doing this. I chose the current approach because it's what people will try first and it'd be nice to have it "Just Work" - there's no need to write or read documentation.

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[rustbot]

rustc_error_messages was changed

cc @davidtwco, @compiler-errors, @JohnTitor, @estebank, @TaKO8Ki

[Noratrieb]

I think @Manishearth wanted to use ICU4X for this IIRC

[mejrs]

I think @Manishearth wanted to use ICU4X for this IIRC

This uses the list support added in #104047 . Other than the "x more" part, which I couldn't figure out - is that even supported?

[Manishearth]

This shouldn't be done this way: to handle "or more" you should be having the logic in the fluent file, something like

mir_build_uncovered = {$truncated ->
        [true] {$witnesses}
        *[other] {$witnesses}, and more
    } not covered

and the truncation logic being handled in Rust. Except that's not so straightforward since the list will already format with a , and. You might need to define a fluent custom function that is able to do list formatting, cc @davidtwco. Unfortunatley it doesn't have a list type yet.

Furthermore, not all lists will want to be truncated. We should have a TruncatedDiagnosticList type that has all this logic.

This would be easier if Fluent had builtin list formatting support (projectfluent/fluent#79)

---

I think the way to do this for now is have another internal list type (perhaps we can merge it all into StrList, which has And/Or and truncate/don't truncate options), and have it pull from a list_more = and {$count} more Fluent key that's "global"

[mejrs]

Thanks, I've just created a new type for it.

and have it pull from a list_more = and {$count} more Fluent key that's "global"

Where should this live?

[davidtwco]

Where should this live?

We could create a common.ftl for it?

[mejrs]

I'm not sure how to make it fit together though. I assume I'd need to get access to the bundle inside the IntoDiagnosticArg impl, but that doesn't seem quite right. Is my approach wrong?

[davidtwco]

I'm not sure how to make it fit together though. I assume I'd need to get access to the bundle inside the IntoDiagnosticArg impl, but that doesn't seem quite right. Is my approach wrong?

Is it possible with the way we use IntoDiagnosticArg that you could give it a reference to the Handler and use eager_translate?