ICE when missing $ in front of a fluent variable

[oli-obk]

I tried this code:

the_slug =
    foo bar {boo} beep bop

I expected to see this happen: an error telling me {boo} needs to be {$boo}

Instead, this happened:

thread 'rustc' panicked at 'identifier: "hir_analysis_const_impl_for_non_const_trait", attr: Some("suggestion"), args: FluentArgs([("trait_name", String("A"))]), errors: [ResolverError(Reference(Message { id: "trait_name", attribute: None }))]', compiler/rustc_errors/src/translation.rs:105:17

[davidtwco]

The issue here is that this isn't a Fluent error, we'd get a nice diagnostic if it was, it is still valid Fluent which refers to another slug, boo, which we only find out about when actually trying to do a translation. Everything is written so that if this mistake happens in a non-default locale, then we'll fallback to English and have a good user experience. But if it happens in the default locale, then we just expect tests to catch it. We could probably walk the AST of the parsed Fluent in the fluent_messages macro and try catch it then.

[oli-obk]

Yea... I think if we could just improve the ICE that would be sufficient.