Allow Trait inheritance with cycles on associated types by spastorino · Pull Req...
source link: https://github.com/rust-lang/rust/pull/79209
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nikomatsakis left a comment
I thought I had some good creative ideas for tests but as I look at it, most of them are kind of the same as the tests you already have.
I guess I think we should test some scenarios that ARE still ambiguous, e.g.
trait Foo { type Item; }
trait Bar<T> { type Item; }
trait Baz: Foo + Bar<Self::Item> { }/// Ensures that the super-predicates of the trait with a `DefId`
/// of `trait_def_id` are converted and stored. This also ensures that
/// the transitive super-predicates are converted.
fn super_predicates_that_define_assoc_type(
nikomatsakis on Nov 20
Contributor
Hmm so this is a query... it's a bit unusual in that most query providers either operate on local def-ids or external def-ids but not both. (The typical strategy, in other words, would be to define this query by encoding it into the metadata.) But that seems kind of silly here, I don't see a reason to encode more into the metadata. So this setup is probably ok. But I feel like we have to be sure to setup the provider also for external crates or we will see ICEs -- I'm a bit surprised our tests aren't encountering them yet, actually.
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