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Rollup merge of #109462 - compiler-errors:alias-relate, r=BoxyUwU,lcnr

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Make alias-eq have a relation direction (and rename it to alias-relate)

Emitting an "alias-eq" is too strict in some situations, since we don't always want strict equality between a projection and rigid ty. Adds a relation direction.

* I could probably just reuse this [`RelationDir`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_infer/infer/combine/enum.RelationDir.html) -- happy to uplift that struct into middle and use that instead, but I didn't feel compelled to... 🤷
* Some of the matching in `compute_alias_relate_goal` is a bit verbose -- I guess I could simplify it by using [`At::relate`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_infer/infer/at/struct.At.html#method.relate) and mapping the relation-dir to a variance.
* Alternatively, I coulld simplify things by making more helper functions on `EvalCtxt` (e.g. `EvalCtxt::relate_with_direction(T, T)` that also does the nested goal registration). No preference.

r? ```@lcnr``` cc ```@BoxyUwU``` though boxy can claim it if she wants
NOTE: first commit is all the changes, the second is just renaming stuff
This commit is contained in:
Matthias Krüger 2023-03-23 08:35:35 +01:00 • committed by GitHub
commit 5d28853efe
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36 changed files with 259 additions and 98 deletions
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2
compiler/rustc_hir_analysis/src/astconv/mod.rs
View file

@ -1335,7 +1335,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
ty::Clause::RegionOutlives(_) | ty::Clause::ConstArgHasType(..) => bug!(),
},
ty::PredicateKind::WellFormed(_)
| ty::PredicateKind::AliasEq(..)
| ty::PredicateKind::AliasRelate(..)
| ty::PredicateKind::ObjectSafe(_)
| ty::PredicateKind::ClosureKind(_, _, _)
| ty::PredicateKind::Subtype(_)

2
compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs
View file

@ -528,7 +528,7 @@ fn trait_predicate_kind<'tcx>(
| ty::PredicateKind::Clause(ty::Clause::TypeOutlives(_))
| ty::PredicateKind::Clause(ty::Clause::Projection(_))
| ty::PredicateKind::Clause(ty::Clause::ConstArgHasType(..))
| ty::PredicateKind::AliasEq(..)
| ty::PredicateKind::AliasRelate(..)
| ty::PredicateKind::WellFormed(_)
| ty::PredicateKind::Subtype(_)
| ty::PredicateKind::Coerce(_)

2
compiler/rustc_hir_analysis/src/outlives/explicit.rs
View file

@ -56,7 +56,7 @@ impl<'tcx> ExplicitPredicatesMap<'tcx> {
| ty::PredicateKind::Clause(ty::Clause::Projection(..))
| ty::PredicateKind::Clause(ty::Clause::ConstArgHasType(..))
| ty::PredicateKind::WellFormed(..)
| ty::PredicateKind::AliasEq(..)
| ty::PredicateKind::AliasRelate(..)
| ty::PredicateKind::ObjectSafe(..)
| ty::PredicateKind::ClosureKind(..)
| ty::PredicateKind::Subtype(..)