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Rollup merge of #115294 - compiler-errors:cycle-err, r=oli-obk

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More precisely detect cycle errors from type_of on opaque

Not sure if this still needs work. Just putting it up for initial impressions, since it seems that a few people are frustrated with the increased error verbosity due to #113320.

Essentially we introduce a new sub-query for `type_of` specifically for opaques which returns a value that is able to distinguish "has errors" from "due to cycle recovery".

Fixes #115188

r? `@oli-obk`
This commit is contained in:
Matthias Krüger 2023-08-28 19:53:56 +02:00 • committed by GitHub
commit b4c63f06e8
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26 changed files with 297 additions and 309 deletions
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11
compiler/rustc_trait_selection/src/traits/select/mod.rs
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@ -2346,14 +2346,15 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
}
ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
let ty = self.tcx().type_of(def_id);
if ty.skip_binder().references_error() {
return Err(SelectionError::OpaqueTypeAutoTraitLeakageUnknown(def_id));
}
// We can resolve the `impl Trait` to its concrete type,
// which enforces a DAG between the functions requiring
// the auto trait bounds in question.
t.rebind(vec![ty.instantiate(self.tcx(), args)])
match self.tcx().type_of_opaque(def_id) {
Ok(ty) => t.rebind(vec![ty.instantiate(self.tcx(), args)]),
Err(_) => {
return Err(SelectionError::OpaqueTypeAutoTraitLeakageUnknown(def_id));
}
}
}
})
}