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Avoid cycles from projection bounds

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Only check the own predicates of associated types when confirming
projection candidates.
Also consider implied bounds when comparing trait and impl methods.
This commit is contained in:
Matthew Jasper 2020-07-25 13:41:53 +01:00
parent 596d6c4b3b
commit 0dfa6ff3be
11 changed files with 122 additions and 85 deletions
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36
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
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@ -157,22 +157,26 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
);
}),
);
// Require that the projection is well-formed.
let self_ty = self.infcx.replace_bound_vars_with_placeholders(&bound_self_ty);
let self_ty = normalize_with_depth_to(
self,
obligation.param_env,
obligation.cause.clone(),
obligation.recursion_depth + 1,
&self_ty,
&mut obligations,
);
obligations.push(Obligation::with_depth(
obligation.cause.clone(),
obligation.recursion_depth + 1,
obligation.param_env,
ty::PredicateKind::WellFormed(self_ty.into()).to_predicate(tcx),
));
if let ty::Projection(..) = bound_self_ty.skip_binder().kind {
for predicate in tcx.predicates_of(def_id).instantiate_own(tcx, substs).predicates {
let normalized = normalize_with_depth_to(
self,
obligation.param_env,
obligation.cause.clone(),
obligation.recursion_depth + 1,
&predicate,
&mut obligations,
);
obligations.push(Obligation::with_depth(
obligation.cause.clone(),
obligation.recursion_depth + 1,
obligation.param_env,
normalized,
));
}
}
obligations
})
}