bjoernager/rust
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Do not leak type variables from opaque type relation

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This commit is contained in:
Michael Goulet 2022-07-30 00:41:39 +00:00
parent 9de7474830
commit fb12f40f3b
3 changed files with 48 additions and 3 deletions
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17
compiler/rustc_infer/src/infer/sub.rs
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@ -4,6 +4,7 @@ use super::SubregionOrigin;
use crate::infer::combine::ConstEquateRelation;
use crate::infer::{TypeVariableOrigin, TypeVariableOriginKind};
use crate::traits::Obligation;
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::relate::{Cause, Relate, RelateResult, TypeRelation};
use rustc_middle::ty::visit::TypeVisitable;
use rustc_middle::ty::TyVar;
@ -141,17 +142,27 @@ impl<'tcx> TypeRelation<'tcx> for Sub<'_, '_, 'tcx> {
Ok(infcx.tcx.mk_ty_var(var))
};
let (a, b) = if self.a_is_expected { (a, b) } else { (b, a) };
let (a, b) = match (a.kind(), b.kind()) {
let (ga, gb) = match (a.kind(), b.kind()) {
(&ty::Opaque(..), _) => (a, generalize(b, true)?),
(_, &ty::Opaque(..)) => (generalize(a, false)?, b),
_ => unreachable!(),
};
self.fields.obligations.extend(
infcx
.handle_opaque_type(a, b, true, &self.fields.trace.cause, self.param_env())?
.handle_opaque_type(ga, gb, true, &self.fields.trace.cause, self.param_env())
// Don't leak any generalized type variables out of this
// subtyping relation in the case of a type error.
.map_err(|err| {
let (ga, gb) = self.fields.infcx.resolve_vars_if_possible((ga, gb));
if let TypeError::Sorts(sorts) = err && sorts.expected == ga && sorts.found == gb {
TypeError::Sorts(ExpectedFound { expected: a, found: b })
} else {
err
}
})?
.obligations,
);
Ok(a)
Ok(ga)
}
_ => {