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Remove unneeded sub-comparison

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This commit is contained in:
Oli Scherer 2022-10-19 15:49:08 +00:00
parent f3bd222ad9
commit de5517c3ae
1 changed files with 8 additions and 31 deletions
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39
compiler/rustc_infer/src/infer/sub.rs
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@ -2,9 +2,7 @@
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;
@ -130,39 +128,18 @@ fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
(&ty::Opaque(did, ..), _) | (_, &ty::Opaque(did, ..))
if self.fields.define_opaque_types && did.is_local() =>
{
let mut generalize = |ty, ty_is_expected| {
let var = infcx.next_ty_var_id_in_universe(
TypeVariableOrigin {
kind: TypeVariableOriginKind::MiscVariable,
span: self.fields.trace.cause.span,
},
ty::UniverseIndex::ROOT,
);
self.fields.instantiate(ty, RelationDir::SubtypeOf, var, ty_is_expected)?;
Ok(infcx.tcx.mk_ty_var(var))
};
let (a, b) = if self.a_is_expected { (a, b) } else { (b, a) };
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(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
}
})?
.handle_opaque_type(
a,
b,
self.a_is_expected,
&self.fields.trace.cause,
self.param_env(),
)?
.obligations,
);
Ok(ga)
Ok(a)
}
// Optimization of GeneratorWitness relation since we know that all
// free regions are replaced with bound regions during construction.