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don't mutably borrow inner infcx in all of ConstInferUnifier::consts

This commit is contained in:
b-naber 2021-10-29 12:32:06 +02:00
parent 4e0d3973fa
commit 04cb19692c
1 changed files with 20 additions and 9 deletions
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29
compiler/rustc_infer/src/infer/combine.rs
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@ -866,6 +866,7 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
Ok(a.rebind(self.relate(a.skip_binder(), b.skip_binder())?))
}
#[tracing::instrument(level = "debug", skip(self))]
fn tys(&mut self, t: Ty<'tcx>, _t: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
debug_assert_eq!(t, _t);
debug!("ConstInferUnifier: t={:?}", t);
@ -941,6 +942,7 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
}
}
#[tracing::instrument(level = "debug", skip(self))]
fn consts(
&mut self,
c: &'tcx ty::Const<'tcx>,
@ -951,29 +953,38 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
match c.val {
ty::ConstKind::Infer(InferConst::Var(vid)) => {
let mut inner = self.infcx.inner.borrow_mut();
let variable_table = &mut inner.const_unification_table();
// Check if the current unification would end up
// unifying `target_vid` with a const which contains
// an inference variable which is unioned with `target_vid`.
//
// Not doing so can easily result in stack overflows.
if variable_table.unioned(self.target_vid, vid) {
if self
.infcx
.inner
.borrow_mut()
.const_unification_table()
.unioned(self.target_vid, vid)
{
return Err(TypeError::CyclicConst(c));
}
let var_value = variable_table.probe_value(vid);
let var_value =
self.infcx.inner.borrow_mut().const_unification_table().probe_value(vid);
match var_value.val {
ConstVariableValue::Known { value: u } => self.consts(u, u),
ConstVariableValue::Unknown { universe } => {
if self.for_universe.can_name(universe) {
Ok(c)
} else {
let new_var_id = variable_table.new_key(ConstVarValue {
origin: var_value.origin,
val: ConstVariableValue::Unknown { universe: self.for_universe },
});
let new_var_id =
self.infcx.inner.borrow_mut().const_unification_table().new_key(
ConstVarValue {
origin: var_value.origin,
val: ConstVariableValue::Unknown {
universe: self.for_universe,
},
},
);
Ok(self.tcx().mk_const_var(new_var_id, c.ty))
}
}