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avoid instantiating infer vars with infer

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This commit is contained in:
lcnr 2023-12-07 16:13:09 +01:00
parent 7df0c211ac
commit 40aa9f4fd9
2 changed files with 9 additions and 4 deletions
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8
compiler/rustc_infer/src/infer/combine.rs
View file

@ -34,6 +34,7 @@ use rustc_middle::infer::unify_key::{ConstVarValue, ConstVariableValue, EffectVa
use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::relate::{RelateResult, TypeRelation};
use rustc_middle::ty::TyVar;
use rustc_middle::ty::{self, InferConst, ToPredicate, Ty, TyCtxt, TypeVisitableExt};
use rustc_middle::ty::{IntType, UintType};
use rustc_span::DUMMY_SP;
@ -459,7 +460,12 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
ambient_variance,
)?;
self.infcx.inner.borrow_mut().type_variables().instantiate(b_vid, b_ty);
// Constrain `b_vid` to the generalized type `b_ty`.
if let &ty::Infer(TyVar(b_ty_vid)) = b_ty.kind() {
self.infcx.inner.borrow_mut().type_variables().equate(b_vid, b_ty_vid);
} else {
self.infcx.inner.borrow_mut().type_variables().instantiate(b_vid, b_ty);
}
if needs_wf {
self.obligations.push(Obligation::new(

5
compiler/rustc_infer/src/infer/type_variable.rs
View file

@ -229,12 +229,11 @@ impl<'tcx> TypeVariableTable<'_, 'tcx> {
/// Precondition: `vid` must not have been previously instantiated.
pub fn instantiate(&mut self, vid: ty::TyVid, ty: Ty<'tcx>) {
let vid = self.root_var(vid);
debug_assert!(!ty.is_ty_var(), "instantiating ty var with var: {vid:?} {ty:?}");
debug_assert!(self.probe(vid).is_unknown());
debug_assert!(
self.eq_relations().probe_value(vid).is_unknown(),
"instantiating type variable `{:?}` twice: new-value = {:?}, old-value={:?}",
vid,
ty,
"instantiating type variable `{vid:?}` twice: new-value = {ty:?}, old-value={:?}",
self.eq_relations().probe_value(vid)
);
self.eq_relations().union_value(vid, TypeVariableValue::Known { value: ty });