bjoernager/rust
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internally change regions to be covariant

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This commit is contained in:
Ali MJ Al-Nasrawy 2023-01-27 02:23:08 +03:00
parent c62665e09c
commit 381187dc76
18 changed files with 43 additions and 52 deletions
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8
compiler/rustc_hir_analysis/src/variance/constraints.rs
View file

@ -221,8 +221,7 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
}
ty::Ref(region, ty, mutbl) => {
let contra = self.contravariant(variance);
self.add_constraints_from_region(current, region, contra);
self.add_constraints_from_region(current, region, variance);
self.add_constraints_from_mt(current, &ty::TypeAndMut { ty, mutbl }, variance);
}
@ -254,9 +253,8 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
}
ty::Dynamic(data, r, _) => {
// The type `Foo<T+'a>` is contravariant w/r/t `'a`:
let contra = self.contravariant(variance);
self.add_constraints_from_region(current, r, contra);
// The type `Foo<T + 'a>` is covariant w/r/t `'a`:
self.add_constraints_from_region(current, r, variance);
if let Some(poly_trait_ref) = data.principal() {
self.add_constraints_from_invariant_substs(

3
compiler/rustc_infer/src/infer/glb.rs
View file

@ -79,7 +79,8 @@ impl<'tcx> TypeRelation<'tcx> for Glb<'_, '_, 'tcx> {
debug!("{}.regions({:?}, {:?})", self.tag(), a, b);
let origin = Subtype(Box::new(self.fields.trace.clone()));
Ok(self.fields.infcx.inner.borrow_mut().unwrap_region_constraints().glb_regions(
// GLB(&'static u8, &'a u8) == &RegionLUB('static, 'a) u8 == &'static u8
Ok(self.fields.infcx.inner.borrow_mut().unwrap_region_constraints().lub_regions(
self.tcx(),
origin,
a,

3
compiler/rustc_infer/src/infer/lub.rs
View file

@ -79,7 +79,8 @@ impl<'tcx> TypeRelation<'tcx> for Lub<'_, '_, 'tcx> {
debug!("{}.regions({:?}, {:?})", self.tag(), a, b);
let origin = Subtype(Box::new(self.fields.trace.clone()));
Ok(self.fields.infcx.inner.borrow_mut().unwrap_region_constraints().lub_regions(
// LUB(&'static u8, &'a u8) == &RegionGLB('static, 'a) u8 == &'a u8
Ok(self.fields.infcx.inner.borrow_mut().unwrap_region_constraints().glb_regions(
self.tcx(),
origin,
a,

8
compiler/rustc_infer/src/infer/nll_relate/mod.rs
View file

@ -663,13 +663,13 @@ where
debug!(?v_b);
if self.ambient_covariance() {
// Covariance: a <= b. Hence, `b: a`.
self.push_outlives(v_b, v_a, self.ambient_variance_info);
// Covariant: &'a u8 <: &'b u8. Hence, `'a: 'b`.
self.push_outlives(v_a, v_b, self.ambient_variance_info);
}
if self.ambient_contravariance() {
// Contravariant: b <= a. Hence, `a: b`.
self.push_outlives(v_a, v_b, self.ambient_variance_info);
// Contravariant: &'b u8 <: &'a u8. Hence, `'b: 'a`.
self.push_outlives(v_b, v_a, self.ambient_variance_info);
}
Ok(a)

3
compiler/rustc_infer/src/infer/sub.rs
View file

@ -191,12 +191,13 @@ impl<'tcx> TypeRelation<'tcx> for Sub<'_, '_, 'tcx> {
// from the "cause" field, we could perhaps give more tailored
// error messages.
let origin = SubregionOrigin::Subtype(Box::new(self.fields.trace.clone()));
// Subtype(&'a u8, &'b u8) => Outlives('a: 'b) => SubRegion('b, 'a)
self.fields
.infcx
.inner
.borrow_mut()
.unwrap_region_constraints()
.make_subregion(origin, a, b);
.make_subregion(origin, b, a);
Ok(a)
}

14
compiler/rustc_middle/src/ty/relate.rs
View file

@ -443,12 +443,7 @@ pub fn super_relate_tys<'tcx, R: TypeRelation<'tcx>>(
if a_repr == b_repr =>
{
let region_bound = relation.with_cause(Cause::ExistentialRegionBound, |relation| {
relation.relate_with_variance(
ty::Contravariant,
ty::VarianceDiagInfo::default(),
a_region,
b_region,
)
relation.relate(a_region, b_region)
})?;
Ok(tcx.mk_dynamic(relation.relate(a_obj, b_obj)?, region_bound, a_repr))
}
@ -487,12 +482,7 @@ pub fn super_relate_tys<'tcx, R: TypeRelation<'tcx>>(
}
(&ty::Ref(a_r, a_ty, a_mutbl), &ty::Ref(b_r, b_ty, b_mutbl)) => {
let r = relation.relate_with_variance(
ty::Contravariant,
ty::VarianceDiagInfo::default(),
a_r,
b_r,
)?;
let r = relation.relate(a_r, b_r)?;
let a_mt = ty::TypeAndMut { ty: a_ty, mutbl: a_mutbl };
let b_mt = ty::TypeAndMut { ty: b_ty, mutbl: b_mutbl };
let mt = relate_type_and_mut(relation, a_mt, b_mt, a)?;