From 3cb36317cdea5c4de0224f64a0ec6db5cd50a8fd Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 19 Feb 2024 20:36:17 +0000
Subject: [PATCH 1/7] Preserve variance on error in generalizer
---
compiler/rustc_infer/src/infer/relate/generalize.rs | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/compiler/rustc_infer/src/infer/relate/generalize.rs b/compiler/rustc_infer/src/infer/relate/generalize.rs
index e84d4ceaea8..b18c8a8b844 100644
--- a/compiler/rustc_infer/src/infer/relate/generalize.rs
+++ b/compiler/rustc_infer/src/infer/relate/generalize.rs
@@ -440,9 +440,9 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
debug!(?self.ambient_variance, "new ambient variance");
// Recursive calls to `relate` can overflow the stack. For example a deeper version of
// `ui/associated-consts/issue-93775.rs`.
- let r = ensure_sufficient_stack(|| self.relate(a, b))?;
+ let r = ensure_sufficient_stack(|| self.relate(a, b));
self.ambient_variance = old_ambient_variance;
- Ok(r)
+ r
}
#[instrument(level = "debug", skip(self, t2), ret)]
From c87b727a23cd1a04379770edbdc758538a8bc3d0 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Thu, 22 Feb 2024 17:18:35 +0000
Subject: [PATCH 2/7] Combine sub and eq
---
.../src/type_check/relate_tys.rs | 13 +-
.../rustc_infer/src/infer/relate/combine.rs | 30 +-
.../rustc_infer/src/infer/relate/equate.rs | 228 ------------
compiler/rustc_infer/src/infer/relate/glb.rs | 10 +-
compiler/rustc_infer/src/infer/relate/lub.rs | 10 +-
compiler/rustc_infer/src/infer/relate/mod.rs | 3 +-
compiler/rustc_infer/src/infer/relate/sub.rs | 229 ------------
.../src/infer/relate/type_relating.rs | 325 ++++++++++++++++++
8 files changed, 356 insertions(+), 492 deletions(-)
delete mode 100644 compiler/rustc_infer/src/infer/relate/equate.rs
delete mode 100644 compiler/rustc_infer/src/infer/relate/sub.rs
create mode 100644 compiler/rustc_infer/src/infer/relate/type_relating.rs
diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
index 85f63371659..fd6c29379a3 100644
--- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs
+++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
@@ -349,12 +349,15 @@ impl<'bccx, 'tcx> TypeRelation<'tcx> for NllTypeRelating<'_, 'bccx, 'tcx> {
debug!(?self.ambient_variance);
// In a bivariant context this always succeeds.
- let r =
- if self.ambient_variance == ty::Variance::Bivariant { a } else { self.relate(a, b)? };
+ let r = if self.ambient_variance == ty::Variance::Bivariant {
+ Ok(a)
+ } else {
+ self.relate(a, b)
+ };
self.ambient_variance = old_ambient_variance;
- Ok(r)
+ r
}
#[instrument(skip(self), level = "debug")]
@@ -579,10 +582,6 @@ impl<'bccx, 'tcx> ObligationEmittingRelation<'tcx> for NllTypeRelating<'_, 'bccx
);
}
- fn alias_relate_direction(&self) -> ty::AliasRelationDirection {
- unreachable!("manually overridden to handle ty::Variance::Contravariant ambient variance")
- }
-
fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
self.register_predicates([ty::Binder::dummy(match self.ambient_variance {
ty::Variance::Covariant => ty::PredicateKind::AliasRelate(
diff --git a/compiler/rustc_infer/src/infer/relate/combine.rs b/compiler/rustc_infer/src/infer/relate/combine.rs
index 0852bb4f993..0a550660f94 100644
--- a/compiler/rustc_infer/src/infer/relate/combine.rs
+++ b/compiler/rustc_infer/src/infer/relate/combine.rs
@@ -1,4 +1,6 @@
-//! There are four type combiners: [Equate], [Sub], [Lub], and [Glb].
+//! There are four type combiners: [TypeRelating], [Lub], and [Glb],
+//! and `NllTypeRelating` in rustc_borrowck, which is only used for NLL.
+//!
//! Each implements the trait [TypeRelation] and contains methods for
//! combining two instances of various things and yielding a new instance.
//! These combiner methods always yield a `Result<T>`. To relate two
@@ -22,10 +24,9 @@
//! [TypeRelation::a_is_expected], so when dealing with contravariance
//! this should be correctly updated.
-use super::equate::Equate;
use super::glb::Glb;
use super::lub::Lub;
-use super::sub::Sub;
+use super::type_relating::TypeRelating;
use super::StructurallyRelateAliases;
use crate::infer::{DefineOpaqueTypes, InferCtxt, TypeTrace};
use crate::traits::{Obligation, PredicateObligations};
@@ -322,12 +323,12 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
&'a mut self,
structurally_relate_aliases: StructurallyRelateAliases,
a_is_expected: bool,
- ) -> Equate<'a, 'infcx, 'tcx> {
- Equate::new(self, structurally_relate_aliases, a_is_expected)
+ ) -> TypeRelating<'a, 'infcx, 'tcx> {
+ TypeRelating::new(self, a_is_expected, structurally_relate_aliases, ty::Invariant)
}
- pub fn sub<'a>(&'a mut self, a_is_expected: bool) -> Sub<'a, 'infcx, 'tcx> {
- Sub::new(self, a_is_expected)
+ pub fn sub<'a>(&'a mut self, a_is_expected: bool) -> TypeRelating<'a, 'infcx, 'tcx> {
+ TypeRelating::new(self, a_is_expected, StructurallyRelateAliases::No, ty::Covariant)
}
pub fn lub<'a>(&'a mut self, a_is_expected: bool) -> Lub<'a, 'infcx, 'tcx> {
@@ -367,19 +368,8 @@ pub trait ObligationEmittingRelation<'tcx>: TypeRelation<'tcx> {
/// be used if control over the obligation causes is required.
fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ToPredicate<'tcx>>);
- /// Register an obligation that both types must be related to each other according to
- /// the [`ty::AliasRelationDirection`] given by [`ObligationEmittingRelation::alias_relate_direction`]
- fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
- self.register_predicates([ty::Binder::dummy(ty::PredicateKind::AliasRelate(
- a.into(),
- b.into(),
- self.alias_relate_direction(),
- ))]);
- }
-
- /// Relation direction emitted for `AliasRelate` predicates, corresponding to the direction
- /// of the relation.
- fn alias_relate_direction(&self) -> ty::AliasRelationDirection;
+ /// Register `AliasRelate` obligation(s) that both types must be related to each other.
+ fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>);
}
fn int_unification_error<'tcx>(
diff --git a/compiler/rustc_infer/src/infer/relate/equate.rs b/compiler/rustc_infer/src/infer/relate/equate.rs
deleted file mode 100644
index 1617a062ea0..00000000000
--- a/compiler/rustc_infer/src/infer/relate/equate.rs
+++ /dev/null
@@ -1,228 +0,0 @@
-use super::combine::{CombineFields, ObligationEmittingRelation};
-use super::StructurallyRelateAliases;
-use crate::infer::BoundRegionConversionTime::HigherRankedType;
-use crate::infer::{DefineOpaqueTypes, SubregionOrigin};
-use crate::traits::PredicateObligations;
-
-use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
-use rustc_middle::ty::GenericArgsRef;
-use rustc_middle::ty::TyVar;
-use rustc_middle::ty::{self, Ty, TyCtxt};
-
-use rustc_hir::def_id::DefId;
-use rustc_span::Span;
-
-/// Ensures `a` is made equal to `b`. Returns `a` on success.
-pub struct Equate<'combine, 'infcx, 'tcx> {
- fields: &'combine mut CombineFields<'infcx, 'tcx>,
- structurally_relate_aliases: StructurallyRelateAliases,
- a_is_expected: bool,
-}
-
-impl<'combine, 'infcx, 'tcx> Equate<'combine, 'infcx, 'tcx> {
- pub fn new(
- fields: &'combine mut CombineFields<'infcx, 'tcx>,
- structurally_relate_aliases: StructurallyRelateAliases,
- a_is_expected: bool,
- ) -> Equate<'combine, 'infcx, 'tcx> {
- Equate { fields, structurally_relate_aliases, a_is_expected }
- }
-}
-
-impl<'tcx> TypeRelation<'tcx> for Equate<'_, '_, 'tcx> {
- fn tag(&self) -> &'static str {
- "Equate"
- }
-
- fn tcx(&self) -> TyCtxt<'tcx> {
- self.fields.tcx()
- }
-
- fn a_is_expected(&self) -> bool {
- self.a_is_expected
- }
-
- fn relate_item_args(
- &mut self,
- _item_def_id: DefId,
- a_arg: GenericArgsRef<'tcx>,
- b_arg: GenericArgsRef<'tcx>,
- ) -> RelateResult<'tcx, GenericArgsRef<'tcx>> {
- // N.B., once we are equating types, we don't care about
- // variance, so don't try to lookup the variance here. This
- // also avoids some cycles (e.g., #41849) since looking up
- // variance requires computing types which can require
- // performing trait matching (which then performs equality
- // unification).
-
- relate::relate_args_invariantly(self, a_arg, b_arg)
- }
-
- fn relate_with_variance<T: Relate<'tcx>>(
- &mut self,
- _: ty::Variance,
- _info: ty::VarianceDiagInfo<'tcx>,
- a: T,
- b: T,
- ) -> RelateResult<'tcx, T> {
- self.relate(a, b)
- }
-
- #[instrument(skip(self), level = "debug")]
- fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
- if a == b {
- return Ok(a);
- }
-
- trace!(a = ?a.kind(), b = ?b.kind());
-
- let infcx = self.fields.infcx;
-
- let a = infcx.inner.borrow_mut().type_variables().replace_if_possible(a);
- let b = infcx.inner.borrow_mut().type_variables().replace_if_possible(b);
-
- match (a.kind(), b.kind()) {
- (&ty::Infer(TyVar(a_id)), &ty::Infer(TyVar(b_id))) => {
- infcx.inner.borrow_mut().type_variables().equate(a_id, b_id);
- }
-
- (&ty::Infer(TyVar(a_vid)), _) => {
- infcx.instantiate_ty_var(self, self.a_is_expected, a_vid, ty::Invariant, b)?;
- }
-
- (_, &ty::Infer(TyVar(b_vid))) => {
- infcx.instantiate_ty_var(self, !self.a_is_expected, b_vid, ty::Invariant, a)?;
- }
-
- (&ty::Error(e), _) | (_, &ty::Error(e)) => {
- infcx.set_tainted_by_errors(e);
- return Ok(Ty::new_error(self.tcx(), e));
- }
-
- (
- &ty::Alias(ty::Opaque, ty::AliasTy { def_id: a_def_id, .. }),
- &ty::Alias(ty::Opaque, ty::AliasTy { def_id: b_def_id, .. }),
- ) if a_def_id == b_def_id => {
- infcx.super_combine_tys(self, a, b)?;
- }
- (&ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }), _)
- | (_, &ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }))
- if self.fields.define_opaque_types == DefineOpaqueTypes::Yes
- && def_id.is_local()
- && !self.fields.infcx.next_trait_solver() =>
- {
- self.fields.obligations.extend(
- infcx
- .handle_opaque_type(
- a,
- b,
- self.a_is_expected(),
- &self.fields.trace.cause,
- self.param_env(),
- )?
- .obligations,
- );
- }
- _ => {
- infcx.super_combine_tys(self, a, b)?;
- }
- }
-
- Ok(a)
- }
-
- fn regions(
- &mut self,
- a: ty::Region<'tcx>,
- b: ty::Region<'tcx>,
- ) -> RelateResult<'tcx, ty::Region<'tcx>> {
- debug!("{}.regions({:?}, {:?})", self.tag(), a, b);
- let origin = SubregionOrigin::Subtype(Box::new(self.fields.trace.clone()));
- self.fields
- .infcx
- .inner
- .borrow_mut()
- .unwrap_region_constraints()
- .make_eqregion(origin, a, b);
- Ok(a)
- }
-
- fn consts(
- &mut self,
- a: ty::Const<'tcx>,
- b: ty::Const<'tcx>,
- ) -> RelateResult<'tcx, ty::Const<'tcx>> {
- self.fields.infcx.super_combine_consts(self, a, b)
- }
-
- fn binders<T>(
- &mut self,
- a: ty::Binder<'tcx, T>,
- b: ty::Binder<'tcx, T>,
- ) -> RelateResult<'tcx, ty::Binder<'tcx, T>>
- where
- T: Relate<'tcx>,
- {
- // A binder is equal to itself if it's structurally equal to itself
- if a == b {
- return Ok(a);
- }
-
- if let (Some(a), Some(b)) = (a.no_bound_vars(), b.no_bound_vars()) {
- // Fast path for the common case.
- self.relate(a, b)?;
- } else {
- // When equating binders, we check that there is a 1-to-1
- // correspondence between the bound vars in both types.
- //
- // We do so by separately instantiating one of the binders with
- // placeholders and the other with inference variables and then
- // equating the instantiated types.
- //
- // We want `for<..> A == for<..> B` -- therefore we want
- // `exists<..> A == for<..> B` and `exists<..> B == for<..> A`.
-
- let span = self.fields.trace.cause.span;
- let infcx = self.fields.infcx;
-
- // Check if `exists<..> A == for<..> B`
- infcx.enter_forall(b, |b| {
- let a = infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, a);
- self.relate(a, b)
- })?;
-
- // Check if `exists<..> B == for<..> A`.
- infcx.enter_forall(a, |a| {
- let b = infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, b);
- self.relate(a, b)
- })?;
- }
- Ok(a)
- }
-}
-
-impl<'tcx> ObligationEmittingRelation<'tcx> for Equate<'_, '_, 'tcx> {
- fn span(&self) -> Span {
- self.fields.trace.span()
- }
-
- fn structurally_relate_aliases(&self) -> StructurallyRelateAliases {
- self.structurally_relate_aliases
- }
-
- fn param_env(&self) -> ty::ParamEnv<'tcx> {
- self.fields.param_env
- }
-
- fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>) {
- self.fields.register_predicates(obligations);
- }
-
- fn register_obligations(&mut self, obligations: PredicateObligations<'tcx>) {
- self.fields.register_obligations(obligations);
- }
-
- fn alias_relate_direction(&self) -> ty::AliasRelationDirection {
- ty::AliasRelationDirection::Equate
- }
-}
diff --git a/compiler/rustc_infer/src/infer/relate/glb.rs b/compiler/rustc_infer/src/infer/relate/glb.rs
index 52a2f4c7347..9b77e6888b2 100644
--- a/compiler/rustc_infer/src/infer/relate/glb.rs
+++ b/compiler/rustc_infer/src/infer/relate/glb.rs
@@ -158,8 +158,12 @@ impl<'tcx> ObligationEmittingRelation<'tcx> for Glb<'_, '_, 'tcx> {
self.fields.register_obligations(obligations);
}
- fn alias_relate_direction(&self) -> ty::AliasRelationDirection {
- // FIXME(deferred_projection_equality): This isn't right, I think?
- ty::AliasRelationDirection::Equate
+ fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
+ self.register_predicates([ty::Binder::dummy(ty::PredicateKind::AliasRelate(
+ a.into(),
+ b.into(),
+ // FIXME(deferred_projection_equality): This isn't right, I think?
+ ty::AliasRelationDirection::Equate,
+ ))]);
}
}
diff --git a/compiler/rustc_infer/src/infer/relate/lub.rs b/compiler/rustc_infer/src/infer/relate/lub.rs
index fa0da64ca65..db04e3231d6 100644
--- a/compiler/rustc_infer/src/infer/relate/lub.rs
+++ b/compiler/rustc_infer/src/infer/relate/lub.rs
@@ -158,8 +158,12 @@ impl<'tcx> ObligationEmittingRelation<'tcx> for Lub<'_, '_, 'tcx> {
self.fields.register_obligations(obligations)
}
- fn alias_relate_direction(&self) -> ty::AliasRelationDirection {
- // FIXME(deferred_projection_equality): This isn't right, I think?
- ty::AliasRelationDirection::Equate
+ fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
+ self.register_predicates([ty::Binder::dummy(ty::PredicateKind::AliasRelate(
+ a.into(),
+ b.into(),
+ // FIXME(deferred_projection_equality): This isn't right, I think?
+ ty::AliasRelationDirection::Equate,
+ ))]);
}
}
diff --git a/compiler/rustc_infer/src/infer/relate/mod.rs b/compiler/rustc_infer/src/infer/relate/mod.rs
index 8619cc502ad..86a01130167 100644
--- a/compiler/rustc_infer/src/infer/relate/mod.rs
+++ b/compiler/rustc_infer/src/infer/relate/mod.rs
@@ -2,13 +2,12 @@
//! (except for some relations used for diagnostics and heuristics in the compiler).
pub(super) mod combine;
-mod equate;
mod generalize;
mod glb;
mod higher_ranked;
mod lattice;
mod lub;
-mod sub;
+mod type_relating;
/// Whether aliases should be related structurally or not. Used
/// to adjust the behavior of generalization and combine.
diff --git a/compiler/rustc_infer/src/infer/relate/sub.rs b/compiler/rustc_infer/src/infer/relate/sub.rs
deleted file mode 100644
index 2cc8d0d3b10..00000000000
--- a/compiler/rustc_infer/src/infer/relate/sub.rs
+++ /dev/null
@@ -1,229 +0,0 @@
-use super::combine::CombineFields;
-use super::StructurallyRelateAliases;
-use crate::infer::{DefineOpaqueTypes, ObligationEmittingRelation, SubregionOrigin};
-use crate::traits::{Obligation, PredicateObligations};
-
-use rustc_middle::ty::relate::{Cause, Relate, RelateResult, TypeRelation};
-use rustc_middle::ty::visit::TypeVisitableExt;
-use rustc_middle::ty::TyVar;
-use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_span::Span;
-use std::mem;
-
-/// Ensures `a` is made a subtype of `b`. Returns `a` on success.
-pub struct Sub<'combine, 'a, 'tcx> {
- fields: &'combine mut CombineFields<'a, 'tcx>,
- a_is_expected: bool,
-}
-
-impl<'combine, 'infcx, 'tcx> Sub<'combine, 'infcx, 'tcx> {
- pub fn new(
- f: &'combine mut CombineFields<'infcx, 'tcx>,
- a_is_expected: bool,
- ) -> Sub<'combine, 'infcx, 'tcx> {
- Sub { fields: f, a_is_expected }
- }
-
- fn with_expected_switched<R, F: FnOnce(&mut Self) -> R>(&mut self, f: F) -> R {
- self.a_is_expected = !self.a_is_expected;
- let result = f(self);
- self.a_is_expected = !self.a_is_expected;
- result
- }
-}
-
-impl<'tcx> TypeRelation<'tcx> for Sub<'_, '_, 'tcx> {
- fn tag(&self) -> &'static str {
- "Sub"
- }
-
- fn tcx(&self) -> TyCtxt<'tcx> {
- self.fields.infcx.tcx
- }
-
- fn a_is_expected(&self) -> bool {
- self.a_is_expected
- }
-
- fn with_cause<F, R>(&mut self, cause: Cause, f: F) -> R
- where
- F: FnOnce(&mut Self) -> R,
- {
- debug!("sub with_cause={:?}", cause);
- let old_cause = mem::replace(&mut self.fields.cause, Some(cause));
- let r = f(self);
- debug!("sub old_cause={:?}", old_cause);
- self.fields.cause = old_cause;
- r
- }
-
- fn relate_with_variance<T: Relate<'tcx>>(
- &mut self,
- variance: ty::Variance,
- _info: ty::VarianceDiagInfo<'tcx>,
- a: T,
- b: T,
- ) -> RelateResult<'tcx, T> {
- match variance {
- ty::Invariant => {
- self.fields.equate(StructurallyRelateAliases::No, self.a_is_expected).relate(a, b)
- }
- ty::Covariant => self.relate(a, b),
- ty::Bivariant => Ok(a),
- ty::Contravariant => self.with_expected_switched(|this| this.relate(b, a)),
- }
- }
-
- #[instrument(skip(self), level = "debug")]
- fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
- if a == b {
- return Ok(a);
- }
-
- let infcx = self.fields.infcx;
- let a = infcx.inner.borrow_mut().type_variables().replace_if_possible(a);
- let b = infcx.inner.borrow_mut().type_variables().replace_if_possible(b);
-
- match (a.kind(), b.kind()) {
- (&ty::Infer(TyVar(_)), &ty::Infer(TyVar(_))) => {
- // Shouldn't have any LBR here, so we can safely put
- // this under a binder below without fear of accidental
- // capture.
- assert!(!a.has_escaping_bound_vars());
- assert!(!b.has_escaping_bound_vars());
-
- // can't make progress on `A <: B` if both A and B are
- // type variables, so record an obligation.
- self.fields.obligations.push(Obligation::new(
- self.tcx(),
- self.fields.trace.cause.clone(),
- self.fields.param_env,
- ty::Binder::dummy(ty::PredicateKind::Subtype(ty::SubtypePredicate {
- a_is_expected: self.a_is_expected,
- a,
- b,
- })),
- ));
-
- Ok(a)
- }
- (&ty::Infer(TyVar(a_vid)), _) => {
- infcx.instantiate_ty_var(self, self.a_is_expected, a_vid, ty::Covariant, b)?;
- Ok(a)
- }
- (_, &ty::Infer(TyVar(b_vid))) => {
- infcx.instantiate_ty_var(self, !self.a_is_expected, b_vid, ty::Contravariant, a)?;
- Ok(a)
- }
-
- (&ty::Error(e), _) | (_, &ty::Error(e)) => {
- infcx.set_tainted_by_errors(e);
- Ok(Ty::new_error(self.tcx(), e))
- }
-
- (
- &ty::Alias(ty::Opaque, ty::AliasTy { def_id: a_def_id, .. }),
- &ty::Alias(ty::Opaque, ty::AliasTy { def_id: b_def_id, .. }),
- ) if a_def_id == b_def_id => {
- self.fields.infcx.super_combine_tys(self, a, b)?;
- Ok(a)
- }
- (&ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }), _)
- | (_, &ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }))
- if self.fields.define_opaque_types == DefineOpaqueTypes::Yes
- && def_id.is_local()
- && !self.fields.infcx.next_trait_solver() =>
- {
- self.fields.obligations.extend(
- infcx
- .handle_opaque_type(
- a,
- b,
- self.a_is_expected,
- &self.fields.trace.cause,
- self.param_env(),
- )?
- .obligations,
- );
- Ok(a)
- }
- _ => {
- self.fields.infcx.super_combine_tys(self, a, b)?;
- Ok(a)
- }
- }
- }
-
- fn regions(
- &mut self,
- a: ty::Region<'tcx>,
- b: ty::Region<'tcx>,
- ) -> RelateResult<'tcx, ty::Region<'tcx>> {
- debug!("{}.regions({:?}, {:?}) self.cause={:?}", self.tag(), a, b, self.fields.cause);
-
- // FIXME -- we have more fine-grained information available
- // 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, b, a);
-
- Ok(a)
- }
-
- fn consts(
- &mut self,
- a: ty::Const<'tcx>,
- b: ty::Const<'tcx>,
- ) -> RelateResult<'tcx, ty::Const<'tcx>> {
- self.fields.infcx.super_combine_consts(self, a, b)
- }
-
- fn binders<T>(
- &mut self,
- a: ty::Binder<'tcx, T>,
- b: ty::Binder<'tcx, T>,
- ) -> RelateResult<'tcx, ty::Binder<'tcx, T>>
- where
- T: Relate<'tcx>,
- {
- // A binder is always a subtype of itself if it's structurally equal to itself
- if a == b {
- return Ok(a);
- }
-
- self.fields.higher_ranked_sub(a, b, self.a_is_expected)?;
- Ok(a)
- }
-}
-
-impl<'tcx> ObligationEmittingRelation<'tcx> for Sub<'_, '_, 'tcx> {
- fn span(&self) -> Span {
- self.fields.trace.span()
- }
-
- fn structurally_relate_aliases(&self) -> StructurallyRelateAliases {
- StructurallyRelateAliases::No
- }
-
- fn param_env(&self) -> ty::ParamEnv<'tcx> {
- self.fields.param_env
- }
-
- fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>) {
- self.fields.register_predicates(obligations);
- }
-
- fn register_obligations(&mut self, obligations: PredicateObligations<'tcx>) {
- self.fields.register_obligations(obligations);
- }
-
- fn alias_relate_direction(&self) -> ty::AliasRelationDirection {
- ty::AliasRelationDirection::Subtype
- }
-}
diff --git a/compiler/rustc_infer/src/infer/relate/type_relating.rs b/compiler/rustc_infer/src/infer/relate/type_relating.rs
new file mode 100644
index 00000000000..c4de324e6ff
--- /dev/null
+++ b/compiler/rustc_infer/src/infer/relate/type_relating.rs
@@ -0,0 +1,325 @@
+use super::combine::CombineFields;
+use crate::infer::{
+ DefineOpaqueTypes, ObligationEmittingRelation, StructurallyRelateAliases, SubregionOrigin,
+};
+use crate::traits::{Obligation, PredicateObligations};
+
+use rustc_middle::ty::relate::{Cause, Relate, RelateResult, TypeRelation};
+use rustc_middle::ty::visit::TypeVisitableExt;
+use rustc_middle::ty::TyVar;
+use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_span::Span;
+use std::mem;
+
+/// Enforce that `a` is equal to or a subtype of `b`.
+pub struct TypeRelating<'combine, 'a, 'tcx> {
+ fields: &'combine mut CombineFields<'a, 'tcx>,
+ a_is_expected: bool,
+ structurally_relate_aliases: StructurallyRelateAliases,
+ ambient_variance: ty::Variance,
+}
+
+impl<'combine, 'infcx, 'tcx> TypeRelating<'combine, 'infcx, 'tcx> {
+ pub fn new(
+ f: &'combine mut CombineFields<'infcx, 'tcx>,
+ a_is_expected: bool,
+ structurally_relate_aliases: StructurallyRelateAliases,
+ ambient_variance: ty::Variance,
+ ) -> TypeRelating<'combine, 'infcx, 'tcx> {
+ TypeRelating { fields: f, a_is_expected, structurally_relate_aliases, ambient_variance }
+ }
+}
+
+impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
+ fn tag(&self) -> &'static str {
+ "TypeRelating"
+ }
+
+ fn tcx(&self) -> TyCtxt<'tcx> {
+ self.fields.infcx.tcx
+ }
+
+ fn a_is_expected(&self) -> bool {
+ self.a_is_expected
+ }
+
+ fn with_cause<F, R>(&mut self, cause: Cause, f: F) -> R
+ where
+ F: FnOnce(&mut Self) -> R,
+ {
+ debug!("sub with_cause={:?}", cause);
+ let old_cause = mem::replace(&mut self.fields.cause, Some(cause));
+ let r = f(self);
+ debug!("sub old_cause={:?}", old_cause);
+ self.fields.cause = old_cause;
+ r
+ }
+
+ fn relate_with_variance<T: Relate<'tcx>>(
+ &mut self,
+ variance: ty::Variance,
+ _info: ty::VarianceDiagInfo<'tcx>,
+ a: T,
+ b: T,
+ ) -> RelateResult<'tcx, T> {
+ let old_ambient_variance = self.ambient_variance;
+ self.ambient_variance = self.ambient_variance.xform(variance);
+ debug!(?self.ambient_variance, "new ambient variance");
+
+ let r = if self.ambient_variance == ty::Bivariant { Ok(a) } else { self.relate(a, b) };
+
+ self.ambient_variance = old_ambient_variance;
+ r
+ }
+
+ #[instrument(skip(self), level = "debug")]
+ fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
+ if a == b {
+ return Ok(a);
+ }
+
+ let infcx = self.fields.infcx;
+ let a = infcx.inner.borrow_mut().type_variables().replace_if_possible(a);
+ let b = infcx.inner.borrow_mut().type_variables().replace_if_possible(b);
+
+ match (a.kind(), b.kind()) {
+ (&ty::Infer(TyVar(a_id)), &ty::Infer(TyVar(b_id))) => {
+ // Shouldn't have any LBR here, so we can safely put
+ // this under a binder below without fear of accidental
+ // capture.
+ assert!(!a.has_escaping_bound_vars());
+ assert!(!b.has_escaping_bound_vars());
+
+ match self.ambient_variance {
+ ty::Covariant => {
+ // can't make progress on `A <: B` if both A and B are
+ // type variables, so record an obligation.
+ self.fields.obligations.push(Obligation::new(
+ self.tcx(),
+ self.fields.trace.cause.clone(),
+ self.fields.param_env,
+ ty::Binder::dummy(ty::PredicateKind::Subtype(ty::SubtypePredicate {
+ a_is_expected: self.a_is_expected,
+ a,
+ b,
+ })),
+ ));
+ }
+ ty::Contravariant => {
+ // can't make progress on `B <: A` if both A and B are
+ // type variables, so record an obligation.
+ self.fields.obligations.push(Obligation::new(
+ self.tcx(),
+ self.fields.trace.cause.clone(),
+ self.fields.param_env,
+ ty::Binder::dummy(ty::PredicateKind::Subtype(ty::SubtypePredicate {
+ a_is_expected: !self.a_is_expected,
+ a: b,
+ b: a,
+ })),
+ ));
+ }
+ ty::Invariant => {
+ infcx.inner.borrow_mut().type_variables().equate(a_id, b_id);
+ }
+ ty::Bivariant => {
+ unreachable!("Expected bivariance to be handled in relate_with_variance")
+ }
+ }
+ }
+
+ (&ty::Infer(TyVar(a_vid)), _) => {
+ infcx.instantiate_ty_var(
+ self,
+ self.a_is_expected,
+ a_vid,
+ self.ambient_variance,
+ b,
+ )?;
+ }
+ (_, &ty::Infer(TyVar(b_vid))) => {
+ infcx.instantiate_ty_var(
+ self,
+ !self.a_is_expected,
+ b_vid,
+ self.ambient_variance.xform(ty::Contravariant),
+ a,
+ )?;
+ }
+
+ (&ty::Error(e), _) | (_, &ty::Error(e)) => {
+ infcx.set_tainted_by_errors(e);
+ return Ok(Ty::new_error(self.tcx(), e));
+ }
+
+ (
+ &ty::Alias(ty::Opaque, ty::AliasTy { def_id: a_def_id, .. }),
+ &ty::Alias(ty::Opaque, ty::AliasTy { def_id: b_def_id, .. }),
+ ) if a_def_id == b_def_id => {
+ infcx.super_combine_tys(self, a, b)?;
+ }
+
+ (&ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }), _)
+ | (_, &ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }))
+ if self.fields.define_opaque_types == DefineOpaqueTypes::Yes
+ && def_id.is_local()
+ && !infcx.next_trait_solver() =>
+ {
+ self.fields.obligations.extend(
+ infcx
+ .handle_opaque_type(
+ a,
+ b,
+ self.a_is_expected,
+ &self.fields.trace.cause,
+ self.param_env(),
+ )?
+ .obligations,
+ );
+ }
+
+ _ => {
+ infcx.super_combine_tys(self, a, b)?;
+ }
+ }
+
+ Ok(a)
+ }
+
+ fn regions(
+ &mut self,
+ a: ty::Region<'tcx>,
+ b: ty::Region<'tcx>,
+ ) -> RelateResult<'tcx, ty::Region<'tcx>> {
+ debug!("{}.regions({:?}, {:?}) self.cause={:?}", self.tag(), a, b, self.fields.cause);
+
+ // FIXME -- we have more fine-grained information available
+ // from the "cause" field, we could perhaps give more tailored
+ // error messages.
+ let origin = SubregionOrigin::Subtype(Box::new(self.fields.trace.clone()));
+
+ match self.ambient_variance {
+ // Subtype(&'a u8, &'b u8) => Outlives('a: 'b) => SubRegion('b, 'a)
+ ty::Covariant => {
+ self.fields
+ .infcx
+ .inner
+ .borrow_mut()
+ .unwrap_region_constraints()
+ .make_subregion(origin, b, a);
+ }
+ // Suptype(&'a u8, &'b u8) => Outlives('b: 'a) => SubRegion('a, 'b)
+ ty::Contravariant => {
+ self.fields
+ .infcx
+ .inner
+ .borrow_mut()
+ .unwrap_region_constraints()
+ .make_subregion(origin, a, b);
+ }
+ ty::Invariant => {
+ // The order of `make_eqregion` apparently matters.
+ self.fields
+ .infcx
+ .inner
+ .borrow_mut()
+ .unwrap_region_constraints()
+ .make_eqregion(origin, a, b);
+ }
+ ty::Bivariant => {
+ unreachable!("Expected bivariance to be handled in relate_with_variance")
+ }
+ }
+
+ Ok(a)
+ }
+
+ fn consts(
+ &mut self,
+ a: ty::Const<'tcx>,
+ b: ty::Const<'tcx>,
+ ) -> RelateResult<'tcx, ty::Const<'tcx>> {
+ self.fields.infcx.super_combine_consts(self, a, b)
+ }
+
+ fn binders<T>(
+ &mut self,
+ a: ty::Binder<'tcx, T>,
+ b: ty::Binder<'tcx, T>,
+ ) -> RelateResult<'tcx, ty::Binder<'tcx, T>>
+ where
+ T: Relate<'tcx>,
+ {
+ if a == b {
+ // Do nothing
+ } else if let Some(a) = a.no_bound_vars()
+ && let Some(b) = b.no_bound_vars()
+ {
+ self.relate(a, b)?;
+ } else {
+ match self.ambient_variance {
+ ty::Covariant => {
+ self.fields.higher_ranked_sub(a, b, self.a_is_expected)?;
+ }
+ ty::Contravariant => {
+ self.fields.higher_ranked_sub(b, a, !self.a_is_expected)?;
+ }
+ ty::Invariant => {
+ self.fields.higher_ranked_sub(a, b, self.a_is_expected)?;
+ self.fields.higher_ranked_sub(b, a, !self.a_is_expected)?;
+ }
+ ty::Bivariant => {
+ unreachable!("Expected bivariance to be handled in relate_with_variance")
+ }
+ }
+ }
+
+ Ok(a)
+ }
+}
+
+impl<'tcx> ObligationEmittingRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
+ fn span(&self) -> Span {
+ self.fields.trace.span()
+ }
+
+ fn param_env(&self) -> ty::ParamEnv<'tcx> {
+ self.fields.param_env
+ }
+
+ fn structurally_relate_aliases(&self) -> StructurallyRelateAliases {
+ self.structurally_relate_aliases
+ }
+
+ fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>) {
+ self.fields.register_predicates(obligations);
+ }
+
+ fn register_obligations(&mut self, obligations: PredicateObligations<'tcx>) {
+ self.fields.register_obligations(obligations);
+ }
+
+ fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
+ self.register_predicates([ty::Binder::dummy(match self.ambient_variance {
+ ty::Variance::Covariant => ty::PredicateKind::AliasRelate(
+ a.into(),
+ b.into(),
+ ty::AliasRelationDirection::Subtype,
+ ),
+ // a :> b is b <: a
+ ty::Variance::Contravariant => ty::PredicateKind::AliasRelate(
+ b.into(),
+ a.into(),
+ ty::AliasRelationDirection::Subtype,
+ ),
+ ty::Variance::Invariant => ty::PredicateKind::AliasRelate(
+ a.into(),
+ b.into(),
+ ty::AliasRelationDirection::Equate,
+ ),
+ ty::Variance::Bivariant => {
+ unreachable!("Expected bivariance to be handled in relate_with_variance")
+ }
+ })]);
+ }
+}
From 801dd1d061bc6db31547d45c64a32bbd9b4f6124 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 26 Feb 2024 15:58:53 +0000
Subject: [PATCH 3/7] Remove cause
---
compiler/rustc_infer/src/infer/mod.rs | 1 -
.../rustc_infer/src/infer/relate/combine.rs | 1 -
.../src/infer/relate/type_relating.rs | 24 ++-----------------
compiler/rustc_middle/src/ty/relate.rs | 17 +++++--------
4 files changed, 8 insertions(+), 35 deletions(-)
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 6f52ded3551..b99ea35c22c 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -836,7 +836,6 @@ impl<'tcx> InferCtxt<'tcx> {
CombineFields {
infcx: self,
trace,
- cause: None,
param_env,
obligations: PredicateObligations::new(),
define_opaque_types,
diff --git a/compiler/rustc_infer/src/infer/relate/combine.rs b/compiler/rustc_infer/src/infer/relate/combine.rs
index 0a550660f94..749c50b57b5 100644
--- a/compiler/rustc_infer/src/infer/relate/combine.rs
+++ b/compiler/rustc_infer/src/infer/relate/combine.rs
@@ -42,7 +42,6 @@ use rustc_span::Span;
pub struct CombineFields<'infcx, 'tcx> {
pub infcx: &'infcx InferCtxt<'tcx>,
pub trace: TypeTrace<'tcx>,
- pub cause: Option<ty::relate::Cause>,
pub param_env: ty::ParamEnv<'tcx>,
pub obligations: PredicateObligations<'tcx>,
pub define_opaque_types: DefineOpaqueTypes,
diff --git a/compiler/rustc_infer/src/infer/relate/type_relating.rs b/compiler/rustc_infer/src/infer/relate/type_relating.rs
index c4de324e6ff..ddc4bf9a514 100644
--- a/compiler/rustc_infer/src/infer/relate/type_relating.rs
+++ b/compiler/rustc_infer/src/infer/relate/type_relating.rs
@@ -4,12 +4,10 @@ use crate::infer::{
};
use crate::traits::{Obligation, PredicateObligations};
-use rustc_middle::ty::relate::{Cause, Relate, RelateResult, TypeRelation};
-use rustc_middle::ty::visit::TypeVisitableExt;
+use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation};
use rustc_middle::ty::TyVar;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_span::Span;
-use std::mem;
/// Enforce that `a` is equal to or a subtype of `b`.
pub struct TypeRelating<'combine, 'a, 'tcx> {
@@ -43,18 +41,6 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
self.a_is_expected
}
- fn with_cause<F, R>(&mut self, cause: Cause, f: F) -> R
- where
- F: FnOnce(&mut Self) -> R,
- {
- debug!("sub with_cause={:?}", cause);
- let old_cause = mem::replace(&mut self.fields.cause, Some(cause));
- let r = f(self);
- debug!("sub old_cause={:?}", old_cause);
- self.fields.cause = old_cause;
- r
- }
-
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
@@ -84,12 +70,6 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
match (a.kind(), b.kind()) {
(&ty::Infer(TyVar(a_id)), &ty::Infer(TyVar(b_id))) => {
- // Shouldn't have any LBR here, so we can safely put
- // this under a binder below without fear of accidental
- // capture.
- assert!(!a.has_escaping_bound_vars());
- assert!(!b.has_escaping_bound_vars());
-
match self.ambient_variance {
ty::Covariant => {
// can't make progress on `A <: B` if both A and B are
@@ -191,7 +171,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
a: ty::Region<'tcx>,
b: ty::Region<'tcx>,
) -> RelateResult<'tcx, ty::Region<'tcx>> {
- debug!("{}.regions({:?}, {:?}) self.cause={:?}", self.tag(), a, b, self.fields.cause);
+ debug!("{}.regions({:?}, {:?})", self.tag(), a, b);
// FIXME -- we have more fine-grained information available
// from the "cause" field, we could perhaps give more tailored
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index 303f285b00c..abd39914cfd 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -30,13 +30,6 @@ pub trait TypeRelation<'tcx>: Sized {
/// relation. Just affects error messages.
fn a_is_expected(&self) -> bool;
- fn with_cause<F, R>(&mut self, _cause: Cause, f: F) -> R
- where
- F: FnOnce(&mut Self) -> R,
- {
- f(self)
- }
-
/// Generic relation routine suitable for most anything.
fn relate<T: Relate<'tcx>>(&mut self, a: T, b: T) -> RelateResult<'tcx, T> {
Relate::relate(self, a, b)
@@ -452,10 +445,12 @@ pub fn structurally_relate_tys<'tcx, R: TypeRelation<'tcx>>(
(&ty::Dynamic(a_obj, a_region, a_repr), &ty::Dynamic(b_obj, b_region, b_repr))
if a_repr == b_repr =>
{
- let region_bound = relation.with_cause(Cause::ExistentialRegionBound, |relation| {
- relation.relate(a_region, b_region)
- })?;
- Ok(Ty::new_dynamic(tcx, relation.relate(a_obj, b_obj)?, region_bound, a_repr))
+ Ok(Ty::new_dynamic(
+ tcx,
+ relation.relate(a_obj, b_obj)?,
+ relation.relate(a_region, b_region)?,
+ a_repr,
+ ))
}
(&ty::Coroutine(a_id, a_args), &ty::Coroutine(b_id, b_args)) if a_id == b_id => {
From 61daee66a89f52eb5fa6f103d5ac8dbcaa885709 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 26 Feb 2024 19:52:52 +0000
Subject: [PATCH 4/7] Get rid of some sub_exp and eq_exp
---
compiler/rustc_borrowck/src/type_check/mod.rs | 1 -
compiler/rustc_hir_typeck/src/coercion.rs | 38 +++++++++----------
compiler/rustc_infer/src/infer/mod.rs | 6 ++-
.../rustc_infer/src/infer/opaque_types.rs | 12 ++----
.../src/solve/eval_ctxt/mod.rs | 1 -
.../src/traits/engine.rs | 18 ---------
.../error_reporting/type_err_ctxt_ext.rs | 13 +++++--
.../opaque-type-unsatisfied-bound.rs | 6 +--
.../opaque-type-unsatisfied-bound.stderr | 6 +--
.../opaque-type-unsatisfied-fn-bound.rs | 2 +-
.../opaque-type-unsatisfied-fn-bound.stderr | 2 +-
.../itiat-allow-nested-closures.bad.stderr | 3 ++
12 files changed, 48 insertions(+), 60 deletions(-)
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 75cc28bcab0..26e1e24d1a1 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -1066,7 +1066,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
&cause,
param_env,
hidden_ty.ty,
- true,
&mut obligations,
)?;
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index 179255993b4..792359c9dda 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -1493,6 +1493,21 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
return;
}
+ let (expected, found) = if label_expression_as_expected {
+ // In the case where this is a "forced unit", like
+ // `break`, we want to call the `()` "expected"
+ // since it is implied by the syntax.
+ // (Note: not all force-units work this way.)"
+ (expression_ty, self.merged_ty())
+ } else {
+ // Otherwise, the "expected" type for error
+ // reporting is the current unification type,
+ // which is basically the LUB of the expressions
+ // we've seen so far (combined with the expected
+ // type)
+ (self.merged_ty(), expression_ty)
+ };
+
// Handle the actual type unification etc.
let result = if let Some(expression) = expression {
if self.pushed == 0 {
@@ -1540,12 +1555,11 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
// Another example is `break` with no argument expression.
assert!(expression_ty.is_unit(), "if let hack without unit type");
fcx.at(cause, fcx.param_env)
- // needed for tests/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs
- .eq_exp(
+ .eq(
+ // needed for tests/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs
DefineOpaqueTypes::Yes,
- label_expression_as_expected,
- expression_ty,
- self.merged_ty(),
+ expected,
+ found,
)
.map(|infer_ok| {
fcx.register_infer_ok_obligations(infer_ok);
@@ -1579,20 +1593,6 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
fcx.set_tainted_by_errors(
fcx.dcx().span_delayed_bug(cause.span, "coercion error but no error emitted"),
);
- let (expected, found) = if label_expression_as_expected {
- // In the case where this is a "forced unit", like
- // `break`, we want to call the `()` "expected"
- // since it is implied by the syntax.
- // (Note: not all force-units work this way.)"
- (expression_ty, self.merged_ty())
- } else {
- // Otherwise, the "expected" type for error
- // reporting is the current unification type,
- // which is basically the LUB of the expressions
- // we've seen so far (combined with the expected
- // type)
- (self.merged_ty(), expression_ty)
- };
let (expected, found) = fcx.resolve_vars_if_possible((expected, found));
let mut err;
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index b99ea35c22c..73a25637e1a 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -1032,7 +1032,11 @@ impl<'tcx> InferCtxt<'tcx> {
}
self.enter_forall(predicate, |ty::SubtypePredicate { a_is_expected, a, b }| {
- Ok(self.at(cause, param_env).sub_exp(DefineOpaqueTypes::No, a_is_expected, a, b))
+ if a_is_expected {
+ Ok(self.at(cause, param_env).sub(DefineOpaqueTypes::No, a, b))
+ } else {
+ Ok(self.at(cause, param_env).sup(DefineOpaqueTypes::No, b, a))
+ }
})
}
diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types.rs
index ec674407e52..d381c77ec66 100644
--- a/compiler/rustc_infer/src/infer/opaque_types.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types.rs
@@ -102,7 +102,7 @@ impl<'tcx> InferCtxt<'tcx> {
return Ok(InferOk { value: (), obligations: vec![] });
}
let (a, b) = if a_is_expected { (a, b) } else { (b, a) };
- let process = |a: Ty<'tcx>, b: Ty<'tcx>, a_is_expected| match *a.kind() {
+ let process = |a: Ty<'tcx>, b: Ty<'tcx>| match *a.kind() {
ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) if def_id.is_local() => {
let def_id = def_id.expect_local();
match self.defining_use_anchor {
@@ -169,14 +169,13 @@ impl<'tcx> InferCtxt<'tcx> {
cause.clone(),
param_env,
b,
- a_is_expected,
))
}
_ => None,
};
- if let Some(res) = process(a, b, true) {
+ if let Some(res) = process(a, b) {
res
- } else if let Some(res) = process(b, a, false) {
+ } else if let Some(res) = process(b, a) {
res
} else {
let (a, b) = self.resolve_vars_if_possible((a, b));
@@ -520,7 +519,6 @@ impl<'tcx> InferCtxt<'tcx> {
cause: ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
hidden_ty: Ty<'tcx>,
- a_is_expected: bool,
) -> InferResult<'tcx, ()> {
let mut obligations = Vec::new();
@@ -529,7 +527,6 @@ impl<'tcx> InferCtxt<'tcx> {
&cause,
param_env,
hidden_ty,
- a_is_expected,
&mut obligations,
)?;
@@ -558,7 +555,6 @@ impl<'tcx> InferCtxt<'tcx> {
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
hidden_ty: Ty<'tcx>,
- a_is_expected: bool,
obligations: &mut Vec<PredicateObligation<'tcx>>,
) -> Result<(), TypeError<'tcx>> {
// Ideally, we'd get the span where *this specific `ty` came
@@ -586,7 +582,7 @@ impl<'tcx> InferCtxt<'tcx> {
if let Some(prev) = prev {
obligations.extend(
self.at(cause, param_env)
- .eq_exp(DefineOpaqueTypes::Yes, a_is_expected, prev, hidden_ty)?
+ .eq(DefineOpaqueTypes::Yes, prev, hidden_ty)?
.obligations,
);
}
diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
index df4dcaff1e7..4a86f708632 100644
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
@@ -904,7 +904,6 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
&ObligationCause::dummy(),
param_env,
hidden_ty,
- true,
&mut obligations,
)?;
self.add_goals(GoalSource::Misc, obligations.into_iter().map(|o| o.into()));
diff --git a/compiler/rustc_trait_selection/src/traits/engine.rs b/compiler/rustc_trait_selection/src/traits/engine.rs
index e789e9c2b6e..9fbec174ce8 100644
--- a/compiler/rustc_trait_selection/src/traits/engine.rs
+++ b/compiler/rustc_trait_selection/src/traits/engine.rs
@@ -116,24 +116,6 @@ impl<'a, 'tcx> ObligationCtxt<'a, 'tcx> {
self.infcx.at(cause, param_env).deeply_normalize(value, &mut **self.engine.borrow_mut())
}
- /// Makes `expected <: actual`.
- pub fn eq_exp<T>(
- &self,
- cause: &ObligationCause<'tcx>,
- param_env: ty::ParamEnv<'tcx>,
- a_is_expected: bool,
- a: T,
- b: T,
- ) -> Result<(), TypeError<'tcx>>
- where
- T: ToTrace<'tcx>,
- {
- self.infcx
- .at(cause, param_env)
- .eq_exp(DefineOpaqueTypes::Yes, a_is_expected, a, b)
- .map(|infer_ok| self.register_infer_ok_obligations(infer_ok))
- }
-
pub fn eq<T: ToTrace<'tcx>>(
&self,
cause: &ObligationCause<'tcx>,
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
index 3275a4f3527..fa8edd11594 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
@@ -1528,6 +1528,12 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
| ObligationCauseCode::Coercion { .. }
);
+ let (expected, actual) = if is_normalized_term_expected {
+ (normalized_term, data.term)
+ } else {
+ (data.term, normalized_term)
+ };
+
// constrain inference variables a bit more to nested obligations from normalize so
// we can have more helpful errors.
//
@@ -1535,12 +1541,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
// since the normalization is just done to improve the error message.
let _ = ocx.select_where_possible();
- if let Err(new_err) = ocx.eq_exp(
+ if let Err(new_err) = ocx.eq(
&obligation.cause,
obligation.param_env,
- is_normalized_term_expected,
- normalized_term,
- data.term,
+ expected,
+ actual,
) {
(Some((data, is_normalized_term_expected, normalized_term, data.term)), new_err)
} else {
diff --git a/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-bound.rs b/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-bound.rs
index 05b167326d4..2607f047024 100644
--- a/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-bound.rs
+++ b/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-bound.rs
@@ -13,8 +13,8 @@ fn main() {
}
fn weird0() -> impl Sized + !Sized {}
-//~^ ERROR type mismatch resolving `() == impl !Sized + Sized`
+//~^ ERROR type mismatch resolving `impl !Sized + Sized == ()`
fn weird1() -> impl !Sized + Sized {}
-//~^ ERROR type mismatch resolving `() == impl !Sized + Sized`
+//~^ ERROR type mismatch resolving `impl !Sized + Sized == ()`
fn weird2() -> impl !Sized {}
-//~^ ERROR type mismatch resolving `() == impl !Sized`
+//~^ ERROR type mismatch resolving `impl !Sized == ()`
diff --git a/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-bound.stderr b/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-bound.stderr
index d803e56e817..ceaf42431fe 100644
--- a/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-bound.stderr
+++ b/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-bound.stderr
@@ -1,16 +1,16 @@
-error[E0271]: type mismatch resolving `() == impl !Sized + Sized`
+error[E0271]: type mismatch resolving `impl !Sized + Sized == ()`
--> $DIR/opaque-type-unsatisfied-bound.rs:15:16
|
LL | fn weird0() -> impl Sized + !Sized {}
| ^^^^^^^^^^^^^^^^^^^ types differ
-error[E0271]: type mismatch resolving `() == impl !Sized + Sized`
+error[E0271]: type mismatch resolving `impl !Sized + Sized == ()`
--> $DIR/opaque-type-unsatisfied-bound.rs:17:16
|
LL | fn weird1() -> impl !Sized + Sized {}
| ^^^^^^^^^^^^^^^^^^^ types differ
-error[E0271]: type mismatch resolving `() == impl !Sized`
+error[E0271]: type mismatch resolving `impl !Sized == ()`
--> $DIR/opaque-type-unsatisfied-bound.rs:19:16
|
LL | fn weird2() -> impl !Sized {}
diff --git a/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-fn-bound.rs b/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-fn-bound.rs
index d714d781c88..9951826a846 100644
--- a/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-fn-bound.rs
+++ b/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-fn-bound.rs
@@ -3,6 +3,6 @@
#![feature(negative_bounds, unboxed_closures)]
fn produce() -> impl !Fn<(u32,)> {}
-//~^ ERROR type mismatch resolving `() == impl !Fn<(u32,)>`
+//~^ ERROR type mismatch resolving `impl !Fn<(u32,)> == ()`
fn main() {}
diff --git a/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-fn-bound.stderr b/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-fn-bound.stderr
index 1fd30410b00..e1b84e0df7a 100644
--- a/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-fn-bound.stderr
+++ b/tests/ui/traits/negative-bounds/opaque-type-unsatisfied-fn-bound.stderr
@@ -1,4 +1,4 @@
-error[E0271]: type mismatch resolving `() == impl !Fn<(u32,)>`
+error[E0271]: type mismatch resolving `impl !Fn<(u32,)> == ()`
--> $DIR/opaque-type-unsatisfied-fn-bound.rs:5:17
|
LL | fn produce() -> impl !Fn<(u32,)> {}
diff --git a/tests/ui/type-alias-impl-trait/itiat-allow-nested-closures.bad.stderr b/tests/ui/type-alias-impl-trait/itiat-allow-nested-closures.bad.stderr
index 4acc47eaef2..9d38e8f36b1 100644
--- a/tests/ui/type-alias-impl-trait/itiat-allow-nested-closures.bad.stderr
+++ b/tests/ui/type-alias-impl-trait/itiat-allow-nested-closures.bad.stderr
@@ -8,6 +8,9 @@ LL | let _: i32 = closure();
| --- ^^^^^^^^^ expected `i32`, found opaque type
| |
| expected due to this
+ |
+ = note: expected type `i32`
+ found opaque type `<() as Foo>::Assoc`
error[E0308]: mismatched types
--> $DIR/itiat-allow-nested-closures.rs:22:9
From 04e22627f5071b548c38bf0963d03f1115416aa9 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 26 Feb 2024 20:42:09 +0000
Subject: [PATCH 5/7] Remove a_is_expected from combine relations
---
.../src/type_check/relate_tys.rs | 1 -
compiler/rustc_infer/src/infer/at.rs | 93 ++++++-------------
.../rustc_infer/src/infer/opaque_types.rs | 8 +-
.../rustc_infer/src/infer/relate/combine.rs | 19 ++--
compiler/rustc_infer/src/infer/relate/glb.rs | 18 ++--
.../src/infer/relate/higher_ranked.rs | 8 +-
compiler/rustc_infer/src/infer/relate/lub.rs | 18 ++--
.../src/infer/relate/type_relating.rs | 36 +++----
.../error_reporting/type_err_ctxt_ext.rs | 9 +-
9 files changed, 75 insertions(+), 135 deletions(-)
diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
index fd6c29379a3..5c5274d7d86 100644
--- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs
+++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
@@ -120,7 +120,6 @@ impl<'me, 'bccx, 'tcx> NllTypeRelating<'me, 'bccx, 'tcx> {
fn relate_opaques(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
let infcx = self.type_checker.infcx;
debug_assert!(!infcx.next_trait_solver());
- let (a, b) = if self.a_is_expected() { (a, b) } else { (b, a) };
// `handle_opaque_type` cannot handle subtyping, so to support subtyping
// we instead eagerly generalize here. This is a bit of a mess but will go
// away once we're using the new solver.
diff --git a/compiler/rustc_infer/src/infer/at.rs b/compiler/rustc_infer/src/infer/at.rs
index a086d89b933..94088216c02 100644
--- a/compiler/rustc_infer/src/infer/at.rs
+++ b/compiler/rustc_infer/src/infer/at.rs
@@ -49,7 +49,6 @@ pub struct At<'a, 'tcx> {
pub struct Trace<'a, 'tcx> {
at: At<'a, 'tcx>,
- a_is_expected: bool,
trace: TypeTrace<'tcx>,
}
@@ -105,23 +104,6 @@ pub trait ToTrace<'tcx>: Relate<'tcx> + Copy {
}
impl<'a, 'tcx> At<'a, 'tcx> {
- /// Makes `a <: b`, where `a` may or may not be expected.
- ///
- /// See [`At::trace_exp`] and [`Trace::sub`] for a version of
- /// this method that only requires `T: Relate<'tcx>`
- pub fn sub_exp<T>(
- self,
- define_opaque_types: DefineOpaqueTypes,
- a_is_expected: bool,
- a: T,
- b: T,
- ) -> InferResult<'tcx, ()>
- where
- T: ToTrace<'tcx>,
- {
- self.trace_exp(a_is_expected, a, b).sub(define_opaque_types, a, b)
- }
-
/// Makes `actual <: expected`. For example, if type-checking a
/// call like `foo(x)`, where `foo: fn(i32)`, you might have
/// `sup(i32, x)`, since the "expected" type is the type that
@@ -138,7 +120,7 @@ impl<'a, 'tcx> At<'a, 'tcx> {
where
T: ToTrace<'tcx>,
{
- self.sub_exp(define_opaque_types, false, actual, expected)
+ self.trace(expected, actual).sup(define_opaque_types, expected, actual)
}
/// Makes `expected <: actual`.
@@ -154,24 +136,7 @@ impl<'a, 'tcx> At<'a, 'tcx> {
where
T: ToTrace<'tcx>,
{
- self.sub_exp(define_opaque_types, true, expected, actual)
- }
-
- /// Makes `expected <: actual`.
- ///
- /// See [`At::trace_exp`] and [`Trace::eq`] for a version of
- /// this method that only requires `T: Relate<'tcx>`
- pub fn eq_exp<T>(
- self,
- define_opaque_types: DefineOpaqueTypes,
- a_is_expected: bool,
- a: T,
- b: T,
- ) -> InferResult<'tcx, ()>
- where
- T: ToTrace<'tcx>,
- {
- self.trace_exp(a_is_expected, a, b).eq(define_opaque_types, a, b)
+ self.trace(expected, actual).sub(define_opaque_types, expected, actual)
}
/// Makes `expected <: actual`.
@@ -260,48 +225,50 @@ impl<'a, 'tcx> At<'a, 'tcx> {
where
T: ToTrace<'tcx>,
{
- self.trace_exp(true, expected, actual)
- }
-
- /// Like `trace`, but the expected value is determined by the
- /// boolean argument (if true, then the first argument `a` is the
- /// "expected" value).
- pub fn trace_exp<T>(self, a_is_expected: bool, a: T, b: T) -> Trace<'a, 'tcx>
- where
- T: ToTrace<'tcx>,
- {
- let trace = ToTrace::to_trace(self.cause, a_is_expected, a, b);
- Trace { at: self, trace, a_is_expected }
+ let trace = ToTrace::to_trace(self.cause, true, expected, actual);
+ Trace { at: self, trace }
}
}
impl<'a, 'tcx> Trace<'a, 'tcx> {
- /// Makes `a <: b` where `a` may or may not be expected (if
- /// `a_is_expected` is true, then `a` is expected).
+ /// Makes `a <: b`.
#[instrument(skip(self), level = "debug")]
pub fn sub<T>(self, define_opaque_types: DefineOpaqueTypes, a: T, b: T) -> InferResult<'tcx, ()>
where
T: Relate<'tcx>,
{
- let Trace { at, trace, a_is_expected } = self;
+ let Trace { at, trace } = self;
let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
fields
- .sub(a_is_expected)
+ .sub()
.relate(a, b)
.map(move |_| InferOk { value: (), obligations: fields.obligations })
}
- /// Makes `a == b`; the expectation is set by the call to
- /// `trace()`.
+ /// Makes `a :> b`.
+ #[instrument(skip(self), level = "debug")]
+ pub fn sup<T>(self, define_opaque_types: DefineOpaqueTypes, a: T, b: T) -> InferResult<'tcx, ()>
+ where
+ T: Relate<'tcx>,
+ {
+ let Trace { at, trace } = self;
+ let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
+ fields
+ .sup()
+ .relate(a, b)
+ .map(move |_| InferOk { value: (), obligations: fields.obligations })
+ }
+
+ /// Makes `a == b`.
#[instrument(skip(self), level = "debug")]
pub fn eq<T>(self, define_opaque_types: DefineOpaqueTypes, a: T, b: T) -> InferResult<'tcx, ()>
where
T: Relate<'tcx>,
{
- let Trace { at, trace, a_is_expected } = self;
+ let Trace { at, trace } = self;
let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
fields
- .equate(StructurallyRelateAliases::No, a_is_expected)
+ .equate(StructurallyRelateAliases::No)
.relate(a, b)
.map(move |_| InferOk { value: (), obligations: fields.obligations })
}
@@ -313,11 +280,11 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
where
T: Relate<'tcx>,
{
- let Trace { at, trace, a_is_expected } = self;
+ let Trace { at, trace } = self;
debug_assert!(at.infcx.next_trait_solver());
let mut fields = at.infcx.combine_fields(trace, at.param_env, DefineOpaqueTypes::No);
fields
- .equate(StructurallyRelateAliases::Yes, a_is_expected)
+ .equate(StructurallyRelateAliases::Yes)
.relate(a, b)
.map(move |_| InferOk { value: (), obligations: fields.obligations })
}
@@ -327,10 +294,10 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
where
T: Relate<'tcx>,
{
- let Trace { at, trace, a_is_expected } = self;
+ let Trace { at, trace } = self;
let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
fields
- .lub(a_is_expected)
+ .lub()
.relate(a, b)
.map(move |t| InferOk { value: t, obligations: fields.obligations })
}
@@ -340,10 +307,10 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
where
T: Relate<'tcx>,
{
- let Trace { at, trace, a_is_expected } = self;
+ let Trace { at, trace } = self;
let mut fields = at.infcx.combine_fields(trace, at.param_env, define_opaque_types);
fields
- .glb(a_is_expected)
+ .glb()
.relate(a, b)
.map(move |t| InferOk { value: t, obligations: fields.obligations })
}
diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types.rs
index d381c77ec66..07245643ef5 100644
--- a/compiler/rustc_infer/src/infer/opaque_types.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types.rs
@@ -522,13 +522,7 @@ impl<'tcx> InferCtxt<'tcx> {
) -> InferResult<'tcx, ()> {
let mut obligations = Vec::new();
- self.insert_hidden_type(
- opaque_type_key,
- &cause,
- param_env,
- hidden_ty,
- &mut obligations,
- )?;
+ self.insert_hidden_type(opaque_type_key, &cause, param_env, hidden_ty, &mut obligations)?;
self.add_item_bounds_for_hidden_type(
opaque_type_key.def_id.to_def_id(),
diff --git a/compiler/rustc_infer/src/infer/relate/combine.rs b/compiler/rustc_infer/src/infer/relate/combine.rs
index 749c50b57b5..099b7ff7c04 100644
--- a/compiler/rustc_infer/src/infer/relate/combine.rs
+++ b/compiler/rustc_infer/src/infer/relate/combine.rs
@@ -321,21 +321,24 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
pub fn equate<'a>(
&'a mut self,
structurally_relate_aliases: StructurallyRelateAliases,
- a_is_expected: bool,
) -> TypeRelating<'a, 'infcx, 'tcx> {
- TypeRelating::new(self, a_is_expected, structurally_relate_aliases, ty::Invariant)
+ TypeRelating::new(self, structurally_relate_aliases, ty::Invariant)
}
- pub fn sub<'a>(&'a mut self, a_is_expected: bool) -> TypeRelating<'a, 'infcx, 'tcx> {
- TypeRelating::new(self, a_is_expected, StructurallyRelateAliases::No, ty::Covariant)
+ pub fn sub<'a>(&'a mut self) -> TypeRelating<'a, 'infcx, 'tcx> {
+ TypeRelating::new(self, StructurallyRelateAliases::No, ty::Covariant)
}
- pub fn lub<'a>(&'a mut self, a_is_expected: bool) -> Lub<'a, 'infcx, 'tcx> {
- Lub::new(self, a_is_expected)
+ pub fn sup<'a>(&'a mut self) -> TypeRelating<'a, 'infcx, 'tcx> {
+ TypeRelating::new(self, StructurallyRelateAliases::No, ty::Contravariant)
}
- pub fn glb<'a>(&'a mut self, a_is_expected: bool) -> Glb<'a, 'infcx, 'tcx> {
- Glb::new(self, a_is_expected)
+ pub fn lub<'a>(&'a mut self) -> Lub<'a, 'infcx, 'tcx> {
+ Lub::new(self)
+ }
+
+ pub fn glb<'a>(&'a mut self) -> Glb<'a, 'infcx, 'tcx> {
+ Glb::new(self)
}
pub fn register_obligations(&mut self, obligations: PredicateObligations<'tcx>) {
diff --git a/compiler/rustc_infer/src/infer/relate/glb.rs b/compiler/rustc_infer/src/infer/relate/glb.rs
index 9b77e6888b2..f6796861b12 100644
--- a/compiler/rustc_infer/src/infer/relate/glb.rs
+++ b/compiler/rustc_infer/src/infer/relate/glb.rs
@@ -13,15 +13,11 @@ use crate::traits::{ObligationCause, PredicateObligations};
/// "Greatest lower bound" (common subtype)
pub struct Glb<'combine, 'infcx, 'tcx> {
fields: &'combine mut CombineFields<'infcx, 'tcx>,
- a_is_expected: bool,
}
impl<'combine, 'infcx, 'tcx> Glb<'combine, 'infcx, 'tcx> {
- pub fn new(
- fields: &'combine mut CombineFields<'infcx, 'tcx>,
- a_is_expected: bool,
- ) -> Glb<'combine, 'infcx, 'tcx> {
- Glb { fields, a_is_expected }
+ pub fn new(fields: &'combine mut CombineFields<'infcx, 'tcx>) -> Glb<'combine, 'infcx, 'tcx> {
+ Glb { fields }
}
}
@@ -35,7 +31,7 @@ impl<'tcx> TypeRelation<'tcx> for Glb<'_, '_, 'tcx> {
}
fn a_is_expected(&self) -> bool {
- self.a_is_expected
+ true
}
fn relate_with_variance<T: Relate<'tcx>>(
@@ -46,13 +42,11 @@ impl<'tcx> TypeRelation<'tcx> for Glb<'_, '_, 'tcx> {
b: T,
) -> RelateResult<'tcx, T> {
match variance {
- ty::Invariant => {
- self.fields.equate(StructurallyRelateAliases::No, self.a_is_expected).relate(a, b)
- }
+ ty::Invariant => self.fields.equate(StructurallyRelateAliases::No).relate(a, b),
ty::Covariant => self.relate(a, b),
// FIXME(#41044) -- not correct, need test
ty::Bivariant => Ok(a),
- ty::Contravariant => self.fields.lub(self.a_is_expected).relate(a, b),
+ ty::Contravariant => self.fields.lub().relate(a, b),
}
}
@@ -126,7 +120,7 @@ impl<'combine, 'infcx, 'tcx> LatticeDir<'infcx, 'tcx> for Glb<'combine, 'infcx,
}
fn relate_bound(&mut self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
- let mut sub = self.fields.sub(self.a_is_expected);
+ let mut sub = self.fields.sub();
sub.relate(v, a)?;
sub.relate(v, b)?;
Ok(())
diff --git a/compiler/rustc_infer/src/infer/relate/higher_ranked.rs b/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
index 90be80f67b4..c94cbb0db03 100644
--- a/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
+++ b/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
@@ -49,7 +49,13 @@ impl<'a, 'tcx> CombineFields<'a, 'tcx> {
debug!("b_prime={:?}", sup_prime);
// Compare types now that bound regions have been replaced.
- let result = self.sub(sub_is_expected).relate(sub_prime, sup_prime);
+ // Reorder the inputs so that the expected is passed first.
+ let result = if sub_is_expected {
+ self.sub().relate(sub_prime, sup_prime)
+ } else {
+ self.sup().relate(sup_prime, sub_prime)
+ };
+
if result.is_ok() {
debug!("OK result={result:?}");
}
diff --git a/compiler/rustc_infer/src/infer/relate/lub.rs b/compiler/rustc_infer/src/infer/relate/lub.rs
index db04e3231d6..3d9cfe7bf05 100644
--- a/compiler/rustc_infer/src/infer/relate/lub.rs
+++ b/compiler/rustc_infer/src/infer/relate/lub.rs
@@ -13,15 +13,11 @@ use rustc_span::Span;
/// "Least upper bound" (common supertype)
pub struct Lub<'combine, 'infcx, 'tcx> {
fields: &'combine mut CombineFields<'infcx, 'tcx>,
- a_is_expected: bool,
}
impl<'combine, 'infcx, 'tcx> Lub<'combine, 'infcx, 'tcx> {
- pub fn new(
- fields: &'combine mut CombineFields<'infcx, 'tcx>,
- a_is_expected: bool,
- ) -> Lub<'combine, 'infcx, 'tcx> {
- Lub { fields, a_is_expected }
+ pub fn new(fields: &'combine mut CombineFields<'infcx, 'tcx>) -> Lub<'combine, 'infcx, 'tcx> {
+ Lub { fields }
}
}
@@ -35,7 +31,7 @@ impl<'tcx> TypeRelation<'tcx> for Lub<'_, '_, 'tcx> {
}
fn a_is_expected(&self) -> bool {
- self.a_is_expected
+ true
}
fn relate_with_variance<T: Relate<'tcx>>(
@@ -46,13 +42,11 @@ impl<'tcx> TypeRelation<'tcx> for Lub<'_, '_, 'tcx> {
b: T,
) -> RelateResult<'tcx, T> {
match variance {
- ty::Invariant => {
- self.fields.equate(StructurallyRelateAliases::No, self.a_is_expected).relate(a, b)
- }
+ ty::Invariant => self.fields.equate(StructurallyRelateAliases::No).relate(a, b),
ty::Covariant => self.relate(a, b),
// FIXME(#41044) -- not correct, need test
ty::Bivariant => Ok(a),
- ty::Contravariant => self.fields.glb(self.a_is_expected).relate(a, b),
+ ty::Contravariant => self.fields.glb().relate(a, b),
}
}
@@ -126,7 +120,7 @@ impl<'combine, 'infcx, 'tcx> LatticeDir<'infcx, 'tcx> for Lub<'combine, 'infcx,
}
fn relate_bound(&mut self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()> {
- let mut sub = self.fields.sub(self.a_is_expected);
+ let mut sub = self.fields.sub();
sub.relate(a, v)?;
sub.relate(b, v)?;
Ok(())
diff --git a/compiler/rustc_infer/src/infer/relate/type_relating.rs b/compiler/rustc_infer/src/infer/relate/type_relating.rs
index ddc4bf9a514..7464b525724 100644
--- a/compiler/rustc_infer/src/infer/relate/type_relating.rs
+++ b/compiler/rustc_infer/src/infer/relate/type_relating.rs
@@ -12,7 +12,6 @@ use rustc_span::Span;
/// Enforce that `a` is equal to or a subtype of `b`.
pub struct TypeRelating<'combine, 'a, 'tcx> {
fields: &'combine mut CombineFields<'a, 'tcx>,
- a_is_expected: bool,
structurally_relate_aliases: StructurallyRelateAliases,
ambient_variance: ty::Variance,
}
@@ -20,11 +19,10 @@ pub struct TypeRelating<'combine, 'a, 'tcx> {
impl<'combine, 'infcx, 'tcx> TypeRelating<'combine, 'infcx, 'tcx> {
pub fn new(
f: &'combine mut CombineFields<'infcx, 'tcx>,
- a_is_expected: bool,
structurally_relate_aliases: StructurallyRelateAliases,
ambient_variance: ty::Variance,
) -> TypeRelating<'combine, 'infcx, 'tcx> {
- TypeRelating { fields: f, a_is_expected, structurally_relate_aliases, ambient_variance }
+ TypeRelating { fields: f, structurally_relate_aliases, ambient_variance }
}
}
@@ -38,7 +36,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
}
fn a_is_expected(&self) -> bool {
- self.a_is_expected
+ true
}
fn relate_with_variance<T: Relate<'tcx>>(
@@ -79,7 +77,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
self.fields.trace.cause.clone(),
self.fields.param_env,
ty::Binder::dummy(ty::PredicateKind::Subtype(ty::SubtypePredicate {
- a_is_expected: self.a_is_expected,
+ a_is_expected: true,
a,
b,
})),
@@ -93,7 +91,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
self.fields.trace.cause.clone(),
self.fields.param_env,
ty::Binder::dummy(ty::PredicateKind::Subtype(ty::SubtypePredicate {
- a_is_expected: !self.a_is_expected,
+ a_is_expected: false,
a: b,
b: a,
})),
@@ -109,18 +107,12 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
}
(&ty::Infer(TyVar(a_vid)), _) => {
- infcx.instantiate_ty_var(
- self,
- self.a_is_expected,
- a_vid,
- self.ambient_variance,
- b,
- )?;
+ infcx.instantiate_ty_var(self, true, a_vid, self.ambient_variance, b)?;
}
(_, &ty::Infer(TyVar(b_vid))) => {
infcx.instantiate_ty_var(
self,
- !self.a_is_expected,
+ false,
b_vid,
self.ambient_variance.xform(ty::Contravariant),
a,
@@ -147,13 +139,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
{
self.fields.obligations.extend(
infcx
- .handle_opaque_type(
- a,
- b,
- self.a_is_expected,
- &self.fields.trace.cause,
- self.param_env(),
- )?
+ .handle_opaque_type(a, b, true, &self.fields.trace.cause, self.param_env())?
.obligations,
);
}
@@ -239,14 +225,14 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
} else {
match self.ambient_variance {
ty::Covariant => {
- self.fields.higher_ranked_sub(a, b, self.a_is_expected)?;
+ self.fields.higher_ranked_sub(a, b, true)?;
}
ty::Contravariant => {
- self.fields.higher_ranked_sub(b, a, !self.a_is_expected)?;
+ self.fields.higher_ranked_sub(b, a, false)?;
}
ty::Invariant => {
- self.fields.higher_ranked_sub(a, b, self.a_is_expected)?;
- self.fields.higher_ranked_sub(b, a, !self.a_is_expected)?;
+ self.fields.higher_ranked_sub(a, b, true)?;
+ self.fields.higher_ranked_sub(b, a, false)?;
}
ty::Bivariant => {
unreachable!("Expected bivariance to be handled in relate_with_variance")
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
index fa8edd11594..7f7bd867f63 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
@@ -1541,12 +1541,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
// since the normalization is just done to improve the error message.
let _ = ocx.select_where_possible();
- if let Err(new_err) = ocx.eq(
- &obligation.cause,
- obligation.param_env,
- expected,
- actual,
- ) {
+ if let Err(new_err) =
+ ocx.eq(&obligation.cause, obligation.param_env, expected, actual)
+ {
(Some((data, is_normalized_term_expected, normalized_term, data.term)), new_err)
} else {
(None, error.err)
From b1536568db8890c2e9b7ecae30f26ab7d74219ff Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 28 Feb 2024 17:41:18 +0000
Subject: [PATCH 6/7] Fallout from removing a_is_expected
---
.../src/type_check/relate_tys.rs | 7 +-
.../src/infer/error_reporting/mod.rs | 4 -
.../rustc_infer/src/infer/opaque_types.rs | 6 +-
.../src/infer/outlives/test_type_match.rs | 4 -
.../rustc_infer/src/infer/relate/combine.rs | 31 +++-----
.../src/infer/relate/generalize.rs | 12 +--
compiler/rustc_infer/src/infer/relate/glb.rs | 4 -
.../rustc_infer/src/infer/relate/lattice.rs | 4 +-
compiler/rustc_infer/src/infer/relate/lub.rs | 4 -
.../src/infer/relate/type_relating.rs | 11 +--
compiler/rustc_middle/src/ty/_match.rs | 8 +-
compiler/rustc_middle/src/ty/relate.rs | 78 ++++++-------------
12 files changed, 46 insertions(+), 127 deletions(-)
diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
index 5c5274d7d86..78609a482ed 100644
--- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs
+++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
@@ -160,8 +160,7 @@ impl<'me, 'bccx, 'tcx> NllTypeRelating<'me, 'bccx, 'tcx> {
),
};
let cause = ObligationCause::dummy_with_span(self.span());
- let obligations =
- infcx.handle_opaque_type(a, b, true, &cause, self.param_env())?.obligations;
+ let obligations = infcx.handle_opaque_type(a, b, &cause, self.param_env())?.obligations;
self.register_obligations(obligations);
Ok(())
}
@@ -330,10 +329,6 @@ impl<'bccx, 'tcx> TypeRelation<'tcx> for NllTypeRelating<'_, 'bccx, 'tcx> {
"nll::subtype"
}
- fn a_is_expected(&self) -> bool {
- true
- }
-
#[instrument(skip(self, info), level = "trace", ret)]
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 911b2f16c8b..1cf990fef04 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -2654,10 +2654,6 @@ impl<'tcx> TypeRelation<'tcx> for SameTypeModuloInfer<'_, 'tcx> {
"SameTypeModuloInfer"
}
- fn a_is_expected(&self) -> bool {
- true
- }
-
fn relate_with_variance<T: relate::Relate<'tcx>>(
&mut self,
_variance: ty::Variance,
diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types.rs
index 07245643ef5..7a789a1b41b 100644
--- a/compiler/rustc_infer/src/infer/opaque_types.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types.rs
@@ -78,9 +78,7 @@ impl<'tcx> InferCtxt<'tcx> {
span,
});
obligations.extend(
- self.handle_opaque_type(ty, ty_var, true, &cause, param_env)
- .unwrap()
- .obligations,
+ self.handle_opaque_type(ty, ty_var, &cause, param_env).unwrap().obligations,
);
ty_var
}
@@ -94,14 +92,12 @@ impl<'tcx> InferCtxt<'tcx> {
&self,
a: Ty<'tcx>,
b: Ty<'tcx>,
- a_is_expected: bool,
cause: &ObligationCause<'tcx>,
param_env: ty::ParamEnv<'tcx>,
) -> InferResult<'tcx, ()> {
if a.references_error() || b.references_error() {
return Ok(InferOk { value: (), obligations: vec![] });
}
- let (a, b) = if a_is_expected { (a, b) } else { (b, a) };
let process = |a: Ty<'tcx>, b: Ty<'tcx>| match *a.kind() {
ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) if def_id.is_local() => {
let def_id = def_id.expect_local();
diff --git a/compiler/rustc_infer/src/infer/outlives/test_type_match.rs b/compiler/rustc_infer/src/infer/outlives/test_type_match.rs
index d547f51f381..29c11d4247d 100644
--- a/compiler/rustc_infer/src/infer/outlives/test_type_match.rs
+++ b/compiler/rustc_infer/src/infer/outlives/test_type_match.rs
@@ -144,10 +144,6 @@ impl<'tcx> TypeRelation<'tcx> for MatchAgainstHigherRankedOutlives<'tcx> {
self.tcx
}
- fn a_is_expected(&self) -> bool {
- true
- } // irrelevant
-
#[instrument(level = "trace", skip(self))]
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
diff --git a/compiler/rustc_infer/src/infer/relate/combine.rs b/compiler/rustc_infer/src/infer/relate/combine.rs
index 099b7ff7c04..28b7db275a3 100644
--- a/compiler/rustc_infer/src/infer/relate/combine.rs
+++ b/compiler/rustc_infer/src/infer/relate/combine.rs
@@ -17,12 +17,6 @@
//!
//! On success, the LUB/GLB operations return the appropriate bound. The
//! return value of `Equate` or `Sub` shouldn't really be used.
-//!
-//! ## Contravariance
-//!
-//! We explicitly track which argument is expected using
-//! [TypeRelation::a_is_expected], so when dealing with contravariance
-//! this should be correctly updated.
use super::glb::Glb;
use super::lub::Lub;
@@ -57,7 +51,6 @@ impl<'tcx> InferCtxt<'tcx> {
where
R: ObligationEmittingRelation<'tcx>,
{
- let a_is_expected = relation.a_is_expected();
debug_assert!(!a.has_escaping_bound_vars());
debug_assert!(!b.has_escaping_bound_vars());
@@ -68,20 +61,20 @@ impl<'tcx> InferCtxt<'tcx> {
.borrow_mut()
.int_unification_table()
.unify_var_var(a_id, b_id)
- .map_err(|e| int_unification_error(a_is_expected, e))?;
+ .map_err(|e| int_unification_error(true, e))?;
Ok(a)
}
(&ty::Infer(ty::IntVar(v_id)), &ty::Int(v)) => {
- self.unify_integral_variable(a_is_expected, v_id, IntType(v))
+ self.unify_integral_variable(true, v_id, IntType(v))
}
(&ty::Int(v), &ty::Infer(ty::IntVar(v_id))) => {
- self.unify_integral_variable(!a_is_expected, v_id, IntType(v))
+ self.unify_integral_variable(false, v_id, IntType(v))
}
(&ty::Infer(ty::IntVar(v_id)), &ty::Uint(v)) => {
- self.unify_integral_variable(a_is_expected, v_id, UintType(v))
+ self.unify_integral_variable(true, v_id, UintType(v))
}
(&ty::Uint(v), &ty::Infer(ty::IntVar(v_id))) => {
- self.unify_integral_variable(!a_is_expected, v_id, UintType(v))
+ self.unify_integral_variable(false, v_id, UintType(v))
}
// Relate floating-point variables to other types
@@ -90,14 +83,14 @@ impl<'tcx> InferCtxt<'tcx> {
.borrow_mut()
.float_unification_table()
.unify_var_var(a_id, b_id)
- .map_err(|e| float_unification_error(a_is_expected, e))?;
+ .map_err(|e| float_unification_error(true, e))?;
Ok(a)
}
(&ty::Infer(ty::FloatVar(v_id)), &ty::Float(v)) => {
- self.unify_float_variable(a_is_expected, v_id, v)
+ self.unify_float_variable(true, v_id, v)
}
(&ty::Float(v), &ty::Infer(ty::FloatVar(v_id))) => {
- self.unify_float_variable(!a_is_expected, v_id, v)
+ self.unify_float_variable(false, v_id, v)
}
// We don't expect `TyVar` or `Fresh*` vars at this point with lazy norm.
@@ -130,7 +123,7 @@ impl<'tcx> InferCtxt<'tcx> {
// All other cases of inference are errors
(&ty::Infer(_), _) | (_, &ty::Infer(_)) => {
- Err(TypeError::Sorts(ty::relate::expected_found(relation, a, b)))
+ Err(TypeError::Sorts(ty::relate::expected_found(a, b)))
}
// During coherence, opaque types should be treated as *possibly*
@@ -228,12 +221,12 @@ impl<'tcx> InferCtxt<'tcx> {
}
(ty::ConstKind::Infer(InferConst::Var(vid)), _) => {
- self.instantiate_const_var(relation, relation.a_is_expected(), vid, b)?;
+ self.instantiate_const_var(relation, true, vid, b)?;
Ok(b)
}
(_, ty::ConstKind::Infer(InferConst::Var(vid))) => {
- self.instantiate_const_var(relation, !relation.a_is_expected(), vid, a)?;
+ self.instantiate_const_var(relation, false, vid, a)?;
Ok(a)
}
@@ -250,8 +243,6 @@ impl<'tcx> InferCtxt<'tcx> {
{
match relation.structurally_relate_aliases() {
StructurallyRelateAliases::No => {
- let (a, b) = if relation.a_is_expected() { (a, b) } else { (b, a) };
-
relation.register_predicates([if self.next_trait_solver() {
ty::PredicateKind::AliasRelate(
a.into(),
diff --git a/compiler/rustc_infer/src/infer/relate/generalize.rs b/compiler/rustc_infer/src/infer/relate/generalize.rs
index b18c8a8b844..5fb9d9341e0 100644
--- a/compiler/rustc_infer/src/infer/relate/generalize.rs
+++ b/compiler/rustc_infer/src/infer/relate/generalize.rs
@@ -130,7 +130,7 @@ impl<'tcx> InferCtxt<'tcx> {
// instantiate_ty_var(?b, A) # expected and variance flipped
// A rel A'
// ```
- if target_is_expected == relation.a_is_expected() {
+ if target_is_expected {
relation.relate(generalized_ty, source_ty)?;
} else {
debug!("flip relation");
@@ -204,9 +204,9 @@ impl<'tcx> InferCtxt<'tcx> {
.const_unification_table()
.union_value(target_vid, ConstVariableValue::Known { value: generalized_ct });
- // HACK: make sure that we `a_is_expected` continues to be
- // correct when relating the generalized type with the source.
- if target_is_expected == relation.a_is_expected() {
+ // Make sure that the order is correct when relating the
+ // generalized const and the source.
+ if target_is_expected {
relation.relate_with_variance(
ty::Variance::Invariant,
ty::VarianceDiagInfo::default(),
@@ -398,10 +398,6 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
"Generalizer"
}
- fn a_is_expected(&self) -> bool {
- true
- }
-
fn relate_item_args(
&mut self,
item_def_id: DefId,
diff --git a/compiler/rustc_infer/src/infer/relate/glb.rs b/compiler/rustc_infer/src/infer/relate/glb.rs
index f6796861b12..b86d1b2671d 100644
--- a/compiler/rustc_infer/src/infer/relate/glb.rs
+++ b/compiler/rustc_infer/src/infer/relate/glb.rs
@@ -30,10 +30,6 @@ impl<'tcx> TypeRelation<'tcx> for Glb<'_, '_, 'tcx> {
self.fields.tcx()
}
- fn a_is_expected(&self) -> bool {
- true
- }
-
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
diff --git a/compiler/rustc_infer/src/infer/relate/lattice.rs b/compiler/rustc_infer/src/infer/relate/lattice.rs
index 744e2dfa380..747158585db 100644
--- a/compiler/rustc_infer/src/infer/relate/lattice.rs
+++ b/compiler/rustc_infer/src/infer/relate/lattice.rs
@@ -116,9 +116,7 @@ where
&& !this.infcx().next_trait_solver() =>
{
this.register_obligations(
- infcx
- .handle_opaque_type(a, b, this.a_is_expected(), this.cause(), this.param_env())?
- .obligations,
+ infcx.handle_opaque_type(a, b, this.cause(), this.param_env())?.obligations,
);
Ok(a)
}
diff --git a/compiler/rustc_infer/src/infer/relate/lub.rs b/compiler/rustc_infer/src/infer/relate/lub.rs
index 3d9cfe7bf05..20f5f65c984 100644
--- a/compiler/rustc_infer/src/infer/relate/lub.rs
+++ b/compiler/rustc_infer/src/infer/relate/lub.rs
@@ -30,10 +30,6 @@ impl<'tcx> TypeRelation<'tcx> for Lub<'_, '_, 'tcx> {
self.fields.tcx()
}
- fn a_is_expected(&self) -> bool {
- true
- }
-
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
diff --git a/compiler/rustc_infer/src/infer/relate/type_relating.rs b/compiler/rustc_infer/src/infer/relate/type_relating.rs
index 7464b525724..c053adc5e07 100644
--- a/compiler/rustc_infer/src/infer/relate/type_relating.rs
+++ b/compiler/rustc_infer/src/infer/relate/type_relating.rs
@@ -35,10 +35,6 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
self.fields.infcx.tcx
}
- fn a_is_expected(&self) -> bool {
- true
- }
-
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
@@ -139,7 +135,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
{
self.fields.obligations.extend(
infcx
- .handle_opaque_type(a, b, true, &self.fields.trace.cause, self.param_env())?
+ .handle_opaque_type(a, b, &self.fields.trace.cause, self.param_env())?
.obligations,
);
}
@@ -158,10 +154,6 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
b: ty::Region<'tcx>,
) -> RelateResult<'tcx, ty::Region<'tcx>> {
debug!("{}.regions({:?}, {:?})", self.tag(), a, b);
-
- // FIXME -- we have more fine-grained information available
- // from the "cause" field, we could perhaps give more tailored
- // error messages.
let origin = SubregionOrigin::Subtype(Box::new(self.fields.trace.clone()));
match self.ambient_variance {
@@ -184,7 +176,6 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
.make_subregion(origin, a, b);
}
ty::Invariant => {
- // The order of `make_eqregion` apparently matters.
self.fields
.infcx
.inner
diff --git a/compiler/rustc_middle/src/ty/_match.rs b/compiler/rustc_middle/src/ty/_match.rs
index 425a2dbd890..e28e4d66faf 100644
--- a/compiler/rustc_middle/src/ty/_match.rs
+++ b/compiler/rustc_middle/src/ty/_match.rs
@@ -37,10 +37,6 @@ impl<'tcx> TypeRelation<'tcx> for MatchAgainstFreshVars<'tcx> {
self.tcx
}
- fn a_is_expected(&self) -> bool {
- true
- } // irrelevant
-
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
_: ty::Variance,
@@ -75,7 +71,7 @@ impl<'tcx> TypeRelation<'tcx> for MatchAgainstFreshVars<'tcx> {
) => Ok(a),
(&ty::Infer(_), _) | (_, &ty::Infer(_)) => {
- Err(TypeError::Sorts(relate::expected_found(self, a, b)))
+ Err(TypeError::Sorts(relate::expected_found(a, b)))
}
(&ty::Error(guar), _) | (_, &ty::Error(guar)) => Ok(Ty::new_error(self.tcx(), guar)),
@@ -100,7 +96,7 @@ impl<'tcx> TypeRelation<'tcx> for MatchAgainstFreshVars<'tcx> {
}
(ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => {
- return Err(TypeError::ConstMismatch(relate::expected_found(self, a, b)));
+ return Err(TypeError::ConstMismatch(relate::expected_found(a, b)));
}
_ => {}
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index abd39914cfd..990e78aff8a 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -15,21 +15,12 @@ use std::iter;
pub type RelateResult<'tcx, T> = Result<T, TypeError<'tcx>>;
-#[derive(Clone, Debug)]
-pub enum Cause {
- ExistentialRegionBound, // relating an existential region bound
-}
-
pub trait TypeRelation<'tcx>: Sized {
fn tcx(&self) -> TyCtxt<'tcx>;
/// Returns a static string we can use for printouts.
fn tag(&self) -> &'static str;
- /// Returns `true` if the value `a` is the "expected" type in the
- /// relation. Just affects error messages.
- fn a_is_expected(&self) -> bool;
-
/// Generic relation routine suitable for most anything.
fn relate<T: Relate<'tcx>>(&mut self, a: T, b: T) -> RelateResult<'tcx, T> {
Relate::relate(self, a, b)
@@ -171,11 +162,7 @@ impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
let tcx = relation.tcx();
if a.c_variadic != b.c_variadic {
- return Err(TypeError::VariadicMismatch(expected_found(
- relation,
- a.c_variadic,
- b.c_variadic,
- )));
+ return Err(TypeError::VariadicMismatch(expected_found(a.c_variadic, b.c_variadic)));
}
let unsafety = relation.relate(a.unsafety, b.unsafety)?;
let abi = relation.relate(a.abi, b.abi)?;
@@ -220,39 +207,31 @@ impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
impl<'tcx> Relate<'tcx> for ty::BoundConstness {
fn relate<R: TypeRelation<'tcx>>(
- relation: &mut R,
+ _relation: &mut R,
a: ty::BoundConstness,
b: ty::BoundConstness,
) -> RelateResult<'tcx, ty::BoundConstness> {
- if a != b {
- Err(TypeError::ConstnessMismatch(expected_found(relation, a, b)))
- } else {
- Ok(a)
- }
+ if a != b { Err(TypeError::ConstnessMismatch(expected_found(a, b))) } else { Ok(a) }
}
}
impl<'tcx> Relate<'tcx> for hir::Unsafety {
fn relate<R: TypeRelation<'tcx>>(
- relation: &mut R,
+ _relation: &mut R,
a: hir::Unsafety,
b: hir::Unsafety,
) -> RelateResult<'tcx, hir::Unsafety> {
- if a != b {
- Err(TypeError::UnsafetyMismatch(expected_found(relation, a, b)))
- } else {
- Ok(a)
- }
+ if a != b { Err(TypeError::UnsafetyMismatch(expected_found(a, b))) } else { Ok(a) }
}
}
impl<'tcx> Relate<'tcx> for abi::Abi {
fn relate<R: TypeRelation<'tcx>>(
- relation: &mut R,
+ _relation: &mut R,
a: abi::Abi,
b: abi::Abi,
) -> RelateResult<'tcx, abi::Abi> {
- if a == b { Ok(a) } else { Err(TypeError::AbiMismatch(expected_found(relation, a, b))) }
+ if a == b { Ok(a) } else { Err(TypeError::AbiMismatch(expected_found(a, b))) }
}
}
@@ -263,7 +242,7 @@ impl<'tcx> Relate<'tcx> for ty::AliasTy<'tcx> {
b: ty::AliasTy<'tcx>,
) -> RelateResult<'tcx, ty::AliasTy<'tcx>> {
if a.def_id != b.def_id {
- Err(TypeError::ProjectionMismatched(expected_found(relation, a.def_id, b.def_id)))
+ Err(TypeError::ProjectionMismatched(expected_found(a.def_id, b.def_id)))
} else {
let args = match relation.tcx().def_kind(a.def_id) {
DefKind::OpaqueTy => relate_args_with_variances(
@@ -291,7 +270,7 @@ impl<'tcx> Relate<'tcx> for ty::ExistentialProjection<'tcx> {
b: ty::ExistentialProjection<'tcx>,
) -> RelateResult<'tcx, ty::ExistentialProjection<'tcx>> {
if a.def_id != b.def_id {
- Err(TypeError::ProjectionMismatched(expected_found(relation, a.def_id, b.def_id)))
+ Err(TypeError::ProjectionMismatched(expected_found(a.def_id, b.def_id)))
} else {
let term = relation.relate_with_variance(
ty::Invariant,
@@ -318,7 +297,7 @@ impl<'tcx> Relate<'tcx> for ty::TraitRef<'tcx> {
) -> RelateResult<'tcx, ty::TraitRef<'tcx>> {
// Different traits cannot be related.
if a.def_id != b.def_id {
- Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id)))
+ Err(TypeError::Traits(expected_found(a.def_id, b.def_id)))
} else {
let args = relate_args_invariantly(relation, a.args, b.args)?;
Ok(ty::TraitRef::new(relation.tcx(), a.def_id, args))
@@ -334,7 +313,7 @@ impl<'tcx> Relate<'tcx> for ty::ExistentialTraitRef<'tcx> {
) -> RelateResult<'tcx, ty::ExistentialTraitRef<'tcx>> {
// Different traits cannot be related.
if a.def_id != b.def_id {
- Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id)))
+ Err(TypeError::Traits(expected_found(a.def_id, b.def_id)))
} else {
let args = relate_args_invariantly(relation, a.args, b.args)?;
Ok(ty::ExistentialTraitRef { def_id: a.def_id, args })
@@ -510,9 +489,9 @@ pub fn structurally_relate_tys<'tcx, R: TypeRelation<'tcx>>(
let sz_b = sz_b.try_to_target_usize(tcx);
match (sz_a, sz_b) {
- (Some(sz_a_val), Some(sz_b_val)) if sz_a_val != sz_b_val => Err(
- TypeError::FixedArraySize(expected_found(relation, sz_a_val, sz_b_val)),
- ),
+ (Some(sz_a_val), Some(sz_b_val)) if sz_a_val != sz_b_val => {
+ Err(TypeError::FixedArraySize(expected_found(sz_a_val, sz_b_val)))
+ }
_ => Err(err),
}
}
@@ -531,9 +510,9 @@ pub fn structurally_relate_tys<'tcx, R: TypeRelation<'tcx>>(
iter::zip(as_, bs).map(|(a, b)| relation.relate(a, b)),
)?)
} else if !(as_.is_empty() || bs.is_empty()) {
- Err(TypeError::TupleSize(expected_found(relation, as_.len(), bs.len())))
+ Err(TypeError::TupleSize(expected_found(as_.len(), bs.len())))
} else {
- Err(TypeError::Sorts(expected_found(relation, a, b)))
+ Err(TypeError::Sorts(expected_found(a, b)))
}
}
@@ -554,7 +533,7 @@ pub fn structurally_relate_tys<'tcx, R: TypeRelation<'tcx>>(
Ok(Ty::new_alias(tcx, a_kind, alias_ty))
}
- _ => Err(TypeError::Sorts(expected_found(relation, a, b))),
+ _ => Err(TypeError::Sorts(expected_found(a, b))),
}
}
@@ -652,13 +631,13 @@ pub fn structurally_relate_consts<'tcx, R: TypeRelation<'tcx>>(
let related_args = tcx.mk_const_list(&related_args);
Expr::FunctionCall(func, related_args)
}
- _ => return Err(TypeError::ConstMismatch(expected_found(r, a, b))),
+ _ => return Err(TypeError::ConstMismatch(expected_found(a, b))),
};
return Ok(ty::Const::new_expr(tcx, expr, a.ty()));
}
_ => false,
};
- if is_match { Ok(a) } else { Err(TypeError::ConstMismatch(expected_found(relation, a, b))) }
+ if is_match { Ok(a) } else { Err(TypeError::ConstMismatch(expected_found(a, b))) }
}
impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
@@ -680,7 +659,7 @@ impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
b_v.sort_by(|a, b| a.skip_binder().stable_cmp(tcx, &b.skip_binder()));
b_v.dedup();
if a_v.len() != b_v.len() {
- return Err(TypeError::ExistentialMismatch(expected_found(relation, a, b)));
+ return Err(TypeError::ExistentialMismatch(expected_found(a, b)));
}
let v = iter::zip(a_v, b_v).map(|(ep_a, ep_b)| {
@@ -692,7 +671,7 @@ impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>> {
relation.relate(ep_a.rebind(a), ep_b.rebind(b))?.skip_binder(),
))),
(AutoTrait(a), AutoTrait(b)) if a == b => Ok(ep_a.rebind(AutoTrait(a))),
- _ => Err(TypeError::ExistentialMismatch(expected_found(relation, a, b))),
+ _ => Err(TypeError::ExistentialMismatch(expected_found(a, b))),
}
});
tcx.mk_poly_existential_predicates_from_iter(v)
@@ -792,15 +771,11 @@ impl<'tcx> Relate<'tcx> for GenericArg<'tcx> {
impl<'tcx> Relate<'tcx> for ty::ImplPolarity {
fn relate<R: TypeRelation<'tcx>>(
- relation: &mut R,
+ _relation: &mut R,
a: ty::ImplPolarity,
b: ty::ImplPolarity,
) -> RelateResult<'tcx, ty::ImplPolarity> {
- if a != b {
- Err(TypeError::PolarityMismatch(expected_found(relation, a, b)))
- } else {
- Ok(a)
- }
+ if a != b { Err(TypeError::PolarityMismatch(expected_found(a, b))) } else { Ok(a) }
}
}
@@ -834,9 +809,6 @@ impl<'tcx> Relate<'tcx> for Term<'tcx> {
///////////////////////////////////////////////////////////////////////////
// Error handling
-pub fn expected_found<'tcx, R, T>(relation: &mut R, a: T, b: T) -> ExpectedFound<T>
-where
- R: TypeRelation<'tcx>,
-{
- ExpectedFound::new(relation.a_is_expected(), a, b)
+pub fn expected_found<T>(a: T, b: T) -> ExpectedFound<T> {
+ ExpectedFound::new(true, a, b)
}
From 5072b659ffd502a099535342698a39f4acf8a32e Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Fri, 1 Mar 2024 01:20:11 +0000
Subject: [PATCH 7/7] Rebase fallout from TypeRelating::binders, inline
higher_ranked_sub
---
.../src/infer/relate/higher_ranked.rs | 65 +------------------
.../src/infer/relate/type_relating.rs | 52 +++++++++++++--
2 files changed, 51 insertions(+), 66 deletions(-)
diff --git a/compiler/rustc_infer/src/infer/relate/higher_ranked.rs b/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
index c94cbb0db03..f30e366c198 100644
--- a/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
+++ b/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
@@ -1,70 +1,11 @@
//! Helper routines for higher-ranked things. See the `doc` module at
//! the end of the file for details.
-use super::combine::CombineFields;
use crate::infer::CombinedSnapshot;
-use crate::infer::{HigherRankedType, InferCtxt};
+use crate::infer::InferCtxt;
use rustc_middle::ty::fold::FnMutDelegate;
-use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation};
-use rustc_middle::ty::{self, Binder, Ty, TyCtxt, TypeFoldable};
-
-impl<'a, 'tcx> CombineFields<'a, 'tcx> {
- /// Checks whether `for<..> sub <: for<..> sup` holds.
- ///
- /// For this to hold, **all** instantiations of the super type
- /// have to be a super type of **at least one** instantiation of
- /// the subtype.
- ///
- /// This is implemented by first entering a new universe.
- /// We then replace all bound variables in `sup` with placeholders,
- /// and all bound variables in `sub` with inference vars.
- /// We can then just relate the two resulting types as normal.
- ///
- /// Note: this is a subtle algorithm. For a full explanation, please see
- /// the [rustc dev guide][rd]
- ///
- /// [rd]: https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/placeholders_and_universes.html
- #[instrument(skip(self), level = "debug")]
- pub fn higher_ranked_sub<T>(
- &mut self,
- sub: Binder<'tcx, T>,
- sup: Binder<'tcx, T>,
- sub_is_expected: bool,
- ) -> RelateResult<'tcx, ()>
- where
- T: Relate<'tcx>,
- {
- let span = self.trace.cause.span;
- // First, we instantiate each bound region in the supertype with a
- // fresh placeholder region. Note that this automatically creates
- // a new universe if needed.
- self.infcx.enter_forall(sup, |sup_prime| {
- // Next, we instantiate each bound region in the subtype
- // with a fresh region variable. These region variables --
- // but no other preexisting region variables -- can name
- // the placeholders.
- let sub_prime =
- self.infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, sub);
- debug!("a_prime={:?}", sub_prime);
- debug!("b_prime={:?}", sup_prime);
-
- // Compare types now that bound regions have been replaced.
- // Reorder the inputs so that the expected is passed first.
- let result = if sub_is_expected {
- self.sub().relate(sub_prime, sup_prime)
- } else {
- self.sup().relate(sup_prime, sub_prime)
- };
-
- if result.is_ok() {
- debug!("OK result={result:?}");
- }
- // NOTE: returning the result here would be dangerous as it contains
- // placeholders which **must not** be named afterwards.
- result.map(|_| ())
- })
- }
-}
+use rustc_middle::ty::relate::RelateResult;
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
impl<'tcx> InferCtxt<'tcx> {
/// Replaces all bound variables (lifetimes, types, and constants) bound by
diff --git a/compiler/rustc_infer/src/infer/relate/type_relating.rs b/compiler/rustc_infer/src/infer/relate/type_relating.rs
index c053adc5e07..18822351f4f 100644
--- a/compiler/rustc_infer/src/infer/relate/type_relating.rs
+++ b/compiler/rustc_infer/src/infer/relate/type_relating.rs
@@ -1,4 +1,5 @@
use super::combine::CombineFields;
+use crate::infer::BoundRegionConversionTime::HigherRankedType;
use crate::infer::{
DefineOpaqueTypes, ObligationEmittingRelation, StructurallyRelateAliases, SubregionOrigin,
};
@@ -214,16 +215,59 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
{
self.relate(a, b)?;
} else {
+ let span = self.fields.trace.cause.span;
+ let infcx = self.fields.infcx;
+
match self.ambient_variance {
+ // Checks whether `for<..> sub <: for<..> sup` holds.
+ //
+ // For this to hold, **all** instantiations of the super type
+ // have to be a super type of **at least one** instantiation of
+ // the subtype.
+ //
+ // This is implemented by first entering a new universe.
+ // We then replace all bound variables in `sup` with placeholders,
+ // and all bound variables in `sub` with inference vars.
+ // We can then just relate the two resulting types as normal.
+ //
+ // Note: this is a subtle algorithm. For a full explanation, please see
+ // the [rustc dev guide][rd]
+ //
+ // [rd]: https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/placeholders_and_universes.html
ty::Covariant => {
- self.fields.higher_ranked_sub(a, b, true)?;
+ infcx.enter_forall(b, |b| {
+ let a = infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, a);
+ self.relate(a, b)
+ })?;
}
ty::Contravariant => {
- self.fields.higher_ranked_sub(b, a, false)?;
+ infcx.enter_forall(a, |a| {
+ let b = infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, b);
+ self.relate(a, b)
+ })?;
}
+
+ // When **equating** binders, we check that there is a 1-to-1
+ // correspondence between the bound vars in both types.
+ //
+ // We do so by separately instantiating one of the binders with
+ // placeholders and the other with inference variables and then
+ // equating the instantiated types.
+ //
+ // We want `for<..> A == for<..> B` -- therefore we want
+ // `exists<..> A == for<..> B` and `exists<..> B == for<..> A`.
+ // Check if `exists<..> A == for<..> B`
ty::Invariant => {
- self.fields.higher_ranked_sub(a, b, true)?;
- self.fields.higher_ranked_sub(b, a, false)?;
+ infcx.enter_forall(b, |b| {
+ let a = infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, a);
+ self.relate(a, b)
+ })?;
+
+ // Check if `exists<..> B == for<..> A`.
+ infcx.enter_forall(a, |a| {
+ let b = infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, b);
+ self.relate(a, b)
+ })?;
}
ty::Bivariant => {
unreachable!("Expected bivariance to be handled in relate_with_variance")