Rename some things

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -1,6 +1,6 @@
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::ErrorGuaranteed;
-use rustc_infer::infer::relate::{ObligationEmittingRelation, StructurallyRelateAliases};
+use rustc_infer::infer::relate::{PredicateEmittingRelation, StructurallyRelateAliases};
 use rustc_infer::infer::relate::{Relate, RelateResult, TypeRelation};
 use rustc_infer::infer::NllRegionVariableOrigin;
 use rustc_infer::traits::solve::Goal;
@@ -155,7 +155,7 @@ impl<'me, 'bccx, 'tcx> NllTypeRelating<'me, 'bccx, 'tcx> {
             ),
         };
         let cause = ObligationCause::dummy_with_span(self.span());
-        self.register_obligations(
+        self.register_goals(
             infcx
                 .handle_opaque_type(a, b, &cause, self.param_env())?
                 .obligations
@@ -539,7 +539,7 @@ impl<'bccx, 'tcx> TypeRelation<TyCtxt<'tcx>> for NllTypeRelating<'_, 'bccx, 'tcx
     }
 }
 
-impl<'bccx, 'tcx> ObligationEmittingRelation<'tcx> for NllTypeRelating<'_, 'bccx, 'tcx> {
+impl<'bccx, 'tcx> PredicateEmittingRelation<'tcx> for NllTypeRelating<'_, 'bccx, 'tcx> {
     fn span(&self) -> Span {
         self.locations.span(self.type_checker.body)
     }
@@ -558,12 +558,12 @@ impl<'bccx, 'tcx> ObligationEmittingRelation<'tcx> for NllTypeRelating<'_, 'bccx
     ) {
         let tcx = self.tcx();
         let param_env = self.param_env();
-        self.register_obligations(
+        self.register_goals(
             obligations.into_iter().map(|to_pred| Goal::new(tcx, param_env, to_pred)),
         );
     }
 
-    fn register_obligations(
+    fn register_goals(
         &mut self,
         obligations: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
     ) {
@@ -589,7 +589,7 @@ impl<'bccx, 'tcx> ObligationEmittingRelation<'tcx> for NllTypeRelating<'_, 'bccx
         );
     }
 
-    fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
+    fn register_alias_relate_predicate(&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(),

compiler/rustc_infer/src/infer/at.rs

@@ -165,7 +165,7 @@ impl<'a, 'tcx> At<'a, 'tcx> {
         Ok(InferOk {
             value: (),
             obligations: fields
-                .obligations
+                .goals
                 .into_iter()
                 .map(|goal| {
                     Obligation::new(

compiler/rustc_infer/src/infer/mod.rs

@@ -1,6 +1,9 @@
 pub use at::DefineOpaqueTypes;
 pub use freshen::TypeFreshener;
 pub use lexical_region_resolve::RegionResolutionError;
+pub use relate::combine::CombineFields;
+pub use relate::combine::PredicateEmittingRelation;
+pub use relate::StructurallyRelateAliases;
 pub use rustc_macros::{TypeFoldable, TypeVisitable};
 pub use rustc_middle::ty::IntVarValue;
 pub use BoundRegionConversionTime::*;
@@ -8,7 +11,7 @@ pub use RegionVariableOrigin::*;
 pub use SubregionOrigin::*;
 pub use ValuePairs::*;
 
-use crate::infer::relate::{CombineFields, RelateResult};
+use crate::infer::relate::RelateResult;
 use crate::traits::{self, ObligationCause, ObligationInspector, PredicateObligation, TraitEngine};
 use error_reporting::TypeErrCtxt;
 use free_regions::RegionRelations;

compiler/rustc_infer/src/infer/relate/combine.rs

@@ -39,7 +39,7 @@ pub struct CombineFields<'infcx, 'tcx> {
     pub infcx: &'infcx InferCtxt<'tcx>,
     pub trace: TypeTrace<'tcx>,
     pub param_env: ty::ParamEnv<'tcx>,
-    pub obligations: Vec<Goal<'tcx, ty::Predicate<'tcx>>>,
+    pub goals: Vec<Goal<'tcx, ty::Predicate<'tcx>>>,
     pub define_opaque_types: DefineOpaqueTypes,
 }
 
@@ -50,11 +50,11 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
         param_env: ty::ParamEnv<'tcx>,
         define_opaque_types: DefineOpaqueTypes,
     ) -> Self {
-        Self { infcx, trace, param_env, define_opaque_types, obligations: vec![] }
+        Self { infcx, trace, param_env, define_opaque_types, goals: vec![] }
     }
 
     pub(crate) fn into_obligations(self) -> Vec<PredicateObligation<'tcx>> {
-        self.obligations
+        self.goals
             .into_iter()
             .map(|goal| {
                 Obligation::new(
@@ -76,7 +76,7 @@ impl<'tcx> InferCtxt<'tcx> {
         b: Ty<'tcx>,
     ) -> RelateResult<'tcx, Ty<'tcx>>
     where
-        R: ObligationEmittingRelation<'tcx>,
+        R: PredicateEmittingRelation<'tcx>,
     {
         debug_assert!(!a.has_escaping_bound_vars());
         debug_assert!(!b.has_escaping_bound_vars());
@@ -140,7 +140,7 @@ impl<'tcx> InferCtxt<'tcx> {
                         relate::structurally_relate_tys(relation, a, b)
                     }
                     StructurallyRelateAliases::No => {
-                        relation.register_type_relate_obligation(a, b);
+                        relation.register_alias_relate_predicate(a, b);
                         Ok(a)
                     }
                 }
@@ -171,7 +171,7 @@ impl<'tcx> InferCtxt<'tcx> {
         b: ty::Const<'tcx>,
     ) -> RelateResult<'tcx, ty::Const<'tcx>>
     where
-        R: ObligationEmittingRelation<'tcx>,
+        R: PredicateEmittingRelation<'tcx>,
     {
         debug!("{}.consts({:?}, {:?})", relation.tag(), a, b);
         debug_assert!(!a.has_escaping_bound_vars());
@@ -309,14 +309,14 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
         &mut self,
         obligations: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
     ) {
-        self.obligations.extend(obligations);
+        self.goals.extend(obligations);
     }
 
     pub fn register_predicates(
         &mut self,
         obligations: impl IntoIterator<Item: Upcast<TyCtxt<'tcx>, ty::Predicate<'tcx>>>,
     ) {
-        self.obligations.extend(
+        self.goals.extend(
             obligations
                 .into_iter()
                 .map(|to_pred| Goal::new(self.infcx.tcx, self.param_env, to_pred)),
@@ -324,7 +324,7 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
     }
 }
 
-pub trait ObligationEmittingRelation<'tcx>: TypeRelation<TyCtxt<'tcx>> {
+pub trait PredicateEmittingRelation<'tcx>: TypeRelation<TyCtxt<'tcx>> {
     fn span(&self) -> Span;
 
     fn param_env(&self) -> ty::ParamEnv<'tcx>;
@@ -335,19 +335,18 @@ pub trait ObligationEmittingRelation<'tcx>: TypeRelation<TyCtxt<'tcx>> {
     fn structurally_relate_aliases(&self) -> StructurallyRelateAliases;
 
     /// Register obligations that must hold in order for this relation to hold
-    fn register_obligations(
+    fn register_goals(
         &mut self,
         obligations: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
     );
 
-    /// Register predicates that must hold in order for this relation to hold. Uses
+    /// Register predicates that must hold in order for this relation to hold.
-    /// a default obligation cause, [`ObligationEmittingRelation::register_obligations`] should
+    /// This uses the default `param_env` of the obligation.
-    /// be used if control over the obligation causes is required.
     fn register_predicates(
         &mut self,
         obligations: impl IntoIterator<Item: Upcast<TyCtxt<'tcx>, ty::Predicate<'tcx>>>,
     );
 
     /// 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 register_alias_relate_predicate(&mut self, a: Ty<'tcx>, b: Ty<'tcx>);
 }

compiler/rustc_infer/src/infer/relate/generalize.rs

@@ -1,7 +1,7 @@
 use std::mem;
 
 use super::StructurallyRelateAliases;
-use super::{ObligationEmittingRelation, Relate, RelateResult, TypeRelation};
+use super::{PredicateEmittingRelation, Relate, RelateResult, TypeRelation};
 use crate::infer::relate;
 use crate::infer::type_variable::TypeVariableValue;
 use crate::infer::{InferCtxt, RegionVariableOrigin};
@@ -30,7 +30,7 @@ impl<'tcx> InferCtxt<'tcx> {
     /// `TypeRelation`. Do not use this, and instead please use `At::eq`, for all
     /// other usecases (i.e. setting the value of a type var).
     #[instrument(level = "debug", skip(self, relation))]
-    pub fn instantiate_ty_var<R: ObligationEmittingRelation<'tcx>>(
+    pub fn instantiate_ty_var<R: PredicateEmittingRelation<'tcx>>(
         &self,
         relation: &mut R,
         target_is_expected: bool,
@@ -178,7 +178,7 @@ impl<'tcx> InferCtxt<'tcx> {
     ///
     /// See `tests/ui/const-generics/occurs-check/` for more examples where this is relevant.
     #[instrument(level = "debug", skip(self, relation))]
-    pub(super) fn instantiate_const_var<R: ObligationEmittingRelation<'tcx>>(
+    pub(super) fn instantiate_const_var<R: PredicateEmittingRelation<'tcx>>(
         &self,
         relation: &mut R,
         target_is_expected: bool,

compiler/rustc_infer/src/infer/relate/glb.rs

@@ -5,7 +5,7 @@ use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::Span;
 
-use super::combine::{CombineFields, ObligationEmittingRelation};
+use super::combine::{CombineFields, PredicateEmittingRelation};
 use super::lattice::{self, LatticeDir};
 use super::StructurallyRelateAliases;
 use crate::infer::{DefineOpaqueTypes, InferCtxt, SubregionOrigin};
@@ -128,7 +128,7 @@ impl<'combine, 'infcx, 'tcx> LatticeDir<'infcx, 'tcx> for Glb<'combine, 'infcx,
     }
 }
 
-impl<'tcx> ObligationEmittingRelation<'tcx> for Glb<'_, '_, 'tcx> {
+impl<'tcx> PredicateEmittingRelation<'tcx> for Glb<'_, '_, 'tcx> {
     fn span(&self) -> Span {
         self.fields.trace.span()
     }
@@ -148,14 +148,14 @@ impl<'tcx> ObligationEmittingRelation<'tcx> for Glb<'_, '_, 'tcx> {
         self.fields.register_predicates(obligations);
     }
 
-    fn register_obligations(
+    fn register_goals(
         &mut self,
         obligations: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
     ) {
         self.fields.register_obligations(obligations);
     }
 
-    fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
+    fn register_alias_relate_predicate(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
         self.register_predicates([ty::Binder::dummy(ty::PredicateKind::AliasRelate(
             a.into(),
             b.into(),

compiler/rustc_infer/src/infer/relate/lattice.rs

@@ -17,7 +17,7 @@
 //!
 //! [lattices]: https://en.wikipedia.org/wiki/Lattice_(order)
 
-use super::combine::ObligationEmittingRelation;
+use super::combine::PredicateEmittingRelation;
 use crate::infer::{DefineOpaqueTypes, InferCtxt};
 use crate::traits::ObligationCause;
 
@@ -31,7 +31,7 @@ use rustc_middle::ty::{self, Ty};
 ///
 /// GLB moves "down" the lattice (to smaller values); LUB moves
 /// "up" the lattice (to bigger values).
-pub trait LatticeDir<'f, 'tcx>: ObligationEmittingRelation<'tcx> {
+pub trait LatticeDir<'f, 'tcx>: PredicateEmittingRelation<'tcx> {
     fn infcx(&self) -> &'f InferCtxt<'tcx>;
 
     fn cause(&self) -> &ObligationCause<'tcx>;
@@ -109,7 +109,7 @@ where
                 && def_id.is_local()
                 && !this.infcx().next_trait_solver() =>
         {
-            this.register_obligations(
+            this.register_goals(
                 infcx
                     .handle_opaque_type(a, b, this.cause(), this.param_env())?
                     .obligations

compiler/rustc_infer/src/infer/relate/lub.rs

@@ -1,6 +1,6 @@
 //! Least upper bound. See [`lattice`].
 
-use super::combine::{CombineFields, ObligationEmittingRelation};
+use super::combine::{CombineFields, PredicateEmittingRelation};
 use super::lattice::{self, LatticeDir};
 use super::StructurallyRelateAliases;
 use crate::infer::{DefineOpaqueTypes, InferCtxt, SubregionOrigin};
@@ -128,7 +128,7 @@ impl<'combine, 'infcx, 'tcx> LatticeDir<'infcx, 'tcx> for Lub<'combine, 'infcx,
     }
 }
 
-impl<'tcx> ObligationEmittingRelation<'tcx> for Lub<'_, '_, 'tcx> {
+impl<'tcx> PredicateEmittingRelation<'tcx> for Lub<'_, '_, 'tcx> {
     fn span(&self) -> Span {
         self.fields.trace.span()
     }
@@ -148,14 +148,14 @@ impl<'tcx> ObligationEmittingRelation<'tcx> for Lub<'_, '_, 'tcx> {
         self.fields.register_predicates(obligations);
     }
 
-    fn register_obligations(
+    fn register_goals(
         &mut self,
         obligations: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
     ) {
         self.fields.register_obligations(obligations)
     }
 
-    fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
+    fn register_alias_relate_predicate(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
         self.register_predicates([ty::Binder::dummy(ty::PredicateKind::AliasRelate(
             a.into(),
             b.into(),

compiler/rustc_infer/src/infer/relate/mod.rs

@@ -6,7 +6,7 @@ pub use rustc_middle::ty::relate::*;
 
 pub use self::_match::MatchAgainstFreshVars;
 pub use self::combine::CombineFields;
-pub use self::combine::ObligationEmittingRelation;
+pub use self::combine::PredicateEmittingRelation;
 
 pub mod _match;
 pub(super) mod combine;

compiler/rustc_infer/src/infer/relate/type_relating.rs

@@ -1,5 +1,5 @@
 use super::combine::CombineFields;
-use crate::infer::relate::{ObligationEmittingRelation, StructurallyRelateAliases};
+use crate::infer::relate::{PredicateEmittingRelation, StructurallyRelateAliases};
 use crate::infer::BoundRegionConversionTime::HigherRankedType;
 use crate::infer::{DefineOpaqueTypes, SubregionOrigin};
 use rustc_middle::traits::solve::Goal;
@@ -87,7 +87,7 @@ impl<'tcx> TypeRelation<TyCtxt<'tcx>> for TypeRelating<'_, '_, 'tcx> {
                     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(Goal::new(
+                        self.fields.goals.push(Goal::new(
                             self.tcx(),
                             self.fields.param_env,
                             ty::Binder::dummy(ty::PredicateKind::Subtype(ty::SubtypePredicate {
@@ -100,7 +100,7 @@ impl<'tcx> TypeRelation<TyCtxt<'tcx>> for TypeRelating<'_, '_, 'tcx> {
                     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(Goal::new(
+                        self.fields.goals.push(Goal::new(
                             self.tcx(),
                             self.fields.param_env,
                             ty::Binder::dummy(ty::PredicateKind::Subtype(ty::SubtypePredicate {
@@ -151,7 +151,7 @@ impl<'tcx> TypeRelation<TyCtxt<'tcx>> for TypeRelating<'_, '_, 'tcx> {
                     && !infcx.next_trait_solver() =>
             {
                 // FIXME: Don't shuttle between Goal and Obligation
-                self.fields.obligations.extend(
+                self.fields.goals.extend(
                     infcx
                         .handle_opaque_type(a, b, &self.fields.trace.cause, self.param_env())?
                         .obligations
@@ -298,7 +298,7 @@ impl<'tcx> TypeRelation<TyCtxt<'tcx>> for TypeRelating<'_, '_, 'tcx> {
     }
 }
 
-impl<'tcx> ObligationEmittingRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
+impl<'tcx> PredicateEmittingRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
     fn span(&self) -> Span {
         self.fields.trace.span()
     }
@@ -318,14 +318,14 @@ impl<'tcx> ObligationEmittingRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
         self.fields.register_predicates(obligations);
     }
 
-    fn register_obligations(
+    fn register_goals(
         &mut self,
         obligations: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
     ) {
         self.fields.register_obligations(obligations);
     }
 
-    fn register_type_relate_obligation(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) {
+    fn register_alias_relate_predicate(&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(),