Auto merge of #131263 - compiler-errors:solver-relating, r=lcnr

Introduce SolverRelating type relation to the new solver

Redux of #128744.

Splits out relate for the new solver so that implementors don't need to implement it themselves.

r? lcnr

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -11,6 +11,7 @@ use rustc_middle::span_bug;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::fold::FnMutDelegate;
+use rustc_middle::ty::relate::combine::{super_combine_consts, super_combine_tys};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::symbol::sym;
 use rustc_span::{Span, Symbol};
@@ -362,7 +363,7 @@ impl<'b, 'tcx> TypeRelation<TyCtxt<'tcx>> for NllTypeRelating<'_, 'b, 'tcx> {
                 &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.next_trait_solver() => {
-                infcx.super_combine_tys(self, a, b).map(|_| ()).or_else(|err| {
+                super_combine_tys(&infcx.infcx, self, a, b).map(|_| ()).or_else(|err| {
                     // This behavior is only there for the old solver, the new solver
                     // shouldn't ever fail. Instead, it unconditionally emits an
                     // alias-relate goal.
@@ -385,7 +386,7 @@ impl<'b, 'tcx> TypeRelation<TyCtxt<'tcx>> for NllTypeRelating<'_, 'b, 'tcx> {
                 debug!(?a, ?b, ?self.ambient_variance);
 
                 // Will also handle unification of `IntVar` and `FloatVar`.
-                self.type_checker.infcx.super_combine_tys(self, a, b)?;
+                super_combine_tys(&self.type_checker.infcx.infcx, self, a, b)?;
             }
         }
 
@@ -422,7 +423,7 @@ impl<'b, 'tcx> TypeRelation<TyCtxt<'tcx>> for NllTypeRelating<'_, 'b, 'tcx> {
         assert!(!a.has_non_region_infer(), "unexpected inference var {:?}", a);
         assert!(!b.has_non_region_infer(), "unexpected inference var {:?}", b);
 
-        self.type_checker.infcx.super_combine_consts(self, a, b)
+        super_combine_consts(&self.type_checker.infcx.infcx, self, a, b)
     }
 
     #[instrument(skip(self), level = "trace")]

compiler/rustc_infer/src/infer/at.rs

@@ -27,11 +27,14 @@
 
 use relate::lattice::{LatticeOp, LatticeOpKind};
 use rustc_middle::bug;
+use rustc_middle::ty::relate::solver_relating::RelateExt as NextSolverRelate;
 use rustc_middle::ty::{Const, ImplSubject};
 
 use super::*;
 use crate::infer::relate::type_relating::TypeRelating;
-use crate::infer::relate::{Relate, StructurallyRelateAliases, TypeRelation};
+use crate::infer::relate::{Relate, TypeRelation};
+use crate::traits::Obligation;
+use crate::traits::solve::Goal;
 
 /// Whether we should define opaque types or just treat them opaquely.
 ///
@@ -109,16 +112,26 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     where
         T: ToTrace<'tcx>,
     {
-        let mut op = TypeRelating::new(
-            self.infcx,
-            ToTrace::to_trace(self.cause, expected, actual),
-            self.param_env,
-            define_opaque_types,
-            StructurallyRelateAliases::No,
-            ty::Contravariant,
-        );
-        op.relate(expected, actual)?;
-        Ok(InferOk { value: (), obligations: op.into_obligations() })
+        if self.infcx.next_trait_solver {
+            NextSolverRelate::relate(
+                self.infcx,
+                self.param_env,
+                expected,
+                ty::Contravariant,
+                actual,
+            )
+            .map(|goals| self.goals_to_obligations(goals))
+        } else {
+            let mut op = TypeRelating::new(
+                self.infcx,
+                ToTrace::to_trace(self.cause, expected, actual),
+                self.param_env,
+                define_opaque_types,
+                ty::Contravariant,
+            );
+            op.relate(expected, actual)?;
+            Ok(InferOk { value: (), obligations: op.into_obligations() })
+        }
     }
 
     /// Makes `expected <: actual`.
@@ -131,16 +144,20 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     where
         T: ToTrace<'tcx>,
     {
-        let mut op = TypeRelating::new(
-            self.infcx,
-            ToTrace::to_trace(self.cause, expected, actual),
-            self.param_env,
-            define_opaque_types,
-            StructurallyRelateAliases::No,
-            ty::Covariant,
-        );
-        op.relate(expected, actual)?;
-        Ok(InferOk { value: (), obligations: op.into_obligations() })
+        if self.infcx.next_trait_solver {
+            NextSolverRelate::relate(self.infcx, self.param_env, expected, ty::Covariant, actual)
+                .map(|goals| self.goals_to_obligations(goals))
+        } else {
+            let mut op = TypeRelating::new(
+                self.infcx,
+                ToTrace::to_trace(self.cause, expected, actual),
+                self.param_env,
+                define_opaque_types,
+                ty::Covariant,
+            );
+            op.relate(expected, actual)?;
+            Ok(InferOk { value: (), obligations: op.into_obligations() })
+        }
     }
 
     /// Makes `expected == actual`.
@@ -172,16 +189,20 @@ impl<'a, 'tcx> At<'a, 'tcx> {
     where
         T: Relate<TyCtxt<'tcx>>,
     {
-        let mut op = TypeRelating::new(
-            self.infcx,
-            trace,
-            self.param_env,
-            define_opaque_types,
-            StructurallyRelateAliases::No,
-            ty::Invariant,
-        );
-        op.relate(expected, actual)?;
-        Ok(InferOk { value: (), obligations: op.into_obligations() })
+        if self.infcx.next_trait_solver {
+            NextSolverRelate::relate(self.infcx, self.param_env, expected, ty::Invariant, actual)
+                .map(|goals| self.goals_to_obligations(goals))
+        } else {
+            let mut op = TypeRelating::new(
+                self.infcx,
+                trace,
+                self.param_env,
+                define_opaque_types,
+                ty::Invariant,
+            );
+            op.relate(expected, actual)?;
+            Ok(InferOk { value: (), obligations: op.into_obligations() })
+        }
     }
 
     pub fn relate<T>(
@@ -208,49 +229,6 @@ impl<'a, 'tcx> At<'a, 'tcx> {
         }
     }
 
-    /// Used in the new solver since we don't care about tracking an `ObligationCause`.
-    pub fn relate_no_trace<T>(
-        self,
-        expected: T,
-        variance: ty::Variance,
-        actual: T,
-    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution>
-    where
-        T: Relate<TyCtxt<'tcx>>,
-    {
-        let mut op = TypeRelating::new(
-            self.infcx,
-            TypeTrace::dummy(self.cause),
-            self.param_env,
-            DefineOpaqueTypes::Yes,
-            StructurallyRelateAliases::No,
-            variance,
-        );
-        op.relate(expected, actual)?;
-        Ok(op.into_obligations().into_iter().map(|o| o.into()).collect())
-    }
-
-    /// Used in the new solver since we don't care about tracking an `ObligationCause`.
-    pub fn eq_structurally_relating_aliases_no_trace<T>(
-        self,
-        expected: T,
-        actual: T,
-    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution>
-    where
-        T: Relate<TyCtxt<'tcx>>,
-    {
-        let mut op = TypeRelating::new(
-            self.infcx,
-            TypeTrace::dummy(self.cause),
-            self.param_env,
-            DefineOpaqueTypes::Yes,
-            StructurallyRelateAliases::Yes,
-            ty::Invariant,
-        );
-        op.relate(expected, actual)?;
-        Ok(op.into_obligations().into_iter().map(|o| o.into()).collect())
-    }
-
     /// Computes the least-upper-bound, or mutual supertype, of two
     /// values. The order of the arguments doesn't matter, but since
     /// this can result in an error (e.g., if asked to compute LUB of
@@ -269,6 +247,26 @@ impl<'a, 'tcx> At<'a, 'tcx> {
         let value = op.relate(expected, actual)?;
         Ok(InferOk { value, obligations: op.into_obligations() })
     }
+
+    fn goals_to_obligations(
+        &self,
+        goals: Vec<Goal<'tcx, ty::Predicate<'tcx>>>,
+    ) -> InferOk<'tcx, ()> {
+        InferOk {
+            value: (),
+            obligations: goals
+                .into_iter()
+                .map(|goal| {
+                    Obligation::new(
+                        self.infcx.tcx,
+                        self.cause.clone(),
+                        goal.param_env,
+                        goal.predicate,
+                    )
+                })
+                .collect(),
+        }
+    }
 }
 
 impl<'tcx> ToTrace<'tcx> for ImplSubject<'tcx> {

compiler/rustc_infer/src/infer/context.rs

@@ -1,22 +1,27 @@
 ///! Definition of `InferCtxtLike` from the librarified type layer.
 use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_middle::infer::unify_key::EffectVarValue;
 use rustc_middle::traits::ObligationCause;
-use rustc_middle::traits::solve::{Goal, NoSolution, SolverMode};
+use rustc_middle::traits::solve::SolverMode;
 use rustc_middle::ty::fold::TypeFoldable;
+use rustc_middle::ty::relate::RelateResult;
+use rustc_middle::ty::relate::combine::PredicateEmittingRelation;
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_span::DUMMY_SP;
-use rustc_type_ir::InferCtxtLike;
-use rustc_type_ir::relate::Relate;
+use rustc_span::{DUMMY_SP, ErrorGuaranteed};
 
 use super::{BoundRegionConversionTime, InferCtxt, SubregionOrigin};
 
-impl<'tcx> InferCtxtLike for InferCtxt<'tcx> {
+impl<'tcx> rustc_type_ir::InferCtxtLike for InferCtxt<'tcx> {
     type Interner = TyCtxt<'tcx>;
 
     fn cx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }
 
+    fn next_trait_solver(&self) -> bool {
+        self.next_trait_solver
+    }
+
     fn solver_mode(&self) -> ty::solve::SolverMode {
         match self.intercrate {
             true => SolverMode::Coherence,
@@ -131,29 +136,86 @@ impl<'tcx> InferCtxtLike for InferCtxt<'tcx> {
         self.enter_forall(value, f)
     }
 
-    fn relate<T: Relate<TyCtxt<'tcx>>>(
+    fn equate_ty_vids_raw(&self, a: rustc_type_ir::TyVid, b: rustc_type_ir::TyVid) {
+        self.inner.borrow_mut().type_variables().equate(a, b);
+    }
+
+    fn equate_int_vids_raw(&self, a: rustc_type_ir::IntVid, b: rustc_type_ir::IntVid) {
+        self.inner.borrow_mut().int_unification_table().union(a, b);
+    }
+
+    fn equate_float_vids_raw(&self, a: rustc_type_ir::FloatVid, b: rustc_type_ir::FloatVid) {
+        self.inner.borrow_mut().float_unification_table().union(a, b);
+    }
+
+    fn equate_const_vids_raw(&self, a: rustc_type_ir::ConstVid, b: rustc_type_ir::ConstVid) {
+        self.inner.borrow_mut().const_unification_table().union(a, b);
+    }
+
+    fn equate_effect_vids_raw(&self, a: rustc_type_ir::EffectVid, b: rustc_type_ir::EffectVid) {
+        self.inner.borrow_mut().effect_unification_table().union(a, b);
+    }
+
+    fn instantiate_ty_var_raw<R: PredicateEmittingRelation<Self>>(
         &self,
-        param_env: ty::ParamEnv<'tcx>,
-        lhs: T,
-        variance: ty::Variance,
-        rhs: T,
-    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution> {
-        self.at(&ObligationCause::dummy(), param_env).relate_no_trace(lhs, variance, rhs)
+        relation: &mut R,
+        target_is_expected: bool,
+        target_vid: rustc_type_ir::TyVid,
+        instantiation_variance: rustc_type_ir::Variance,
+        source_ty: Ty<'tcx>,
+    ) -> RelateResult<'tcx, ()> {
+        self.instantiate_ty_var(
+            relation,
+            target_is_expected,
+            target_vid,
+            instantiation_variance,
+            source_ty,
+        )
+    }
+
+    fn instantiate_int_var_raw(
+        &self,
+        vid: rustc_type_ir::IntVid,
+        value: rustc_type_ir::IntVarValue,
+    ) {
+        self.inner.borrow_mut().int_unification_table().union_value(vid, value);
+    }
+
+    fn instantiate_float_var_raw(
+        &self,
+        vid: rustc_type_ir::FloatVid,
+        value: rustc_type_ir::FloatVarValue,
+    ) {
+        self.inner.borrow_mut().float_unification_table().union_value(vid, value);
+    }
+
+    fn instantiate_effect_var_raw(&self, vid: rustc_type_ir::EffectVid, value: ty::Const<'tcx>) {
+        self.inner
+            .borrow_mut()
+            .effect_unification_table()
+            .union_value(vid, EffectVarValue::Known(value));
     }
 
-    fn eq_structurally_relating_aliases<T: Relate<TyCtxt<'tcx>>>(
+    fn instantiate_const_var_raw<R: PredicateEmittingRelation<Self>>(
         &self,
-        param_env: ty::ParamEnv<'tcx>,
-        lhs: T,
-        rhs: T,
-    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution> {
-        self.at(&ObligationCause::dummy(), param_env)
-            .eq_structurally_relating_aliases_no_trace(lhs, rhs)
+        relation: &mut R,
+        target_is_expected: bool,
+        target_vid: rustc_type_ir::ConstVid,
+        source_ct: ty::Const<'tcx>,
+    ) -> RelateResult<'tcx, ()> {
+        self.instantiate_const_var(relation, target_is_expected, target_vid, source_ct)
+    }
+
+    fn set_tainted_by_errors(&self, e: ErrorGuaranteed) {
+        self.set_tainted_by_errors(e)
     }
 
     fn shallow_resolve(&self, ty: Ty<'tcx>) -> Ty<'tcx> {
         self.shallow_resolve(ty)
     }
+    fn shallow_resolve_const(&self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
+        self.shallow_resolve_const(ct)
+    }
 
     fn resolve_vars_if_possible<T>(&self, value: T) -> T
     where
@@ -167,7 +229,19 @@ impl<'tcx> InferCtxtLike for InferCtxt<'tcx> {
     }
 
     fn sub_regions(&self, sub: ty::Region<'tcx>, sup: ty::Region<'tcx>) {
-        self.sub_regions(SubregionOrigin::RelateRegionParamBound(DUMMY_SP, None), sub, sup)
+        self.inner.borrow_mut().unwrap_region_constraints().make_subregion(
+            SubregionOrigin::RelateRegionParamBound(DUMMY_SP, None),
+            sub,
+            sup,
+        );
+    }
+
+    fn equate_regions(&self, a: ty::Region<'tcx>, b: ty::Region<'tcx>) {
+        self.inner.borrow_mut().unwrap_region_constraints().make_eqregion(
+            SubregionOrigin::RelateRegionParamBound(DUMMY_SP, None),
+            a,
+            b,
+        );
     }
 
     fn register_ty_outlives(&self, ty: Ty<'tcx>, r: ty::Region<'tcx>) {