Pull opaque type handling out of the type relating delegate

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -1,6 +1,6 @@
 use rustc_infer::infer::nll_relate::{NormalizationStrategy, TypeRelating, TypeRelatingDelegate};
 use rustc_infer::infer::NllRegionVariableOrigin;
-use rustc_infer::traits::ObligationCause;
+use rustc_infer::traits::PredicateObligations;
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::relate::TypeRelation;
@@ -155,27 +155,16 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
         true
     }
 
-    fn register_opaque_type(
+    fn register_opaque_type_obligations(
         &mut self,
-        a: Ty<'tcx>,
+        obligations: PredicateObligations<'tcx>,
-        b: Ty<'tcx>,
-        a_is_expected: bool,
     ) -> Result<(), TypeError<'tcx>> {
-        let param_env = self.param_env();
-        let span = self.span();
-        let def_id = self.type_checker.body.source.def_id().expect_local();
-        let body_id = self.type_checker.tcx().hir().local_def_id_to_hir_id(def_id);
-        let cause = ObligationCause::misc(span, body_id);
         self.type_checker
             .fully_perform_op(
                 self.locations,
                 self.category,
                 InstantiateOpaqueType {
-                    obligations: self
+                    obligations,
-                        .type_checker
-                        .infcx
-                        .handle_opaque_type(a, b, a_is_expected, &cause, param_env)?
-                        .obligations,
                     // These fields are filled in during execution of the operation
                     base_universe: None,
                     region_constraints: None,

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -16,8 +16,8 @@ use crate::infer::nll_relate::{NormalizationStrategy, TypeRelating, TypeRelating
 use crate::infer::region_constraints::{Constraint, RegionConstraintData};
 use crate::infer::{InferCtxt, InferOk, InferResult, NllRegionVariableOrigin};
 use crate::traits::query::{Fallible, NoSolution};
-use crate::traits::TraitEngine;
 use crate::traits::{Obligation, ObligationCause, PredicateObligation};
+use crate::traits::{PredicateObligations, TraitEngine};
 use rustc_data_structures::captures::Captures;
 use rustc_index::vec::Idx;
 use rustc_index::vec::IndexVec;
@@ -509,7 +509,7 @@ impl<'tcx> InferCtxt<'tcx> {
         for &(a, b) in &query_response.value.opaque_types {
             let a = substitute_value(self.tcx, &result_subst, a);
             let b = substitute_value(self.tcx, &result_subst, b);
-            obligations.extend(self.handle_opaque_type(a, b, true, cause, param_env)?.obligations);
+            obligations.extend(self.at(cause, param_env).eq(a, b)?.obligations);
         }
 
         Ok(InferOk { value: result_subst, obligations })
@@ -741,17 +741,11 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
         true
     }
 
-    fn register_opaque_type(
+    fn register_opaque_type_obligations(
         &mut self,
-        a: Ty<'tcx>,
+        obligations: PredicateObligations<'tcx>,
-        b: Ty<'tcx>,
-        a_is_expected: bool,
     ) -> Result<(), TypeError<'tcx>> {
-        self.obligations.extend(
+        self.obligations.extend(obligations);
-            self.infcx
-                .handle_opaque_type(a, b, a_is_expected, &self.cause, self.param_env)?
-                .obligations,
-        );
         Ok(())
     }
 }

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

@@ -25,7 +25,9 @@ use crate::infer::combine::ConstEquateRelation;
 use crate::infer::InferCtxt;
 use crate::infer::{ConstVarValue, ConstVariableValue};
 use crate::infer::{TypeVariableOrigin, TypeVariableOriginKind};
+use crate::traits::PredicateObligation;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
 use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
@@ -91,11 +93,9 @@ pub trait TypeRelatingDelegate<'tcx> {
     );
 
     fn const_equate(&mut self, a: ty::Const<'tcx>, b: ty::Const<'tcx>);
-    fn register_opaque_type(
+    fn register_opaque_type_obligations(
         &mut self,
-        a: Ty<'tcx>,
+        obligations: Vec<PredicateObligation<'tcx>>,
-        b: Ty<'tcx>,
-        a_is_expected: bool,
     ) -> Result<(), TypeError<'tcx>>;
 
     /// Creates a new universe index. Used when instantiating placeholders.
@@ -414,7 +414,12 @@ where
             (_, &ty::Opaque(..)) => (generalize(a, true)?, b),
             _ => unreachable!(),
         };
-        self.delegate.register_opaque_type(a, b, true)?;
+        let cause = ObligationCause::dummy_with_span(self.delegate.span());
+        let obligations = self
+            .infcx
+            .handle_opaque_type(a, b, true, &cause, self.delegate.param_env())?
+            .obligations;
+        self.delegate.register_opaque_type_obligations(obligations)?;
         trace!(a = ?a.kind(), b = ?b.kind(), "opaque type instantiated");
         Ok(a)
     }