Make QueryOutlivesConstraint contain a ConstraintCategory

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -2295,7 +2295,13 @@ impl<'tcx> ClosureRegionRequirementsExt<'tcx> for ClosureRegionRequirements<'tcx
                              outlives_requirement={:?}",
                             region, outlived_region, outlives_requirement,
                         );
-                        ty::Binder::dummy(ty::OutlivesPredicate(region.into(), outlived_region))
+                        (
+                            ty::Binder::dummy(ty::OutlivesPredicate(
+                                region.into(),
+                                outlived_region,
+                            )),
+                            ConstraintCategory::BoringNoLocation,
+                        )
                     }
 
                     ClosureOutlivesSubject::Ty(ty) => {
@@ -2305,7 +2311,10 @@ impl<'tcx> ClosureRegionRequirementsExt<'tcx> for ClosureRegionRequirements<'tcx
                              outlives_requirement={:?}",
                             ty, outlived_region, outlives_requirement,
                         );
-                        ty::Binder::dummy(ty::OutlivesPredicate(ty.into(), outlived_region))
+                        (
+                            ty::Binder::dummy(ty::OutlivesPredicate(ty.into(), outlived_region)),
+                            ConstraintCategory::BoringNoLocation,
+                        )
                     }
                 }
             })

compiler/rustc_borrowck/src/type_check/constraint_conversion.rs

@@ -98,9 +98,12 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         // region constraints like `for<'a> 'a: 'b`. At some point
         // when we move to universes, we will, and this assertion
         // will start to fail.
-        let ty::OutlivesPredicate(k1, r2) = query_constraint.no_bound_vars().unwrap_or_else(|| {
-            bug!("query_constraint {:?} contained bound vars", query_constraint,);
-        });
+        let ty::OutlivesPredicate(k1, r2) =
+            query_constraint.0.no_bound_vars().unwrap_or_else(|| {
+                bug!("query_constraint {:?} contained bound vars", query_constraint,);
+            });
+
+        let _constraint_category = query_constraint.1;
 
         match k1.unpack() {
             GenericArgKind::Lifetime(r1) => {

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -2591,7 +2591,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 .enumerate()
                 .filter_map(|(idx, constraint)| {
                     let ty::OutlivesPredicate(k1, r2) =
-                        constraint.no_bound_vars().unwrap_or_else(|| {
+                        constraint.0.no_bound_vars().unwrap_or_else(|| {
                             bug!("query_constraint {:?} contained bound vars", constraint,);
                         });
 

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

@@ -22,6 +22,7 @@ use rustc_data_structures::captures::Captures;
 use rustc_index::vec::Idx;
 use rustc_index::vec::IndexVec;
 use rustc_middle::arena::ArenaAllocatable;
+use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::relate::TypeRelation;
@@ -248,6 +249,8 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         // the original values `v_o` that was canonicalized into a
         // variable...
 
+        let constraint_category = ConstraintCategory::BoringNoLocation;
+
         for (index, original_value) in original_values.var_values.iter().enumerate() {
             // ...with the value `v_r` of that variable from the query.
             let result_value = query_response.substitute_projected(self.tcx, &result_subst, |v| {
@@ -263,12 +266,14 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
                 (GenericArgKind::Lifetime(v_o), GenericArgKind::Lifetime(v_r)) => {
                     // To make `v_o = v_r`, we emit `v_o: v_r` and `v_r: v_o`.
                     if v_o != v_r {
-                        output_query_region_constraints
-                            .outlives
-                            .push(ty::Binder::dummy(ty::OutlivesPredicate(v_o.into(), v_r)));
-                        output_query_region_constraints
-                            .outlives
-                            .push(ty::Binder::dummy(ty::OutlivesPredicate(v_r.into(), v_o)));
+                        output_query_region_constraints.outlives.push((
+                            ty::Binder::dummy(ty::OutlivesPredicate(v_o.into(), v_r)),
+                            constraint_category,
+                        ));
+                        output_query_region_constraints.outlives.push((
+                            ty::Binder::dummy(ty::OutlivesPredicate(v_r.into(), v_o)),
+                            constraint_category,
+                        ));
                     }
                 }
 
@@ -314,7 +319,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
                 // Screen out `'a: 'a` cases -- we skip the binder here but
                 // only compare the inner values to one another, so they are still at
                 // consistent binding levels.
-                let ty::OutlivesPredicate(k1, r2) = r_c.skip_binder();
+                let ty::OutlivesPredicate(k1, r2) = r_c.0.skip_binder();
                 if k1 != r2.into() { Some(r_c) } else { None }
             }),
         );
@@ -559,7 +564,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         cause: ObligationCause<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> Obligation<'tcx, ty::Predicate<'tcx>> {
-        let ty::OutlivesPredicate(k1, r2) = predicate.skip_binder();
+        let ty::OutlivesPredicate(k1, r2) = predicate.0.skip_binder();
 
         let atom = match k1.unpack() {
             GenericArgKind::Lifetime(r1) => {
@@ -574,7 +579,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
                 span_bug!(cause.span, "unexpected const outlives {:?}", predicate);
             }
         };
-        let predicate = predicate.rebind(atom).to_predicate(self.tcx);
+        let predicate = predicate.0.rebind(atom).to_predicate(self.tcx);
 
         Obligation::new(cause, param_env, predicate)
     }
@@ -638,26 +643,34 @@ pub fn make_query_region_constraints<'tcx>(
 
     let outlives: Vec<_> = constraints
         .iter()
-        .map(|(k, _)| match *k {
-            // Swap regions because we are going from sub (<=) to outlives
-            // (>=).
-            Constraint::VarSubVar(v1, v2) => ty::OutlivesPredicate(
-                tcx.mk_region(ty::ReVar(v2)).into(),
-                tcx.mk_region(ty::ReVar(v1)),
-            ),
-            Constraint::VarSubReg(v1, r2) => {
-                ty::OutlivesPredicate(r2.into(), tcx.mk_region(ty::ReVar(v1)))
-            }
-            Constraint::RegSubVar(r1, v2) => {
-                ty::OutlivesPredicate(tcx.mk_region(ty::ReVar(v2)).into(), r1)
-            }
-            Constraint::RegSubReg(r1, r2) => ty::OutlivesPredicate(r2.into(), r1),
+        .map(|(k, _)| {
+            let constraint = ty::Binder::dummy(match *k {
+                // Swap regions because we are going from sub (<=) to outlives
+                // (>=).
+                Constraint::VarSubVar(v1, v2) => ty::OutlivesPredicate(
+                    tcx.mk_region(ty::ReVar(v2)).into(),
+                    tcx.mk_region(ty::ReVar(v1)),
+                ),
+                Constraint::VarSubReg(v1, r2) => {
+                    ty::OutlivesPredicate(r2.into(), tcx.mk_region(ty::ReVar(v1)))
+                }
+                Constraint::RegSubVar(r1, v2) => {
+                    ty::OutlivesPredicate(tcx.mk_region(ty::ReVar(v2)).into(), r1)
+                }
+                Constraint::RegSubReg(r1, r2) => ty::OutlivesPredicate(r2.into(), r1),
+            });
+
+            (constraint, ConstraintCategory::BoringNoLocation)
         })
-        .map(ty::Binder::dummy) // no bound vars in the code above
         .chain(
             outlives_obligations
-                .map(|(ty, r)| ty::OutlivesPredicate(ty.into(), r))
-                .map(ty::Binder::dummy), // no bound vars in the code above
+                // no bound vars in the code above
+                .map(|(ty, r)| {
+                    (
+                        ty::Binder::dummy(ty::OutlivesPredicate(ty.into(), r)),
+                        ConstraintCategory::BoringNoLocation,
+                    )
+                }),
         )
         .collect();
 

compiler/rustc_middle/src/infer/canonical.rs

@@ -22,6 +22,7 @@
 //! [c]: https://rust-lang.github.io/chalk/book/canonical_queries/canonicalization.html
 
 use crate::infer::MemberConstraint;
+use crate::mir::ConstraintCategory;
 use crate::ty::subst::GenericArg;
 use crate::ty::{self, BoundVar, List, Region, Ty, TyCtxt};
 use rustc_index::vec::IndexVec;
@@ -301,8 +302,10 @@ impl<'tcx, V> Canonical<'tcx, V> {
     }
 }
 
-pub type QueryOutlivesConstraint<'tcx> =
-    ty::Binder<'tcx, ty::OutlivesPredicate<GenericArg<'tcx>, Region<'tcx>>>;
+pub type QueryOutlivesConstraint<'tcx> = (
+    ty::Binder<'tcx, ty::OutlivesPredicate<GenericArg<'tcx>, Region<'tcx>>>,
+    ConstraintCategory<'tcx>,
+);
 
 TrivialTypeTraversalAndLiftImpls! {
     for <'tcx> {

compiler/rustc_middle/src/mir/query.rs

@@ -327,7 +327,7 @@ rustc_data_structures::static_assert_size!(ConstraintCategory<'_>, 16);
 ///
 /// See also `rustc_const_eval::borrow_check::constraints`.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)]
-#[derive(TyEncodable, TyDecodable, HashStable)]
+#[derive(TyEncodable, TyDecodable, HashStable, Lift, TypeVisitable, TypeFoldable)]
 pub enum ConstraintCategory<'tcx> {
     Return(ReturnConstraint),
     Yield,
@@ -369,7 +369,7 @@ pub enum ConstraintCategory<'tcx> {
 }
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)]
-#[derive(TyEncodable, TyDecodable, HashStable)]
+#[derive(TyEncodable, TyDecodable, HashStable, TypeVisitable, TypeFoldable)]
 pub enum ReturnConstraint {
     Normal,
     ClosureUpvar(Field),