diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs
index 8938ed78a94..7120d5ad934 100644
--- a/compiler/rustc_infer/src/infer/canonical/query_response.rs
+++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs
@@ -128,7 +128,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         let region_constraints = self.with_region_constraints(|region_constraints| {
             make_query_region_constraints(
                 tcx,
-                region_obligations.iter().map(|(_, r_o)| (r_o.sup_type, r_o.sub_region)),
+                region_obligations.iter().map(|r_o| (r_o.sup_type, r_o.sub_region)),
                 region_constraints,
             )
         });
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 70b9096714a..c73302c7e41 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -15,7 +15,6 @@ use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::undo_log::Rollback;
 use rustc_data_structures::unify as ut;
 use rustc_errors::{DiagnosticBuilder, ErrorGuaranteed};
-use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::infer::canonical::{Canonical, CanonicalVarValues};
 use rustc_middle::infer::unify_key::{ConstVarValue, ConstVariableValue};
@@ -147,7 +146,7 @@ pub struct InferCtxtInner<'tcx> {
     /// for each body-id in this map, which will process the
     /// obligations within. This is expected to be done 'late enough'
     /// that all type inference variables have been bound and so forth.
-    region_obligations: Vec<(hir::HirId, RegionObligation<'tcx>)>,
+    region_obligations: Vec<RegionObligation<'tcx>>,
 
     undo_log: InferCtxtUndoLogs<'tcx>,
 
@@ -171,7 +170,7 @@ impl<'tcx> InferCtxtInner<'tcx> {
     }
 
     #[inline]
-    pub fn region_obligations(&self) -> &[(hir::HirId, RegionObligation<'tcx>)] {
+    pub fn region_obligations(&self) -> &[RegionObligation<'tcx>] {
         &self.region_obligations
     }
 
diff --git a/compiler/rustc_infer/src/infer/outlives/obligations.rs b/compiler/rustc_infer/src/infer/outlives/obligations.rs
index 91d6479c5cd..b839566bec9 100644
--- a/compiler/rustc_infer/src/infer/outlives/obligations.rs
+++ b/compiler/rustc_infer/src/infer/outlives/obligations.rs
@@ -68,7 +68,6 @@ use crate::infer::{
 };
 use crate::traits::{ObligationCause, ObligationCauseCode};
 use rustc_data_structures::undo_log::UndoLogs;
-use rustc_hir as hir;
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::{self, Region, Ty, TyCtxt, TypeFoldable};
 use smallvec::smallvec;
@@ -79,16 +78,11 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     /// and later processed by regionck, when full type information is
     /// available (see `region_obligations` field for more
     /// information).
-    pub fn register_region_obligation(
-        &self,
-        body_id: hir::HirId,
-        obligation: RegionObligation<'tcx>,
-    ) {
-        debug!("register_region_obligation(body_id={:?}, obligation={:?})", body_id, obligation);
-
+    #[instrument(level = "debug", skip(self))]
+    pub fn register_region_obligation(&self, obligation: RegionObligation<'tcx>) {
         let mut inner = self.inner.borrow_mut();
         inner.undo_log.push(UndoLog::PushRegionObligation);
-        inner.region_obligations.push((body_id, obligation));
+        inner.region_obligations.push(obligation);
     }
 
     pub fn register_region_obligation_with_cause(
@@ -108,14 +102,11 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
             )
         });
 
-        self.register_region_obligation(
-            cause.body_id,
-            RegionObligation { sup_type, sub_region, origin },
-        );
+        self.register_region_obligation(RegionObligation { sup_type, sub_region, origin });
     }
 
     /// Trait queries just want to pass back type obligations "as is"
-    pub fn take_registered_region_obligations(&self) -> Vec<(hir::HirId, RegionObligation<'tcx>)> {
+    pub fn take_registered_region_obligations(&self) -> Vec<RegionObligation<'tcx>> {
         std::mem::take(&mut self.inner.borrow_mut().region_obligations)
     }
 
@@ -156,7 +147,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
 
         let my_region_obligations = self.take_registered_region_obligations();
 
-        for (_body_id, RegionObligation { sup_type, sub_region, origin }) in my_region_obligations {
+        for RegionObligation { sup_type, sub_region, origin } in my_region_obligations {
             debug!(
                 "process_registered_region_obligations: sup_type={:?} sub_region={:?} origin={:?}",
                 sup_type, sub_region, origin
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
index 605c9ace5ed..c9d46b2810d 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
@@ -95,7 +95,7 @@ pub fn scrape_region_constraints<'tcx, Op: super::TypeOp<'tcx, Output = R>, R>(
         infcx.tcx,
         region_obligations
             .iter()
-            .map(|(_, r_o)| (r_o.sup_type, r_o.sub_region))
+            .map(|r_o| (r_o.sup_type, r_o.sub_region))
             .map(|(ty, r)| (infcx.resolve_vars_if_possible(ty), r)),
         &region_constraint_data,
     );