diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
index a637f0613d1..48b8230857a 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
@@ -788,7 +788,11 @@ fn maybe_suggest_constrain_dyn_trait_impl(
 
         let tcx = self.infcx.tcx;
 
-        let instance = if let ConstraintCategory::CallArgument(Some((fn_did, substs))) = category {
+        let instance = if let ConstraintCategory::CallArgument(Some(func_ty)) = category {
+            let (fn_did, substs) = match func_ty.kind() {
+                ty::FnDef(fn_did, substs) => (fn_did, substs),
+                _ => return,
+            };
             debug!(?fn_did, ?substs);
 
             // Only suggest this on function calls, not closures
@@ -821,13 +825,10 @@ fn maybe_suggest_constrain_dyn_trait_impl(
         let mut visitor = TraitObjectVisitor(FxHashSet::default());
         visitor.visit_ty(param.param_ty);
 
-        if let Some((ident, self_ty)) =
-            self.get_impl_ident_and_self_ty_from_trait(instance.def_id(), &visitor.0)
-        {
-            self.suggest_constrain_dyn_trait_in_impl(diag, &visitor.0, ident, self_ty)
-        } else {
-            return;
-        };
+        let Some((ident, self_ty)) =
+            self.get_impl_ident_and_self_ty_from_trait(instance.def_id(), &visitor.0) else {return};
+
+        self.suggest_constrain_dyn_trait_in_impl(diag, &visitor.0, ident, self_ty);
     }
 
     #[instrument(skip(self, err), level = "debug")]
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 2cff12e3c8b..4a2b2942008 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -1418,7 +1418,7 @@ fn check_terminator(
                 ref args,
                 ref destination,
                 from_hir_call,
-                fn_span,
+                target,
                 ..
             } => {
                 self.check_operand(func, term_location);
@@ -1427,9 +1427,8 @@ fn check_terminator(
                 }
 
                 let func_ty = func.ty(body, tcx);
-                debug!("check_terminator: call, func_ty={:?}", func_ty);
                 debug!("func_ty.kind: {:?}", func_ty.kind());
-                debug!(?fn_span);
+
                 let sig = match func_ty.kind() {
                     ty::FnDef(..) | ty::FnPtr(_) => func_ty.fn_sig(tcx),
                     _ => {
@@ -1444,7 +1443,7 @@ fn check_terminator(
                 );
                 debug!(?sig);
                 let sig = self.normalize(sig, term_location);
-                self.check_call_dest(body, term, &sig, destination, target, term_location);
+                self.check_call_dest(body, term, &sig, *destination, target, term_location);
 
                 self.prove_predicates(
                     sig.inputs_and_output
@@ -1604,24 +1603,19 @@ fn check_call_inputs(
             span_mirbug!(self, term, "call to {:?} with wrong # of args", sig);
         }
 
-        let call_arg = if let TerminatorKind::Call { func, .. } = &term.kind {
-            let func_ty = func.ty(body, self.infcx.tcx);
-            if let ty::FnDef(fn_did, substs) = func_ty.kind() {
-                Some((*fn_did, *substs))
-            } else {
-                None
-            }
+        let func_ty = if let TerminatorKind::Call { func, .. } = &term.kind {
+            Some(func.ty(body, self.infcx.tcx))
         } else {
             None
         };
-        debug!(?call_arg);
+        debug!(?func_ty);
 
         for (n, (fn_arg, op_arg)) in iter::zip(sig.inputs(), args).enumerate() {
             let op_arg_ty = op_arg.ty(body, self.tcx());
 
             let op_arg_ty = self.normalize(op_arg_ty, term_location);
             let category = if from_hir_call {
-                ConstraintCategory::CallArgument(call_arg)
+                ConstraintCategory::CallArgument(func_ty)
             } else {
                 ConstraintCategory::Boring
             };
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index 4f71e3a8234..01945b543b1 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -1,7 +1,7 @@
 //! Values computed by queries that use MIR.
 
 use crate::mir::{self, Body, Promoted};
-use crate::ty::{self, subst::SubstsRef, OpaqueHiddenType, Ty, TyCtxt};
+use crate::ty::{self, OpaqueHiddenType, Ty, TyCtxt};
 use rustc_data_structures::stable_map::FxHashMap;
 use rustc_data_structures::vec_map::VecMap;
 use rustc_errors::ErrorGuaranteed;
@@ -341,6 +341,10 @@ pub struct ClosureOutlivesRequirement<'tcx> {
     pub category: ConstraintCategory<'tcx>,
 }
 
+// Make sure this enum doesn't unintentionally grow
+#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
+rustc_data_structures::static_assert_size!(ConstraintCategory<'_>, 16);
+
 /// Outlives-constraints can be categorized to determine whether and why they
 /// are interesting (for error reporting). Order of variants indicates sort
 /// order of the category, thereby influencing diagnostic output.
@@ -360,7 +364,9 @@ pub enum ConstraintCategory<'tcx> {
     ///
     /// We try to get the category that the closure used when reporting this.
     ClosureBounds,
-    CallArgument(Option<(DefId, SubstsRef<'tcx>)>),
+
+    /// Contains the function type if available.
+    CallArgument(Option<Ty<'tcx>>),
     CopyBound,
     SizedBound,
     Assignment,
diff --git a/compiler/rustc_middle/src/ty/impls_ty.rs b/compiler/rustc_middle/src/ty/impls_ty.rs
index d6b5e9ddfbd..42e5a05d63b 100644
--- a/compiler/rustc_middle/src/ty/impls_ty.rs
+++ b/compiler/rustc_middle/src/ty/impls_ty.rs
@@ -135,8 +135,8 @@ fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHas
             ty::RePlaceholder(p) => {
                 p.hash_stable(hcx, hasher);
             }
-            ty::ReVar(reg_vid) => {
-                reg_vid.hash_stable(hcx, hasher);
+            ty::ReVar(reg) => {
+                reg.hash_stable(hcx, hasher);
             }
         }
     }