Rollup merge of #99038 - jackh726:earlybinder-cleanup, r=lcnr

Some more `EarlyBinder` cleanups

First commit has a couple unrelated cleanups, but otherwise each commit is self-explanatory

r? rust-lang/types

1 files changed, 4 insertions, 5 deletions

diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
index 3be1783ae33..f3153a64820 100644
--- a/compiler/rustc_mir_transform/src/shim.rs
+++ b/compiler/rustc_mir_transform/src/shim.rs
@@ -537,13 +537,12 @@ fn build_call_shim<'tcx>(
     };
 
     let def_id = instance.def_id();
-    let sig = tcx.fn_sig(def_id);
-    let mut sig = tcx.erase_late_bound_regions(sig);
+    let sig = tcx.bound_fn_sig(def_id);
+    let sig = sig.map_bound(|sig| tcx.erase_late_bound_regions(sig));
 
     assert_eq!(sig_substs.is_some(), !instance.has_polymorphic_mir_body());
-    if let Some(sig_substs) = sig_substs {
-        sig = EarlyBinder(sig).subst(tcx, sig_substs);
-    }
+    let mut sig =
+        if let Some(sig_substs) = sig_substs { sig.subst(tcx, sig_substs) } else { sig.0 };
 
     if let CallKind::Indirect(fnty) = call_kind {
         // `sig` determines our local decls, and thus the callee type in the `Call` terminator. This