From 76b494a9dd7ba5a151882afc7c85a75c5aeb94db Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Mon, 5 Sep 2022 06:44:33 +0000
Subject: [PATCH] Normalize before erasing late-bound regions in
 equal_up_to_regions

---
 .../src/transform/validate.rs                 | 29 ++++++++++---------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/compiler/rustc_const_eval/src/transform/validate.rs b/compiler/rustc_const_eval/src/transform/validate.rs
index b7988625839..f42e8aa53d1 100644
--- a/compiler/rustc_const_eval/src/transform/validate.rs
+++ b/compiler/rustc_const_eval/src/transform/validate.rs
@@ -89,20 +89,21 @@ pub fn equal_up_to_regions<'tcx>(
 
     // Normalize lifetimes away on both sides, then compare.
     let normalize = |ty: Ty<'tcx>| {
-        let ty = ty.fold_with(&mut BottomUpFolder {
-            tcx,
-            // FIXME: We erase all late-bound lifetimes, but this is not fully correct.
-            // If you have a type like `<for<'a> fn(&'a u32) as SomeTrait>::Assoc`,
-            // this is not necessarily equivalent to `<fn(&'static u32) as SomeTrait>::Assoc`,
-            // since one may have an `impl SomeTrait for fn(&32)` and
-            // `impl SomeTrait for fn(&'static u32)` at the same time which
-            // specify distinct values for Assoc. (See also #56105)
-            lt_op: |_| tcx.lifetimes.re_erased,
-            // Leave consts and types unchanged.
-            ct_op: |ct| ct,
-            ty_op: |ty| ty,
-        });
-        tcx.try_normalize_erasing_regions(param_env, ty).unwrap_or(ty)
+        tcx.try_normalize_erasing_regions(param_env, ty).unwrap_or(ty).fold_with(
+            &mut BottomUpFolder {
+                tcx,
+                // FIXME: We erase all late-bound lifetimes, but this is not fully correct.
+                // If you have a type like `<for<'a> fn(&'a u32) as SomeTrait>::Assoc`,
+                // this is not necessarily equivalent to `<fn(&'static u32) as SomeTrait>::Assoc`,
+                // since one may have an `impl SomeTrait for fn(&32)` and
+                // `impl SomeTrait for fn(&'static u32)` at the same time which
+                // specify distinct values for Assoc. (See also #56105)
+                lt_op: |_| tcx.lifetimes.re_erased,
+                // Leave consts and types unchanged.
+                ct_op: |ct| ct,
+                ty_op: |ty| ty,
+            },
+        )
     };
     tcx.infer_ctxt().enter(|infcx| infcx.can_eq(param_env, normalize(src), normalize(dest)).is_ok())
 }