From 18ab705073faed3c01aa2f66a9d99d26d047c7bc Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Mon, 19 Sep 2022 14:00:34 +0000
Subject: [PATCH] Actually visit/fold the types inside CanonicalVarInfos

---
 compiler/rustc_middle/src/infer/canonical.rs | 23 ++++++++++++++------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_middle/src/infer/canonical.rs b/compiler/rustc_middle/src/infer/canonical.rs
index 4bad0950451..e46cf48142f 100644
--- a/compiler/rustc_middle/src/infer/canonical.rs
+++ b/compiler/rustc_middle/src/infer/canonical.rs
@@ -29,7 +29,7 @@
 use rustc_macros::HashStable;
 use smallvec::SmallVec;
 use std::iter;
-use std::ops::Index;
+use std::ops::{ControlFlow, Index};
 
 /// A "canonicalized" type `V` is one where all free inference
 /// variables have been rewritten to "canonical vars". These are
@@ -44,6 +44,21 @@ pub struct Canonical<'tcx, V> {
 
 pub type CanonicalVarInfos<'tcx> = &'tcx List<CanonicalVarInfo<'tcx>>;
 
+impl<'tcx> ty::TypeFoldable<'tcx> for CanonicalVarInfos<'tcx> {
+    fn try_fold_with<F: ty::FallibleTypeFolder<'tcx>>(
+        self,
+        folder: &mut F,
+    ) -> Result<Self, F::Error> {
+        ty::util::fold_list(self, folder, |tcx, v| tcx.intern_canonical_var_infos(v))
+    }
+}
+
+impl<'tcx> ty::TypeVisitable<'tcx> for CanonicalVarInfos<'tcx> {
+    fn visit_with<V: ty::TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
+        self.iter().try_for_each(|t| t.visit_with(visitor))
+    }
+}
+
 /// A set of values corresponding to the canonical variables from some
 /// `Canonical`. You can give these values to
 /// `canonical_value.substitute` to substitute them into the canonical
@@ -305,12 +320,6 @@ pub fn unchecked_map<W>(self, map_op: impl FnOnce(V) -> W) -> Canonical<'tcx, W>
     }
 }
 
-TrivialTypeTraversalImpls! {
-    for <'tcx> {
-        crate::infer::canonical::CanonicalVarInfos<'tcx>,
-    }
-}
-
 impl<'tcx> CanonicalVarValues<'tcx> {
     #[inline]
     pub fn len(&self) -> usize {