Adapt `TypeFolder` implementors to return a `Result`

Co-authored-by: Alan Egerton <eggyal@gmail.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/librustdoc/clean/auto_trait.rs b/src/librustdoc/clean/auto_trait.rs
index 2ccf17387d1..3a6f611660e 100644
--- a/src/librustdoc/clean/auto_trait.rs
+++ b/src/librustdoc/clean/auto_trait.rs
@@ -714,11 +714,11 @@ impl<'a, 'tcx> TypeFolder<'tcx> for RegionReplacer<'a, 'tcx> {
         self.tcx
     }
 
-    fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
-        (match *r {
+    fn fold_region(&mut self, r: ty::Region<'tcx>) -> Result<ty::Region<'tcx>, Self::Error> {
+        Ok((match *r {
             ty::ReVar(vid) => self.vid_to_region.get(&vid).cloned(),
             _ => None,
         })
-        .unwrap_or_else(|| r.super_fold_with(self))
+        .unwrap_or_else(|| r.super_fold_with(self).into_ok()))
     }
 }