have better explanation for `relate_types`

1 files changed, 3 insertions, 5 deletions

diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index ed36ca6a29b..e7b1a489f5d 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -716,11 +716,9 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                 }
                 PlaceTy::from_ty(fty)
             }
-            ProjectionElem::Subtype(_) => PlaceTy::from_ty(Ty::new_error_with_message(
-                tcx,
-                self.last_span,
-                "ProjectionElem::Subtype shouldn't exist in borrowck",
-            )),
+            ProjectionElem::Subtype(_) => {
+                bug!("ProjectionElem::Subtype shouldn't exist in borrowck")
+            }
             ProjectionElem::OpaqueCast(ty) => {
                 let ty = self.sanitize_type(place, ty);
                 let ty = self.cx.normalize(ty, location);