From 4fba7d33d614a78d1d641dc9b65d4a04e0d36e8a Mon Sep 17 00:00:00 2001
From: Oliver Schneider <github35764891676564198441@oli-obk.de>
Date: Sun, 22 Jul 2018 12:17:35 +0200
Subject: [PATCH] Mark an unreachable case as a bug instead of attempting to
 show an error to the user

---
 src/librustc_mir/borrow_check/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs
index cd5ed0e70a3..89bbc42df04 100644
--- a/src/librustc_mir/borrow_check/mod.rs
+++ b/src/librustc_mir/borrow_check/mod.rs
@@ -1853,7 +1853,7 @@ fn is_mutable<'d>(
                 }
             }
             // promoteds may never be mutated
-            Place::Promoted(_) => Err(place),
+            Place::Promoted(_) => bug!("encountered mutable promoted"),
             Place::Static(ref static_) => {
                 if self.tcx.is_static(static_.def_id) != Some(hir::Mutability::MutMutable) {
                     Err(place)
-- 
2.44.0