From 003b1699c0044aef757c9c32df13a529fd4c485b Mon Sep 17 00:00:00 2001
From: Michael Woerister <michaelwoerister@posteo.net>
Date: Tue, 15 Nov 2016 11:55:34 -0500
Subject: [PATCH] Add error message when not finding the ICH of a DepNode.

---
 src/librustc_incremental/calculate_svh/mod.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/librustc_incremental/calculate_svh/mod.rs b/src/librustc_incremental/calculate_svh/mod.rs
index c08519090d2..0339f488272 100644
--- a/src/librustc_incremental/calculate_svh/mod.rs
+++ b/src/librustc_incremental/calculate_svh/mod.rs
@@ -88,7 +88,12 @@ impl<'a> ::std::ops::Index<&'a DepNode<DefId>> for IncrementalHashesMap {
     type Output = Fingerprint;
 
     fn index(&self, index: &'a DepNode<DefId>) -> &Fingerprint {
-        &self.hashes[index]
+        match self.hashes.get(index) {
+            Some(fingerprint) => fingerprint,
+            None => {
+                bug!("Could not find ICH for {:?}", index);
+            }
+        }
     }
 }