From ae368b81bc5c10ebb516e0d1be58ca09b7d31b22 Mon Sep 17 00:00:00 2001
From: janmroczkowski <jan.mroczkowski@diffblue.com>
Date: Mon, 4 Dec 2017 09:54:06 +0000
Subject: [PATCH] Fix to unified_difft::lcss for it not to error on iterator
 check

---
 src/goto-diff/unified_diff.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/goto-diff/unified_diff.cpp b/src/goto-diff/unified_diff.cpp
index e21bd88bd66..70343563e58 100644
--- a/src/goto-diff/unified_diff.cpp
+++ b/src/goto-diff/unified_diff.cpp
@@ -266,7 +266,8 @@ unified_difft::differencest unified_difft::lcss(
     {
       differences.push_back(differencet::DELETED);
       --i;
-      --old_rit;
+      if(old_goto_program.instructions.begin()!=old_rit)
+        --old_rit;
     }
     else if(instructions_equal(*old_rit, *new_rit))
     {
@@ -286,7 +287,8 @@ unified_difft::differencest unified_difft::lcss(
     {
       differences.push_back(differencet::NEW);
       --j;
-      --new_rit;
+      if(new_goto_program.instructions.begin()!=new_rit)
+        --new_rit;
     }
   }