From 9db190eb31d4adc412d50bc03574951f9a1f9dae Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Fri, 14 Jan 2011 12:47:10 +0000
Subject: * builtins.substring: if "start" is beyond the end of the string,  
 return the empty string.

---
 src/libexpr/primops.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'src/libexpr/primops.cc')

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index a4812de06519..3e955ea3fe09 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -965,7 +965,7 @@ static void prim_substring(EvalState & state, Value * * args, Value & v)
 
     if (start < 0) throw EvalError("negative start position in `substring'");
 
-    mkString(v, string(s, start, len), context);
+    mkString(v, start >= s.size() ? "" : string(s, start, len), context);
 }
 
 
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