From a267c30fcdc48a602a57caaa3cf723009aad34aa Mon Sep 17 00:00:00 2001
From: Jon Siwek <jsiwek@ncsa.illinois.edu>
Date: Mon, 12 Sep 2011 13:16:48 -0500
Subject: [PATCH] Fix crash on exit (addresses #607).

MutableVal's destructor now checks if the global scope still exists
before trying to remove an identifier from it.
---
 src/Scope.cc | 2 +-
 src/Val.cc   | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/Scope.cc b/src/Scope.cc
index 196937d984..297446a9f0 100644
--- a/src/Scope.cc
+++ b/src/Scope.cc
@@ -219,5 +219,5 @@ Scope* current_scope()
 
 Scope* global_scope()
 	{
-	return scopes[0];
+	return scopes.length() == 0 ? 0 : scopes[0];
 	}
diff --git a/src/Val.cc b/src/Val.cc
index a7dba04550..0285cba645 100644
--- a/src/Val.cc
+++ b/src/Val.cc
@@ -638,14 +638,16 @@ MutableVal::~MutableVal()
 	{
 	for ( list<ID*>::iterator i = aliases.begin(); i != aliases.end(); ++i )
 		{
-		global_scope()->Remove((*i)->Name());
+		if ( global_scope() )
+			global_scope()->Remove((*i)->Name());
 		(*i)->ClearVal();	// just to make sure.
 		Unref((*i));
 		}
 
 	if ( id )
 		{
-		global_scope()->Remove(id->Name());
+		if ( global_scope() )
+			global_scope()->Remove(id->Name());
 		id->ClearVal(); // just to make sure.
 		Unref(id);
 		}