From f67ee0f315c82e08c115704c164c6942c478e148 Mon Sep 17 00:00:00 2001
From: slava <slava@factorcode.org>
Date: Wed, 15 Nov 2006 02:40:54 +0000
Subject: [PATCH] Kick off 0.87 with better callstack underflow handling

---
 TODO.FACTOR.txt        | 1 -
 library/version.factor | 2 +-
 vm/factor.c            | 2 --
 vm/run.c               | 7 ++++++-
 4 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/TODO.FACTOR.txt b/TODO.FACTOR.txt
index 203dd0616c..f20c11ef03 100644
--- a/TODO.FACTOR.txt
+++ b/TODO.FACTOR.txt
@@ -38,7 +38,6 @@
 - allow rebinding styles
 - fix windows gcc issue
 - robustify stepper -- see if step back past a throw works
-- empty callstack: should throw an exception instead of being a critical error
 
 + ui:
 
diff --git a/library/version.factor b/library/version.factor
index 8ec0ddbe43..24f16606fc 100644
--- a/library/version.factor
+++ b/library/version.factor
@@ -1,2 +1,2 @@
 IN: kernel
-: version "0.86" ;
+: version "0.87" ;
diff --git a/vm/factor.c b/vm/factor.c
index 529b166a3f..6a7474dc8f 100644
--- a/vm/factor.c
+++ b/vm/factor.c
@@ -104,7 +104,5 @@ int main(int argc, char** argv)
 
 	run_toplevel();
 
-	critical_error("run_toplevel() returned due to empty callstack",0);
-
 	return 0;
 }
diff --git a/vm/run.c b/vm/run.c
index c8bcea5eee..bc1b8e0fae 100644
--- a/vm/run.c
+++ b/vm/run.c
@@ -69,7 +69,12 @@ void interpreter_loop(void)
 		if(callframe_scan == callframe_end)
 		{
 			if(cs_bot - cs == CELLS)
-				return;
+			{
+				if(stack_chain->next)
+					return;
+
+				general_error(ERROR_CS_UNDERFLOW,F,F,false);
+			}
 
 			callframe_end = get(cs);
 			callframe_scan = get(cs - CELLS);