From e623ff4e6ad3a35bd8b2acbb416e56981286400a Mon Sep 17 00:00:00 2001
From: Miguel Sofer <miguel.sofer@gmail.com>
Date: Sat, 10 Nov 2007 20:05:34 +0000
Subject: Improved failure comments for stack checks (mistachkin).

---
 ChangeLog          |  3 ++-
 generic/tclBasic.c | 25 +++++++++++++++----------
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 065efec..a3f6358 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,11 +2,12 @@
 
 	* generic/tclBasic.c:
 	* generic/tclInt.h:
+	* tests/interp.test (
 	* unix/tclUnixInit.c:
 	* win/tclWin32Dll.c: restore simpler behaviour for stack checking,
 	not adaptive to stack size changes after a thread is
 	launched. Consensus is that "nobody does that", and so it is not
-	worth the cost.
+	worth the cost. Improved failure comments (mistachkin).
 
 2007-11-10  Kevin Kenny  <kennykb@acm.org>
 
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 53cd4fd..893de64 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -14,7 +14,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclBasic.c,v 1.274 2007/11/10 19:01:34 msofer Exp $
+ * RCS: @(#) $Id: tclBasic.c,v 1.275 2007/11/10 20:05:34 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -340,13 +340,13 @@ static int stackGrowsDown = 1;
 #define GetCStackParams(iPtr) \
     stackGrowsDown = TclpGetCStackParams(&((iPtr)->stackBound))
 
-#define StackOverflow(iPtr, localIntPtr) \
+#define CheckCStack(iPtr, localIntPtr) \
     (stackGrowsDown \
-	    ? ((localIntPtr) < (iPtr)->stackBound) \
-	    : ((localIntPtr) > (iPtr)->stackBound) \
+	    ? ((localIntPtr) > (iPtr)->stackBound) \
+	    : ((localIntPtr) < (iPtr)->stackBound) \
     )
 #else /* stack check disabled: make them noops */
-#define StackOverflow(interp, localIntPtr) 0
+#define CheckCStack(interp, localIntPtr) 1
 #define GetCStackParams(iPtr) 
 #endif
 
@@ -3435,14 +3435,19 @@ TclInterpReady(
      * probably because of an infinite loop somewhere.
      */
 
-    if (((iPtr->numLevels) > iPtr->maxNestingDepth)
-	    || StackOverflow(iPtr, &localInt)) {
+    if (((iPtr->numLevels) <= iPtr->maxNestingDepth)
+	    && CheckCStack(iPtr, &localInt)) {
+	return TCL_OK;
+    }
+
+    if (!CheckCStack(iPtr, &localInt)) {
+	Tcl_AppendResult(interp,
+		"out of stack space (infinite loop?)", NULL);
+    } else {
 	Tcl_AppendResult(interp,
 		"too many nested evaluations (infinite loop?)", NULL);
-	return TCL_ERROR;
     }
-
-    return TCL_OK;
+    return TCL_ERROR;
 }
 
 /*
-- 
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