Fix [Bug 1671138]

3 files changed, 30 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index ff709a9..2e8a2d0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2007-03-01  Donal K. Fellows  <donal.k.fellows@man.ac.uk>
+
+	* generic/tclCompCmds.c (TclCompileForeachCmd): Prevent an unexpected
+	* tests/foreach.test (foreach-9.1):		infinite loop when the
+	variable list is empty and the foreach is compiled. [Bug 1671138]
+
 2007-02-22  Andreas Kupries  <andreask@activestate.com>
 
 	* tests/pkg.test: Added tests for the case of an alpha package
diff --git a/generic/tclCompCmds.c b/generic/tclCompCmds.c
index 0737ab2..9c20bac 100644
--- a/generic/tclCompCmds.c
+++ b/generic/tclCompCmds.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclCompCmds.c,v 1.39.2.4 2006/11/28 22:20:00 andreas_kupries Exp $
+ * RCS: @(#) $Id: tclCompCmds.c,v 1.39.2.5 2007/03/01 10:16:10 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -894,6 +894,18 @@ TclCompileForeachCmd(interp, parsePtr, envPtr)
 		    goto done;
 		}
 		numVars = varcList[loopIndex];
+
+		/*
+		 * If the variable list is empty, we can enter an infinite
+		 * loop when the interpreted version would not. Take care to
+		 * ensure this does not happen. [Bug 1671138]
+		 */
+
+		if (numVars == 0) {
+		    code = TCL_ERROR;
+		    goto done;
+		}
+
 		for (j = 0;  j < numVars;  j++) {
 		    CONST char *varName = varvList[loopIndex][j];
 		    if (!TclIsLocalScalar(varName, (int) strlen(varName))) {
diff --git a/tests/foreach.test b/tests/foreach.test
index 0ab6340..ee90ce2 100644
--- a/tests/foreach.test
+++ b/tests/foreach.test
@@ -10,7 +10,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: foreach.test,v 1.8.8.1 2003/03/27 13:11:01 dkf Exp $
+# RCS: @(#) $Id: foreach.test,v 1.8.8.2 2007/03/01 10:16:10 dkf Exp $
 
 if {[lsearch [namespace children] ::tcltest] == -1} {
     package require tcltest
@@ -233,6 +233,16 @@ test foreach-7.1 {delayed substitution of body} {
     foo
 } {0}
 
+# [Bug 1671138]; infinite loop with empty var list in bytecompiled version
+test foreach-9.1 {compiled empty var list} {
+    proc foo {} {
+	foreach {} x {
+	    error "reached body"
+	}
+    }
+    list [catch { foo } msg] $msg
+} {1 {foreach varlist is empty}}
+
 # cleanup
 catch {unset a}
 catch {unset x}