[16828b3744] [vwait] *must* successfully undo its variable trace, or else

it risks corrupting memory.  Namespace teardown complexities were giving
the traces an opportunity to survive.  Added another (arguably better)
Tcl_UntraceVar() call to be sure we avoid this problem.

2 files changed, 30 insertions, 0 deletions

diff --git a/generic/tclEvent.c b/generic/tclEvent.c
index 8305410..b0b8188 100644
--- a/generic/tclEvent.c
+++ b/generic/tclEvent.c
@@ -1462,6 +1462,8 @@ VwaitVarProc(
     int *donePtr = clientData;
 
     *donePtr = 1;
+    Tcl_UntraceVar(interp, name1, TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
+	    VwaitVarProc, clientData);
     return NULL;
 }
 
diff --git a/tests/event.test b/tests/event.test
index 0d1b06c..207c799 100644
--- a/tests/event.test
+++ b/tests/event.test
@@ -583,6 +583,34 @@ test event-11.6 {Tcl_VwaitCmd procedure: round robin scheduling, same source} {
     removeFile $test2file
     list $x $y $z
 } {3 3 done}
+test event-11.7 {Bug 16828b3744} {
+    after idle {
+	set ::t::v 1
+	namespace delete ::t
+    }
+    namespace eval ::t {
+	vwait ::t::v
+    }
+} {}
+test event-11.8 {Bug 16828b3744} -setup {
+    oo::class create A {
+	variable continue
+    
+	method start {} {
+           after idle [self] destroy
+        
+           set continue 0
+           vwait [namespace current]::continue
+	}
+	destructor {
+           set continue 1
+	}	
+    }
+} -body {
+    [A new] start
+} -cleanup {
+    A destroy
+} -result {}
 
 test event-12.1 {Tcl_UpdateCmd procedure} -returnCodes error -body {
     update a b