Tests and fix for [menubutton ... -textvariable].

2 files changed, 49 insertions, 1 deletions

diff --git a/generic/tkMenubutton.c b/generic/tkMenubutton.c
index 1a4d5ae..9faa263 100644
--- a/generic/tkMenubutton.c
+++ b/generic/tkMenubutton.c
@@ -887,7 +887,27 @@ MenuButtonTextVarProc(
      */
 
     if (flags & TCL_TRACE_UNSETS) {
-	if ((flags & TCL_TRACE_DESTROYED) && !(flags & TCL_INTERP_DESTROYED)) {
+        if (!Tcl_InterpDeleted(interp) && mbPtr->textVarName) {
+            ClientData probe = NULL;
+
+            do {
+                probe = Tcl_VarTraceInfo(interp,
+                        mbPtr->textVarName,
+                        TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
+                        MenuButtonTextVarProc, probe);
+                if (probe == (ClientData)mbPtr) {
+                    break;
+                }
+            } while (probe);
+            if (probe) {
+                /*
+                 * We were able to fetch the unset trace for our
+                 * textVarName, which means it is not unset and not
+                 * the cause of this unset trace. Instead some outdated
+                 * former variable must be, and we should ignore it.
+                 */
+                return NULL;
+            }
 	    Tcl_SetVar2(interp, mbPtr->textVarName, NULL, mbPtr->text,
 		    TCL_GLOBAL_ONLY);
 	    Tcl_TraceVar2(interp, mbPtr->textVarName, NULL,
diff --git a/tests/menubut.test b/tests/menubut.test
index 6efdb0f..93b2482 100644
--- a/tests/menubut.test
+++ b/tests/menubut.test
@@ -747,6 +747,34 @@ test menubutton-8.1 {menubutton vs hidden commands} -body {
     expr {$res1 eq $res2}
 } -result 1
 
+test menubutton-9.1 {Bug [5d991b822e]} {
+    # Want this not to segfault, or write to variable with empty name
+    set var INIT
+    menubutton .b -textvariable var
+    trace add variable var unset {apply {args {
+        .b configure -textvariable {}
+    }}}
+    pack .b
+    bind .b <Configure> {unset var}
+    update
+    destroy .b
+    info exists {}
+} 0
+test menubutton-9.2 {Bug [5d991b822e]} {
+    # Want this not to leak traces
+    set var INIT
+    menubutton .b -textvariable var
+    trace add variable var unset {apply {args {
+        .b configure -textvariable new
+    }}}
+    pack .b
+    bind .b <Configure> {unset -nocomplain var}
+    update
+    destroy .b
+    unset new
+} {}
+
+
 
 
 deleteWindows