[4dbdd9af14] Plug mem leak when var unset trace re-creates namespace var. Thanks mr_calvin for report and fix.

2 files changed, 35 insertions, 5 deletions

diff --git a/generic/tclVar.c b/generic/tclVar.c
index 20bc208..48e09f6 100644
--- a/generic/tclVar.c
+++ b/generic/tclVar.c
@@ -4956,13 +4956,16 @@ TclDeleteNamespaceVars(
 	VarHashRefCount(varPtr)++;	/* Make sure we get to remove from
 					 * hash. */
 	Tcl_GetVariableFullName(interp, (Tcl_Var) varPtr, objPtr);
-	UnsetVarStruct(varPtr, NULL, iPtr, /* part1 */ objPtr, NULL, flags,
-		-1);
-	Tcl_DecrRefCount(objPtr);	/* Free no longer needed obj */
+	UnsetVarStruct(varPtr, NULL, iPtr, /* part1 */ objPtr,
+		NULL, flags, -1);
 
 	/*
-	 * Remove the variable from the table and force it undefined in case
-	 * an unset trace brought it back from the dead.
+	 * We just unset the variable. However, an unset trace might
+	 * have re-set it, or might have re-established traces on it.
+	 * This namespace and its vartable are going away unconditionally,
+	 * so we cannot let such things linger. That would be a leak.
+	 *
+	 * First we destroy all traces. ...
 	 */
 
 	if (TclIsVarTraced(varPtr)) {
@@ -4986,6 +4989,17 @@ TclDeleteNamespaceVars(
 		}
 	    }
 	}
+
+	/*
+	 * ...and then, if the variable still holds a value, we unset it
+	 * again. This time with no traces left, we're sure it goes away.
+	 */
+
+	if (!TclIsVarUndefined(varPtr)) {
+	    UnsetVarStruct(varPtr, NULL, iPtr, /* part1 */ objPtr,
+		    NULL, flags, -1);
+	}
+	Tcl_DecrRefCount(objPtr); /* free no longer needed obj */
 	VarHashRefCount(varPtr)--;
 	VarHashDeleteEntry(varPtr);
     }
diff --git a/tests/var.test b/tests/var.test
index 44e671a..9816d98 100644
--- a/tests/var.test
+++ b/tests/var.test
@@ -594,6 +594,22 @@ test var-8.2 {TclDeleteNamespaceVars, "unset" traces on ns delete are called wit
     list [namespace delete test_ns_var] $::info
 } -result {{} {::test_ns_var::v {} u}}
 
+test var-8.3 {TclDeleteNamespaceVars, mem leak} -constraints memory -setup {
+    proc ::t {a i o} {
+	set $a 321
+    }
+} -body {
+    leaktest {
+	namespace eval n {
+	    variable v 123
+	    trace variable v u ::t
+	}
+	namespace delete n
+    }
+} -cleanup {
+    rename ::t {}
+} -result 0
+
 test var-9.1 {behaviour of TclGet/SetVar simple get/set} -setup {
     catch {unset u}
     catch {unset v}