[a4494e28ed] Use flag bit instead of NULL pointer to suppress

              teardown list of imported commands when the original command
              gets re-created. This prevents the panic otherwise possible when
              the invalid state represented by the NULL pointer is encountered
              during a command delete trace.

3 files changed, 39 insertions, 10 deletions

diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 46b532b..2a334c4 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -2085,10 +2085,19 @@ Tcl_CreateCommand(
 	 */
 
 	cmdPtr = Tcl_GetHashValue(hPtr);
-	oldRefPtr = cmdPtr->importRefPtr;
-	cmdPtr->importRefPtr = NULL;
+	cmdPtr->refCount++;
+	if (cmdPtr->importRefPtr) {
+	    cmdPtr->flags |= CMD_REDEF_IN_PROGRESS;
+	}
 
 	Tcl_DeleteCommandFromToken(interp, (Tcl_Command) cmdPtr);
+
+	if (cmdPtr->flags & CMD_REDEF_IN_PROGRESS) {
+	    oldRefPtr = cmdPtr->importRefPtr;
+	    cmdPtr->importRefPtr = NULL;
+	}
+	TclCleanupCommandMacro(cmdPtr);
+
 	hPtr = Tcl_CreateHashEntry(&nsPtr->cmdTable, tail, &isNew);
 	if (!isNew) {
 	    /*
@@ -2272,10 +2281,19 @@ Tcl_CreateObjCommand(
 	 * intact.
 	 */
 
-	oldRefPtr = cmdPtr->importRefPtr;
-	cmdPtr->importRefPtr = NULL;
+	cmdPtr->refCount++;
+	if (cmdPtr->importRefPtr) {
+	    cmdPtr->flags |= CMD_REDEF_IN_PROGRESS;
+	}
 
 	Tcl_DeleteCommandFromToken(interp, (Tcl_Command) cmdPtr);
+
+	if (cmdPtr->flags & CMD_REDEF_IN_PROGRESS) {
+	    oldRefPtr = cmdPtr->importRefPtr;
+	    cmdPtr->importRefPtr = NULL;
+	}
+	TclCleanupCommandMacro(cmdPtr);
+
 	hPtr = Tcl_CreateHashEntry(&nsPtr->cmdTable, tail, &isNew);
 	if (!isNew) {
 	    /*
@@ -3117,12 +3135,13 @@ Tcl_DeleteCommandFromToken(
      * commands were created that refer back to this command. Delete these
      * imported commands now.
      */
-
-    for (refPtr = cmdPtr->importRefPtr; refPtr != NULL;
-	    refPtr = nextRefPtr) {
-	nextRefPtr = refPtr->nextPtr;
-	importCmd = (Tcl_Command) refPtr->importedCmdPtr;
-	Tcl_DeleteCommandFromToken(interp, importCmd);
+    if (!(cmdPtr->flags & CMD_REDEF_IN_PROGRESS)) {
+	for (refPtr = cmdPtr->importRefPtr; refPtr != NULL;
+		refPtr = nextRefPtr) {
+	    nextRefPtr = refPtr->nextPtr;
+	    importCmd = (Tcl_Command) refPtr->importedCmdPtr;
+	    Tcl_DeleteCommandFromToken(interp, importCmd);
+	}
     }
 
     /*
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 7da0b7f..2aa1725 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -1686,6 +1686,7 @@ typedef struct Command {
 #define CMD_TRACE_ACTIVE	    0x2
 #define CMD_HAS_EXEC_TRACES	    0x4
 #define CMD_COMPILES_EXPANDED	    0x8
+#define CMD_REDEF_IN_PROGRESS	    0x10
 
 /*
  *----------------------------------------------------------------
diff --git a/tests/namespace.test b/tests/namespace.test
index f6688f1..8c4b81c 100644
--- a/tests/namespace.test
+++ b/tests/namespace.test
@@ -558,6 +558,15 @@ test namespace-13.1 {DeleteImportedCmd, deletes imported cmds} {
         lappend l [info commands ::test_ns_import::*]
     }
 } {::test_ns_import::cmd1 {}}
+test namespace-13.2 {DeleteImportedCmd, Bug a4494e28ed} {
+    # Will panic if still buggy
+    namespace eval src {namespace export foo; proc foo {} {}}
+    namespace eval dst {namespace import [namespace parent]::src::foo}
+    trace add command src::foo delete \
+        "[list namespace delete [namespace current]::dst] ;#"
+    proc src::foo {} {}
+    namespace delete src
+} {}
 
 test namespace-14.1 {TclGetNamespaceForQualName, absolute names} {
     catch {namespace delete {*}[namespace children :: test_ns_*]}