From cc912b73a02978ef98876321877d1b923a4a22e5 Mon Sep 17 00:00:00 2001
From: dgp <dgp@users.sourceforge.net>
Date: Sat, 2 Sep 2017 20:40:44 +0000
Subject: Similar fix to Tcl_CreateCommand().

---
 generic/tclBasic.c | 85 ++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 54 insertions(+), 31 deletions(-)

diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 7c223e9..7f75892 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -1851,11 +1851,11 @@ Tcl_CreateCommand(
 {
     Interp *iPtr = (Interp *) interp;
     ImportRef *oldRefPtr = NULL;
-    Namespace *nsPtr, *dummy1, *dummy2;
-    Command *cmdPtr, *refCmdPtr;
+    Namespace *nsPtr;
+    Command *cmdPtr;
     Tcl_HashEntry *hPtr;
     const char *tail;
-    int isNew;
+    int isNew = 0, deleted = 0;
     ImportedCmdData *dataPtr;
 
     if (iPtr->flags & DELETED) {
@@ -1868,32 +1868,52 @@ Tcl_CreateCommand(
     }
 
     /*
-     * Determine where the command should reside. If its name contains
-     * namespace qualifiers, we put it in the specified namespace; otherwise,
-     * we always put it in the global namespace.
+     * If the command name we seek to create already exists, we need to
+     * delete that first.  That can be tricky in the presence of traces.
+     * Loop until we no longer find an existing command in the way, or
+     * until we've deleted one command and that didn't finish the job.
      */
 
-    if (strstr(cmdName, "::") != NULL) {
-	TclGetNamespaceForQualName(interp, cmdName, NULL,
-		TCL_CREATE_NS_IF_UNKNOWN, &nsPtr, &dummy1, &dummy2, &tail);
-	if ((nsPtr == NULL) || (tail == NULL)) {
-	    return (Tcl_Command) NULL;
-	}
-    } else {
-	nsPtr = iPtr->globalNsPtr;
-	tail = cmdName;
-    }
+    while (1) {
+        /*
+         * Determine where the command should reside. If its name contains
+         * namespace qualifiers, we put it in the specified namespace;
+	 * otherwise, we always put it in the global namespace.
+         */
 
-    hPtr = Tcl_CreateHashEntry(&nsPtr->cmdTable, tail, &isNew);
-    if (!isNew) {
+        if (strstr(cmdName, "::") != NULL) {
+	    Namespace *dummy1, *dummy2;
+
+	    TclGetNamespaceForQualName(interp, cmdName, NULL,
+		    TCL_CREATE_NS_IF_UNKNOWN, &nsPtr, &dummy1, &dummy2, &tail);
+	    if ((nsPtr == NULL) || (tail == NULL)) {
+	        return (Tcl_Command) NULL;
+	    }
+        } else {
+	    nsPtr = iPtr->globalNsPtr;
+	    tail = cmdName;
+        }
+
+        hPtr = Tcl_CreateHashEntry(&nsPtr->cmdTable, tail, &isNew);
+
+        if (isNew || deleted) {
+	    /*
+	     * isNew - No conflict with existing command.
+	     * deleted - We've already deleted a conflicting command
+	     */
+	    break;
+        }
+
+	/* An existing command conflicts. Try to delete it.. */
+	cmdPtr = Tcl_GetHashValue(hPtr);
+	
 	/*
-	 * Command already exists. Delete the old one. Be careful to preserve
+	 * Be careful to preserve
 	 * any existing import links so we can restore them down below. That
 	 * way, you can redefine a command and its import status will remain
 	 * intact.
 	 */
 
-	cmdPtr = Tcl_GetHashValue(hPtr);
 	cmdPtr->refCount++;
 	if (cmdPtr->importRefPtr) {
 	    cmdPtr->flags |= CMD_REDEF_IN_PROGRESS;
@@ -1906,18 +1926,21 @@ Tcl_CreateCommand(
 	    cmdPtr->importRefPtr = NULL;
 	}
 	TclCleanupCommandMacro(cmdPtr);
+	deleted = 1;
+    }
 
-	hPtr = Tcl_CreateHashEntry(&nsPtr->cmdTable, tail, &isNew);
-	if (!isNew) {
-	    /*
-	     * If the deletion callback recreated the command, just throw away
-	     * the new command (if we try to delete it again, we could get
-	     * stuck in an infinite loop).
-	     */
+    if (!isNew) {
+	/*
+	 * If the deletion callback recreated the command, just throw away
+	 * the new command (if we try to delete it again, we could get
+	 * stuck in an infinite loop).
+	 */
+
+	ckfree((char *) Tcl_GetHashValue(hPtr));
+    }
+
+    if (!deleted) {
 
-	     ckfree((char *) Tcl_GetHashValue(hPtr));
-	}
-    } else {
 	/*
 	 * The list of command exported from the namespace might have changed.
 	 * However, we do not need to recompute this just yet; next time we
@@ -1952,7 +1975,7 @@ Tcl_CreateCommand(
     if (oldRefPtr != NULL) {
 	cmdPtr->importRefPtr = oldRefPtr;
 	while (oldRefPtr != NULL) {
-	    refCmdPtr = oldRefPtr->importedCmdPtr;
+	    Command *refCmdPtr = oldRefPtr->importedCmdPtr;
 	    dataPtr = refCmdPtr->objClientData;
 	    dataPtr->realCmdPtr = cmdPtr;
 	    oldRefPtr = oldRefPtr->nextPtr;
-- 
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