Sorry, previous commit was in the wrong directory. This is the real fix (have

to undo 1822).

The verification of recvcount==0 and rank = root was braking
inter-communicator scatter, since the root (root==MPI_ROOT) might very well
have recvcount=0. The same fix has been applied to gather.c just the other way
round. 
 
Fixes the bug reported on the mainling list by Martin Audet. If there is a
1.2.7 this fix might be worthwhile porting it over.

Please note, that while the test works now for basic and for inter, we get a
0byte malloc warning from the inter module, which we still have to fix in a
separate patch.

This commit was SVN r18123.

ompi/mpi/c/gather.c

@@ -10,6 +10,7 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2006-2007 Cisco Systems, Inc.  All rights reserved.
+ * Copyright (c) 2008      University of Houston.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -123,7 +124,7 @@ int MPI_Gather(void *sendbuf, int sendcount, MPI_Datatype sendtype,
 
     /* Do we need to do anything? */
 
-    if ((0 == sendcount &&
+    if ((0 == sendcount && MPI_ROOT != root && 
          (ompi_comm_rank(comm) != root ||
           (ompi_comm_rank(comm) == root && MPI_IN_PLACE != sendbuf))) ||
         (ompi_comm_rank(comm) == root && MPI_IN_PLACE == sendbuf && 

ompi/mpi/c/scatter.c

@@ -10,6 +10,7 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2006-2007 Cisco Systems, Inc.  All rights reserved.
+ * Copyright (c) 2008      University of Houston.  All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -118,8 +119,8 @@ int MPI_Scatter(void *sendbuf, int sendcount, MPI_Datatype sendtype,
 
     /* Do we need to do anything? */
 
-    if ((0 == recvcount &&
-         (ompi_comm_rank(comm) != root ||
+    if ((0 == recvcount && MPI_ROOT != root && 
+         (ompi_comm_rank(comm) != root || 
           (ompi_comm_rank(comm) == root && MPI_IN_PLACE != recvbuf))) ||
         (ompi_comm_rank(comm) == root && MPI_IN_PLACE == recvbuf &&
          0 == sendcount)) {