Added a new test for checking for zero-byte window creations.

MPICH currently has a bug that causes it to abort when all processes
provide zero bytes to the window allocation routine.  While it can be
considered a user error, the MPI-3 standard does not explicitly
disallow this case.

test/mpi/rma/Makefile.am

@@ -83,6 +83,7 @@ noinst_PROGRAMS =          \
     win_shared             \
     win_shared_noncontig   \
     win_shared_noncontig_put \
+    win_zero               \
     win_dynamic_acc        \
     get_acc_local          \
     compare_and_swap       \

test/mpi/rma/testlist

@@ -68,6 +68,7 @@ manyrma2 2 timeLimit=500
 win_shared 4 mpiversion=3.0
 win_shared_noncontig 4 mpiversion=3.0
 win_shared_noncontig_put 4 mpiversion=3.0
+win_zero 4 mpiversion=3.0
 win_dynamic_acc 4 mpiversion=3.0
 get_acc_local 1 mpiversion=3.0
 linked_list 4 mpiversion=3.0

test/mpi/rma/win_zero.c

+/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
+/*
+ *  (C) 2001 by Argonne National Laboratory.
+ *      See COPYRIGHT in top-level directory.
+ */
+
+/* test MPI_WIN_ALLOCATE_SHARED when size of total shared memory region is 0. */
+
+#include "mpi.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char **argv)
+{
+    MPI_Win win;
+    void *win_buf = NULL;
+    int world_rank, shm_rank;
+    MPI_Comm shm_comm;
+
+    MPI_Init(&argc, &argv);
+    MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
+
+    MPI_Comm_split_type(MPI_COMM_WORLD, MPI_COMM_TYPE_SHARED, world_rank, MPI_INFO_NULL, &shm_comm);
+
+    MPI_Comm_rank(shm_comm, &shm_rank);
+
+    /* Some ranks allocate zero bytes */
+    if (shm_rank % 2 == 0)
+        MPI_Win_allocate_shared(0, sizeof(char), MPI_INFO_NULL, shm_comm, &win_buf, &win);
+    else
+        MPI_Win_allocate_shared(1, sizeof(char), MPI_INFO_NULL, shm_comm, &win_buf, &win);
+    MPI_Win_free(&win);
+
+    if (world_rank % 2 == 0)
+        MPI_Win_allocate(0, sizeof(char), MPI_INFO_NULL, MPI_COMM_WORLD, &win_buf, &win);
+    else
+        MPI_Win_allocate(1, sizeof(char), MPI_INFO_NULL, MPI_COMM_WORLD, &win_buf, &win);
+    MPI_Win_free(&win);
+
+    win_buf = NULL;
+    if (world_rank % 2 == 0)
+        MPI_Win_create(NULL, 0, sizeof(char), MPI_INFO_NULL, MPI_COMM_WORLD, &win);
+    else {
+        win_buf = (void *) malloc(sizeof(char));
+        MPI_Win_create(win_buf, 1, sizeof(char), MPI_INFO_NULL, MPI_COMM_WORLD, &win);
+    }
+    MPI_Win_free(&win);
+    if (win_buf)
+        free(win_buf);
+
+    /* All ranks allocate zero bytes */
+    MPI_Win_allocate_shared(0, sizeof(char), MPI_INFO_NULL, shm_comm, &win_buf, &win);
+    MPI_Win_free(&win);
+    MPI_Win_allocate(0, sizeof(char), MPI_INFO_NULL, MPI_COMM_WORLD, &win_buf, &win);
+    MPI_Win_free(&win);
+    MPI_Win_create(NULL, 0, sizeof(char), MPI_INFO_NULL, MPI_COMM_WORLD, &win);
+    MPI_Win_free(&win);
+
+    MPI_Comm_free(&shm_comm);
+
+    if (world_rank == 0)
+        printf(" No Errors\n");
+
+    MPI_Finalize();
+
+    return 0;
+
+}