PMIx_Group_construct - handle error returns

The error return code from PMIx_Group_construct was not being handled at all.
This PR fixes this issue.

In cases where the process is running without a PMIx server, for instance in a singleton
program which has not invoked MPI_Comm_spawn, and it uses MPI_Comm_create_from_group
the following error hep message is emitted:

--------------------------------------------------------------------------

Your application has invoked an MPI function that is not supported in
this environment.

  MPI function: MPI_Comm_from_group/MPI_Intercomm_from_groups
  Reason:       PMIx server unreachable

--------------------------------------------------------------------------

If a PMIx implementation is being used that does not support PMIx_Group_construct,
the following help message is emitted if the code invokes MPI_Comm_create_from_group
or MPI_Intercomm_create_from_groups:

--------------------------------------------------------------------------

Your application has invoked an MPI function that is not supported in
this environment.

  MPI function: MPI_Comm_from_group/MPI_Intercomm_from_groups
  Reason:       PMIx server does not support PMIx Group operations

--------------------------------------------------------------------------

Related to #10736

Signed-off-by: Howard Pritchard <howardp@lanl.gov>

Author: hppritcha

ompi/communicator/comm_cid.c

@@ -310,11 +310,13 @@ static int ompi_comm_ext_cid_new_block (ompi_communicator_t *newcomm, ompi_commu
 {
     pmix_info_t pinfo, *results = NULL;
     size_t nresults;
-    opal_process_name_t *name_array;
+    opal_process_name_t *name_array = NULL;
     char *tag = NULL;
-    size_t proc_count, cid_base = 0UL;
+    size_t proc_count;
+    size_t cid_base;
     int rc, leader_rank;
-    pmix_proc_t *procs;
+    int ret = OMPI_SUCCESS;
+    pmix_proc_t *procs = NULL;
 
     rc = ompi_group_to_proc_name_array (newcomm->c_local_group, &name_array, &proc_count);
     if (OPAL_UNLIKELY(OMPI_SUCCESS != rc)) {
@@ -345,20 +347,64 @@ static int ompi_comm_ext_cid_new_block (ompi_communicator_t *newcomm, ompi_commu
 
     rc = PMIx_Group_construct(tag, procs, proc_count, &pinfo, 1, &results, &nresults);
     PMIX_INFO_DESTRUCT(&pinfo);
+    if(PMIX_SUCCESS != rc) {
+       char msg_string[1024];
+        switch (rc) {
+        case PMIX_ERR_UNREACH:
+            sprintf(msg_string,"PMIx server unreachable");
+            opal_show_help("help-comm.txt",
+                           "MPI function not supported",
+                           true,
+                           "MPI_Comm_from_group/MPI_Intercomm_from_groups",
+                           msg_string);
+
+            ret = MPI_ERR_UNSUPPORTED_OPERATION;
+            break;
+        case PMIX_ERR_NOT_SUPPORTED:
+            sprintf(msg_string,"PMIx server does not support PMIx Group operations");
+            opal_show_help("help-comm.txt",
+                           "MPI function not supported",
+                           true,
+                           "MPI_Comm_from_group/MPI_Intercomm_from_groups",
+                           msg_string);
+            ret = MPI_ERR_UNSUPPORTED_OPERATION;
+            break;
+        default:
+            ret = opal_pmix_convert_status(rc);
+            break;
+        } 
+        goto fn_exit;
+    }
 
     if (NULL != results) {
         PMIX_VALUE_GET_NUMBER(rc, &results[0].value, cid_base, size_t);
-        PMIX_INFO_FREE(results, nresults);
     }
 
-    PMIX_PROC_FREE(procs, proc_count);
-    free (name_array);
-
     rc = PMIx_Group_destruct (tag, NULL, 0);
+    if(PMIX_SUCCESS != rc) {
+        ret = opal_pmix_convert_status(rc);
+        goto fn_exit;
+    }
 
     ompi_comm_extended_cid_block_initialize (new_block, cid_base, 0, 0);
 
-    return OMPI_SUCCESS;
+fn_exit:
+    if (NULL != results) {
+        PMIX_INFO_FREE(results, nresults);
+        results = NULL;
+    }
+
+    if(NULL != procs) {
+        PMIX_PROC_FREE(procs, proc_count);
+        procs = NULL;
+    }
+
+    if(NULL != name_array) {
+        free (name_array);
+        name_array = NULL;
+    }
+
+    return ret;
 }
 
 static int ompi_comm_nextcid_ext_nb (ompi_communicator_t *newcomm, ompi_communicator_t *comm,