Domain-index lookup-table initialisations in non-MPI configurations

Context

A PSyclone developer has reported that the GYRE_PISCES reference configuration of NEMO version 4.2 compiled for execution without MPI (pre-processing key key_mpi_off defined) segfaults.

Analysis

The reporter has tracked down the segfault to an access of the unallocated array mig0 in subroutine usr_def_hgr of module usrdef_hgr.

Fix

The reporter has kindly suggested the inclusion of CALL init_locglo in the non-MPI pre-processed variant of src/OCE/LBC/mppini.F90 to ensure array mig0 is allocated before being accessed in non-MPI configurations. Indeed, with the source-code modification

--- a/src/OCE/LBC/mppini.F90
+++ b/src/OCE/LBC/mppini.F90
@@ -86,6 +86,7 @@ CONTAINS
       l_IdoNFold = l_NFold                         ! is this process doing North fold?
       !
       CALL init_doloop                       ! set start/end indices or do-loop depending on the halo width value (nn_hls)
+      CALL init_locglo
       !
       IF(lwp) THEN
          WRITE(numout,*)

the non-MPI GYRE_PISCES configuration of NEMO version 4.2 is viable and successfully passes the standard SETTE restartability and reproducibility tests.