[mod4-flavours]$ module purge
[mod4-flavours]$ module load pgi/19.4
[mod4-flavours]$ module load openmpi/4.0
[mod4-flavours]$ module list
Currently Loaded Modulefiles:
 1) pgi/19.4   2) openmpi/4.0
[mod4-flavours]$ mpirun
mpirun (openmpi/4.0, pgi/19.4)
[mod4-flavours]$ module unload openmpi
[mod4-flavours]$ module switch pgi intel/2019
[mod4-flavours]$ module load openmpi/4.0
[mod4-flavours]$ module list
Currently Loaded Modulefiles:
 1) intel/2019   2) openmpi/4.0
[mod4-flavours]$ mpirun
mpirun (openmpi/4.0, intel/2019)
[mod4-flavours]$ module unload openmpi
[mod4-flavours]$ module switch intel gnu/9.1.0
[mod4-flavours]$ module load openmpi/4.0
[mod4-flavours]$ mpirun
mpirun (openmpi/4.0, gcc/9.1.0)
[mod4-flavours]$ module unload openmpi
[mod4-flavours]$ module switch gnu gnu/8.2.0
[mod4-flavours]$ module load openmpi/4.0
openmpi/4.0 - no flavour compatible with modules 'gnu/8.2.0'

Loading openmpi/4.0
  ERROR: Module evaluation aborted
[mod4-flavours]$ module list
Currently Loaded Modulefiles:
 1) gnu/8.2.0
