Use a global property for indicating openmpi.

Using just a variable to indicate openmpi did not work reliably with
all generators, i.e. at least with ninja the variable was not set
in the top-level CMakeLists.txt and therefore additional options
were not set leading to test failures.

Author: vehre

CMakeLists.txt

@@ -644,6 +644,11 @@ define_property(TARGET
   FULL_DOCS "Property to mark executable targets run as tests that they require 2^n images."
   )
 
+#-------------------------------------------------------------------------------------
+# Add global openmpi property, because using a variable an setting in parent scope did
+# not work as expected, i.e., not at all, on Linux Fedora 39.
+#-------------------------------------------------------------------------------------
+define_property(GLOBAL PROPERTY openmpi BRIEF_DOCS "True when mpi is openMPI.")
 
 #-------------------------------
 # Recurse into the src directory
@@ -715,6 +720,7 @@ function(add_caf_test name num_caf_img test_target)
     endif()
   endif()
   # Add a host file for OMPI
+  get_property(openmpi GLOBAL PROPERTY openmpi)
   if ( openmpi )
     set(test_parameters --hostfile ${CMAKE_BINARY_DIR}/hostfile)
   endif()

src/runtime-libraries/mpi/CMakeLists.txt

@@ -147,7 +147,7 @@ execute_process(COMMAND ${MPIEXEC_EXECUTABLE} --version
   OUTPUT_VARIABLE mpi_version_out)
 if (mpi_version_out MATCHES "[Oo]pen[ -][Mm][Pp][Ii]")
   message( STATUS "OpenMPI detected")
-  set ( openmpi true PARENT_SCOPE)
+  set_property(GLOBAL PROPERTY openmpi true)
   # Write out a host file because OMPI's mpiexec is dumb
   file(WRITE ${CMAKE_BINARY_DIR}/hostfile "${HOST_NAME} slots=${N_CPU}\n")
   message( STATUS "hostfile written to: ${CMAKE_BINARY_DIR}/hostfile")