WIP: Use findMPI earlier.

Author: vehre

CMakeLists.txt

@@ -282,7 +282,9 @@ if (C_COMPILER_NAME MATCHES "^[mM][pP][iI]")
   set (MPI_C_COMPILER "${CMAKE_C_COMPILER}")
 endif()
 
-if(WIN32) # Only support building with GCC & GFortran using Intel MPI (OneAPI)
+find_package(MPI)
+
+if(WIN32 AND NOT MPI_FOUND) # Only support building with GCC & GFortran using Intel MPI (OneAPI)
   # Here we assume Intel ONEAPI and the environment is loaded
   set( MPI_ASSUME_NO_BUILTIN_MPI TRUE )
   set( MPI_CXX_SKIP_MPICXX TRUE )
@@ -319,7 +321,6 @@ if(WIN32) # Only support building with GCC & GFortran using Intel MPI (OneAPI)
   set(MPI_Fortran_HAVE_F08_MODULE FALSE)
 
 endif()
-find_package( MPI )
 
 if ( (NOT MPI_C_FOUND) OR (NOT MPI_Fortran_FOUND) OR (NOT MPIEXEC_EXECUTABLE))
   # Get default install location of MPICH from install.sh
@@ -339,7 +340,7 @@ MPIEXEC_EXECUTABLE = ${MPIEXEC_EXECUTABLE}
     HINTS "${FTN_COMPILER_DIR}" "${C_COMPILER_DIR}"
     PATH_SUFFIXES bin)
   set ( MPI_HOME "${MPI_HOME}" "${MY_MPI_EXEC}" "${MY_MPI_EXEC}/.." )
-  find_package( MPI REQUIRED )
+#  find_package( MPI REQUIRED )
 endif()
 list(REMOVE_DUPLICATES MPI_Fortran_INCLUDE_DIRS)