fujitsu-mpi package: help CMake find wrappers (#43979)

Set MPI_C_COMPILER etc. env vars when building with fujitsu-mpi, which
override CMake logic. Without using these variables to explicitly
request the Fujitsu MPI wrappers, the builtin CMake logic is unwilling
to use these wrappers unless the Fujitsu compiler is used, but they
should be used for %clang as well.

This avoids patching CMake module files like in #16864, primarily to
avoid the possibility of altering behavior for specs that do not use
%fj or ^fujitsu-mpi.

1 files changed, 10 insertions, 0 deletions

diff --git a/var/spack/repos/builtin/packages/fujitsu-mpi/package.py b/var/spack/repos/builtin/packages/fujitsu-mpi/package.py
index 91ba765750..475cec6ce7 100644
--- a/var/spack/repos/builtin/packages/fujitsu-mpi/package.py
+++ b/var/spack/repos/builtin/packages/fujitsu-mpi/package.py
@@ -53,6 +53,16 @@ class FujitsuMpi(Package):
             self.spec.mpif77 = self.prefix.bin.mpifrt
             self.spec.mpifc = self.prefix.bin.mpifrt
 
+    def setup_dependent_build_environment(self, env, dependent_spec):
+        if self.spec.satisfies("%gcc"):
+            env.set("MPI_C_COMPILER", self.prefix.bin.mpicc)
+            env.set("MPI_CXX_COMPILER", self.prefix.bin.mpicxx)
+            env.set("MPI_Fortran_COMPILER", self.prefix.bin.mpifort)
+        else:
+            env.set("MPI_C_COMPILER", self.prefix.bin.mpifcc)
+            env.set("MPI_CXX_COMPILER", self.prefix.bin.mpiFCC)
+            env.set("MPI_Fortran_COMPILER", self.prefix.bin.mpifrt)
+
     def setup_run_environment(self, env):
         # Because MPI are both compilers and runtimes, we set up the compilers
         # as part of run environment