Workaround until variant forwarding works properly

var/spack/repos/builtin/packages/hdf5/package.py

@@ -52,7 +52,7 @@ class Hdf5(Package):
     variant('cxx', default=True, description='Enable C++ support')
     variant('fortran', default=True, description='Enable Fortran support')
 
-    variant('mpi', default=False, description='Enable MPI support')
+    variant('mpi', default=True, description='Enable MPI support')
     variant('szip', default=False, description='Enable szip support')
     variant('threadsafe', default=False,
             description='Enable thread-safe capabilities')

var/spack/repos/builtin/packages/netcdf/package.py

@@ -52,15 +52,16 @@ class Netcdf(Package):
     depends_on("zlib")
     depends_on('hdf5')
 
-    # Variant forwarding
-    depends_on('hdf5+mpi',  when='+mpi')
-    depends_on('hdf5~mpi',  when='~mpi')
-
     # NetCDF 4.4.0 and prior have compatibility issues with HDF5 1.10 and later
     # https://github.com/Unidata/netcdf-c/issues/250
     depends_on('hdf5@:1.8', when='@:4.4.0')
 
     def install(self, spec, prefix):
+        # Workaround until variant forwarding works properly
+        if '+mpi' in spec and spec.satisfies('^hdf5~mpi'):
+            raise RuntimeError('Invalid spec. Package netcdf requires '
+                               'hdf5+mpi, but spec asked for hdf5~mpi.')
+
         # Environment variables
         CPPFLAGS = []
         LDFLAGS  = []