warning, install problems seems to be fixed but running

$ spack spec libsplash ^[email protected]

Input spec
------------------------------
  libsplash
      ^[email protected]

Normalized
------------------------------
==> Error: libsplash does not depend on hdf5

still complains.

Read through all comments and commits in #1553. That should explain what is causing the problem and a decent solution to it. My solution isn't perfect, but I think it provides the least headaches.

all right, will wait on the decision there. a hdf5+mpi default might auto-fix it for me.

the normalization process still looks a bit uneasy to me if we have to introduce conventions like "all need to default to +mpi" to get around it. (independent of the fact that I like an all +mpi default, but this won't be the only dependency triggering such issues.)

I agree. At some point we need to tackle variant forwarding. That is, if I specify netcdf+mpi, that means I want the mpi variant to be enabled for netcdf and all of its dependencies, not just netcdf. But for now, this is the best we can do.

Kind of. But I can also think of software that can be compiled with a +mpi variant but that will only depend on serial hdf5 for posix style i/o (would still compile successfully against hdf5+mpi but does not require it).

the point is: if a dependency hdf5+mpi is set in a package, this should be honoured. And then again the exact dependencies that a build of hdf5+mpi triggers.

we should not rely on that +mpi means the same on all packages.

@adamjstewart since #1553 is now merged I removed the first commit locally and tried again.

Interestingly, running spack spec is still weird, see this output: (in libSplash +mpi is also the default):

# with defaults: fails
$ spack spec libsplash
Input spec
------------------------------
  libsplash

Normalized
------------------------------
  libsplash
      ^cmake
      ^[email protected]:
          ^zlib

Concretized
------------------------------
==> Error: Invalid spec: '[email protected]%[email protected]+cxx~debug+fortran~mpi+shared~szip~threadsafe arch=linux-debian8-x86_64'. Package hdf5 requires variant +mpi, but spec asked for ~mpi

# with explicit +mpi: ok
$ spack spec libsplash+mpi
Input spec
------------------------------
  libsplash+mpi

Normalized
------------------------------
  libsplash+mpi
      ^cmake
      ^[email protected]:+mpi
          ^mpi
          ^zlib

Concretized
------------------------------
  [email protected]%[email protected]+mpi [...]

# with explicit ~mpi: ok
$ spack spec libsplash~mpi                                                                                                                      (topic-updateSplashPngDev $<>)
Input spec
------------------------------
  libsplash~mpi

Normalized
------------------------------
  libsplash~mpi
      ^cmake
      ^[email protected]:
          ^zlib

Concretized
------------------------------
  [email protected]%[email protected]~mpi [...]

ah no I am wrong, I rebased against my local branch and not the remote one. seems to work now!

will open a new PR with the develop versions.