Improved CMake Find - Githubissues

swig-fortran / swig

This fork of SWIG creates Fortran wrapper code from C++ headers.

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Improved CMake Find #158

Closed mkstoyanov closed 4 years ago

mkstoyanov commented 4 years ago

Currently SWIG Fortran uses the SWIG_DIR variables but also requires manually setting SWIG_EXECUTABLE and the SWIG include dirs (if not set in the global environment). While spack does a pretty good job at adjusting the various environment variables, one possible use case is to install SWIG Fortran through spack and then use it from outside.

Proposed changes:

if SWIG_EXECUTABLE is not defined, search for swigfortran in ${SWIG_DIR}/bin/
add ${SWIG_DIR}/share/swig/4.0.2/ and ${SWIG_DIR}/share/swig/4.0.2/fortran/ to the include paths for the build interface of all swig targets
since currently the SWIG CMake module sets policies for CMake 3.14 (effectively requiring at least CMake 3.14), have the module accept SWIG_ROOT as an alternative to SWIG_DIR (as per newer CMake recommendations)

sethrj commented 4 years ago

@mkstoyanov Sorry I just now saw this issue, and I'm not sure I understand the problem that you're having.

You should only have to specify SWIG_EXECUTABLE; SWIG_DIR should automatically be set once the executable is found.
SWIG_DIR is not the "prefix" for swig; it's the root directory for the SWIG library .i files. It should have a different path from SWIG_ROOT.
FindSWIG is part of CMake, and the Fortran-enabled version I think you're using is an add-on file in Tasmanian which I copied from Flibcpp; and that has recently been updated (https://github.com/swig-fortran/flibcpp/pull/20) so I'd try updating your files to match that first.
SWIG should only be named swig or (on some systems) swigX.Y. Spack shouldn't be installing the binary name as swigfortran; does it?

mkstoyanov commented 4 years ago

SWIG_DIR is not needed, SWIG_EXECUTABLE is sufficient I tried to simply add SWIG_DIR and SWIG_ROOT to the root of the spack install (with the messy hash), but I see that I have to specify the executable.

For me, spack created a folder:

cd opt/spack/linux-<ubuntu-version>/gcc-8.3.0/swig-fortran-<hash>
ls -al bin/
     208696 Feb 24 14:51 ccache-swig
 22970704 Feb 24 14:51 swig
               4 Feb 24 14:51 swigfortran -> swig

So the swigfortran is a sym-link to swig, but it is there.

Also, for some strange reason, if I don't add include paths:

share/swig/4.0.2/
share/swig/4.0.2/fortran/

then I get some strange error about conflicting ierr, it goes away with those files ... but that may be some issue on my end.

I guess my main issue was that I could not find any documentation about the cmake options. You can close, if CMake is adding such documentation at the moment.