[ET Trac] [Einstein Toolkit] #1769: External libraries: moving towards multiarch library directory structure

[Einstein Toolkit]

#1769: External libraries: moving towards multiarch library directory structure
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  Reporter:  bmundim                |       Owner:                                  
      Type:  defect                 |      Status:  reopened                        
  Priority:  major                  |   Milestone:  ET_2016_05                      
 Component:  EinsteinToolkit thorn  |     Version:  development version             
Resolution:                         |    Keywords:  ExternalLibraries HDF5 Multiarch
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Changes (by knarf):

  * milestone:  ET_2015_11 => ET_2016_05


Comment:

 Replying to [comment:27 bmundim]:
 > the issue with using 'gcc --dumpmachine' is that we end up having a
 system directory in the middle of a list of directories in the linking
 stage. Then it could pick up other system libraries we might not want to
 use. As long as the system libraries are linked last then it should be ok.
 The same for the include directories. As long as the system include
 directories are last in the list then we are fine.

 This is not handled, true. We'll leave this for after the release now. The
 code stripping the paths would need to know about this (lib/sbin/strip-
 libdirs.sh) - and that code is not new, so that code wouldn't have
 stripped this in the old version as well.

 > Anyways, I am reopening this ticket because the script is not able to
 find /usr/include/hdf5.mod which is in my system and hdf5 library
 installed does support fortran.

 Assuming this is Ubuntu (trusty, and for reference):
 no pkg-config
 {{{
 /use/include/hdf5.h
 /usr/include/hdf5.mod
 /usr/lib/x86_64-linux-gnu/libhdf5.so
 }}}

 The script (on my Ubuntu VM) finds hdf5.h and libhdf5.so. It never checks
 for hdf5.mod (only for the relevant libraries). It does search for the
 include path, and finds it as /usr/include. Because that is a system
 include path, it does not get added to the INC_DIRS, for the reason you
 stated. It goes on marking the library as found and starts to compile. It
 never fails since there is no Fortran HDF5 code in the ET.

 Now, gfortran decided to not search standard include paths when looking
 for .mod files (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=35707). This
 means, to get things to compile, you would have to add -I/usr/include -
 which obviously is a bad idea in general. That's why distributions started
 to put these into separate directories, which is the only sensible way -
 but doesn't help us here now. We cannot add /usr/include in INC_DIRS in
 case Fortran is requested, because that might just break the next library.
 We also do not sort the list of library/include directories according to
 their 'is system path' status for each compiler command. We probably could
 dabble into that mess - but is that what you want?
 One possible easier way would be to detect such situation, and to copy the
 .mod file to somewhere inside Cactus, and reference that path. This would
 separate the mod file from the system include path. But this would require
 checking that this file is always up2date with it's original location. We
 could use a symlink to make sure this is true, but would still need to
 check for it dangling.

 In any case - I would like to see this issue with Fortran module files and
 standard include paths be rather in a new ticket, or things get too
 confusing here.

 > In addition your solution was applied only for HDF5 external library.
 There are others that need to be patched such as Boost, PAPI and pthreads.
 They were also moved to multiarch layout on ubuntu.

 Indeed. We didn't want to change all this for all libraries so short
 before a release. Eventually all libraries should use the flesh scripts.

-- 
Ticket URL: <https://trac.einsteintoolkit.org/ticket/1769#comment:28>
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