Dynamic linking error

[Titzi90]

Error at start up of external projects (like HPCG in miniapp rep.) after Cmake changes ( Pull request #1204):
error while loading shared libraries: libhpx.so.0: cannot open shared object file: No such file or directory

works fine if I manually add the path ("LD_LIBRARY_PATH=/path/to/hpx/installdir/lib/")
I think this path must be set in some CMake file.

At build time I use "-DHPX_DIR=/path/to/hpx/intalldir/lib/cmake/hpx" as described in the email from Thomas after his merge.

[sithhell]

This is a difficult issue to solve and I would like to discuss the different options we have here and start with an explanation how it worked before.
In the past, the FindHPX.cmake script used a manually computed rpath (from HPX_RPATH) to set a rpath for the compiled binaries. Whenever doing a hpx_add_executable (for example), the HPX cmake scripts added the necessary linker flags to set the rpath's to whatever was set in that CMake variable.

This approach worked to some extend but was neither elegant nor working consistently when people didn't use hpx_add_example. Or when installing binaries, the RPATH wouldn't get adapted correctly etc.

Fortunately, CMake comes with proper support to set the rpath for a compile executable (or not). You can see the documentation about it here: http://www.cmake.org/Wiki/CMake_RPATH_handling

In the latest changes i switched to conform to this behavior. What I find strange though is that CMake isn't setting the HPX path when linking an executable in the build dir ... but that is probably a cmake issue.

Now. In order to solve this issue you could either (every single option would require additional documentationt):

• Just set the LD_LIBRARY_PATH correctly
• OR: Use that one here in your external projects: http://www.cmake.org/Wiki/CMake_RPATH_handling#Always_full_RPATH

For the last option, this could be done, theoretically, by the HPXConfig.cmake script if some variable is set (for example if HPX_FULL_RPATH), or we can provide a cmake function which can be called by external projects to use this setting.

What would you like to happen?

[hkaiser]

I think requiring for the user to specify LD_LIBRARY_PATH is ok as it conforms to the use of other libraries.

[hkaiser]

Can we all agree on requiring to set LD_LIRARY_PATH (needs documentation!) and then close this ticket?

[sithhell]

Yes, or use what is recommended by the cmake documentation. Closing.

[hkaiser]

Do we have that documented?

[sithhell]

No. Reopening until docs are there.