[CMake] Dynamic library RPATH on OSX

[Steve Skutnik]

I'm having an issue with the RPATH not showing up for one of my shared
libraries on OSX. Basically, I end up with a "bare" rpath to one of my
shared libraries (i.e., no path prefix) when I check my binary using otool
- L

Specifically, I have a project with a structure that looks like this

project/module_A
project/module_B

I'm trying to build "Module B", which depends on a shared library I build
in "Module A". (I also use several other shared libraries, but all of them
are in system paths, i.e., /usr/local and /usr/lib.). What ends up
happening is that all of the rpaths are set *except* for my shared library
from Module A (for both the build and install versions of the binary).

After carefully reading the CMake primer on RPath handling here:

http://www.cmake.org/Wiki/CMake_RPATH_handling

I tried the suggestion under "Always full rpath", i.e., my CMakeLists.txt
file has the following:

# use, i.e. don't skip the full RPATH for the build tree
SET(CMAKE_SKIP_BUILD_RPATH  FALSE)

# when building, don't use the install RPATH already
# (but later on when installing)
SET(CMAKE_BUILD_WITH_INSTALL_RPATH FALSE)

SET(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")

# add the automatically determined parts of the RPATH
# which point to directories outside the build tree to the install RPATH
SET(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)


# the RPATH to be used when installing, but only if it's not a system directory
LIST(FIND CMAKE_PLATFORM_IMPLICIT_LINK_DIRECTORIES
"${CMAKE_INSTALL_PREFIX}/lib" isSystemDir)
IF("${isSystemDir}" STREQUAL "-1")
   SET(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")
ENDIF("${isSystemDir}" STREQUAL "-1")


However, this still doesn't appear to be setting the RPATH variable for my
dynamic library.  I likewise checked that CMAKE_INSTALL_RPATH is set
correctly (i.e., the library from Module A sits in that directory).
However, nothing I do seems to prefix an RPATH directory to my shared
library for Module A.

One other thing - I've also tried building this code on Linux
(Ubuntu-12.10), and I've noticed that the same configuration correctly sets
the RPATH for Module A - so this seems to be specific to OSX.

What am I missing here? Going through the list archives, I've seen this
problem pop up a few times with respect to OSX, but I haven't really seen
anything that specifically solves this issue. Specifically, this message
from a few weeks ago seems to be running into the exact same issue, but I
don't see any replies:

http://www.cmake.org/pipermail/cmake/2013-January/053335.html

The only other thread I've seen on this recently is here:

http://www.cmake.org/pipermail/cmake/2011-April/043888.html

The solution here was pretty much to either use install_name_tool manually
(which does work, but it requires one to do it each time you build) or to
use BundleUtilities. However, I noticed that CMake runs install_name_tool
on its own for a library which is built with Module B (i.e., I have
libModuleB_core.dylib which is built and linked into the moduleB binary);
i.e., this shows up in cmake_install.cmake. So shouldn't there be some way
to get CMake to appropriately run install_name_tool for me for Module A as
well? Or at the very least, is there a reason no RPATH is being appended to
Module A?

Thanks.

-Steve
---
Steve Skutnik, Ph.D.
http://neutroneconomy.blogspot.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.cmake.org/pipermail/cmake/attachments/20130213/0d839e01/attachment.htm>