[lldb-dev] Heads-up: FreeBSD LLDB CMake build broken by relative rpath change

[Brad King]

On 02/27/2014 07:49 AM, Rafael Espíndola wrote:
> On 26 February 2014 21:40, Ed Maste <emaste at freebsd.org> wrote:
>> This at least has a straightforward explanation -- for the configure
>> build my binary ends up with an rpath containing both the
>> $ORIGIN-based relative path as well as an absolute path:
>>
>> feynman% readelf -d ./Debug+Asserts/bin/lldb | grep PATH
>>  0x000000000000000f (RPATH)              Library rpath:
>> [$ORIGIN/../lib:/tank/emaste/src/llvm/build-make/Debug+Asserts/lib]
>>  0x000000000000001d (RUNPATH)            Library runpath:
>> [$ORIGIN/../lib:/tank/emaste/src/llvm/build-make/Debug+Asserts/lib]
> 
> Brad, is there a way to add to rpath from an inner CMakeLists.txt?

The CMAKE_INSTALL_RPATH variable is not actually a global setting
but is rather used to initialize the INSTALL_RPATH target property:

 http://www.cmake.org/cmake/help/v2.8.12/cmake.html#prop_tgt:INSTALL_RPATH

on each library or executable target as it is created.  One may
append to an individual target's INSTALL_RPATH property or may
set CMAKE_INSTALL_RPATH in the current directory scope to influence
targets in the directory and below.

IIUC the reason LLVM can use BUILD_WITH_INSTALL_RPATH is because
it is careful to lay out the build tree binaries the same way as
they appear in the install tree so $ORIGIN/../lib works in both
places.  If LLDB is building externally then its binaries will not
appear in the right relative location to use that RPATH.  It could
consider using INSTALL_RPATH_USE_LINK_PATH:

 http://www.cmake.org/cmake/help/v2.8.12/cmake.html#prop_tgt:INSTALL_RPATH_USE_LINK_PATH

so that LLDB binaries are built and installed with the RPATH pointing
at locations used at link time to search for external libraries.

Alternatively it could not use BUILD_WITH_INSTALL_RPATH and instead
allow CMake to handle the build-tree RPATH as it likely did before
this change.

-Brad