[CMake] LOCATION target property, generator expressions

[Hendrik Sattler]

Hi,

You can use the following cmake snippet right below the project()  
command to add proper RPATH values:
   include ( GNUInstallDirs )
   if ( CMAKE_SYSTEM_NAME STREQUAL "Linux" )
     list ( APPEND CMAKE_INSTALL_RPATH "\$ORIGIN/../${CMAKE_INSTALL_LIBDIR}" )
   endif ( CMAKE_SYSTEM_NAME STREQUAL "Linux" )
   set ( CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE )

This assumes, libraries are installed to CMAKE_INSTALL_LIBDIR and  
programs to CMAKE_INSTALL_BINDIR.
Additionally you may add the following line to disable a change in the  
binary files during install target run:
   set ( CMAKE_BUILD_WITH_INSTALL_RPATH ON )


The latter might be useful when splitting of debug symbols on ELF  
platforms in post-build. However, it disables running the binaries in  
the build tree.


CMake supports PDB files but split dbgsym file are (strangely) not  
supported out-of-the-box.

HS


Zitat von Hendrik Greving <hendrik.greving.smi at gmail.com>:

> By the way, the new generator expression support in 3.13, is this for
> LINK_FLAGS or LINK_OPTIONS. And regardless of the former, will it be
> possible to compute a relative path based on generator expressions, i.e.
> file(RELATIVE $<TARGET_FILE_DIR:mytarget> $<TARGET_FILE_DIR:mytargetlib>)?
>
> On Thu, Sep 27, 2018 at 5:03 PM Hendrik Greving <
> hendrik.greving.smi at gmail.com> wrote:
>
>> Thanks. Ok one step back. What we want is to have the same relative path
>> from binary/executable to linked library in build and install tree (which
>> we assume is the same for us). Looks like by default, e.g. cmake 3.9, puts
>> in an absolute path. The current (c-)makefiles compute the relative part of
>> an executable -> library by using LOCATION and add this to
>> -Wl,-rpath=$ORIGIN/[relative part]. We want to do the same w/o LOCATION
>> (i.e. resolving CMP0026)
>>
>> On Thu, Sep 27, 2018 at 7:29 AM Brad King <brad.king at kitware.com> wrote:
>>
>>> On 09/26/2018 10:23 AM, Hendrik Greving wrote:
>>> > Is there any way before 3.13 to achieve what I need? Right now we
>>> > modify LINK_FLAGS based on something that is computed with values
>>> > from LOCATION.
>>> [snip]
>>> > our cmake setup is using LOCATION property for two targets to compute
>>> > a relative path from these two, and adds this to LINK_FLAGS
>>> > (for rpath, but irrelevant in this context).
>>>
>>> To at least see if 3.13 will support your use case, you could
>>> try a nightly binary from here:
>>>
>>>   https://cmake.org/files/dev/?C=M;O=D
>>>
>>> Use `$<TARGET_FILE_DIR:mytarget>/..` to refer to a path relative
>>> to the target file location.
>>>
>>> I've never seen a need to adjust link flags based on the target
>>> location.  CMake has several features for RPATH support.  What
>>> are you really trying to do?
>>>
>>> -Brad
>>>
>>