[CMake] policy CMP0003 and full path, but still conflict with implicit directories

[Bill Hoffman]

PG wrote:
> 
> Hi all,
> 
> I want to link a target to libraries A and B.
> A is in the /usr/lib directory, and B is in another directory, say 
> /some/path. My problem is that an old version of A also exists in the 
> directory /some/path, and if I add this directory to the linker search 
> path, /some/path/A will be found instead of /usr/lib/A.
> 
> I am using cmake 2.8 on linux (ubuntu 9.10 karmic), and found that with 
> policy CMP0003, libraries with full path provided shouldn't produce 
> linker search paths entry.
> I made sure this policy is active by adding a
>   CMAKE_POLICY(SET CMP0003 NEW)
> even though I used
>   CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
> at the beginning of my CMakeList.txt file.
> 
> I add these to library to the linker using full path:
>   TARGET_LINK_LIBRARY(target /usr/lib/A /some/path/B)
> 
> I run cmake and got the error:
> 
> CMake Warning at CMakeLists.txt:67 (add_executable):
>   Cannot generate a safe linker search path for target target because files
>   in some directories may conflict with libraries in implicit directories:
> 
>     link library [A] in /usr/lib may be hidden by files in:
>       /some/path
> 
>   Some of these libraries may not be found correctly.
> 
> 
> I checked the file CMakeFiles/target.dir/link.txt
> and get a line like
>   /usr/bin/c++ [...] -L/some/path -lA -lB
> where I would like to see
>   /usr/bin/c++ [...] -lA /some/path/B
> according to what I understood from the CMP0003 policy help page.
> This:
>   /usr/bin/c++ [...] -lA -L/some/path/ -lB
> would also work, but as far as I understand this is not what policy 
> CMP0003 should produce.
> 
> 
> I googled for a solution, but cannot find any that corresponds to my 
> case. I still don't understand why I get the "-L" statement while using 
> policy CMP0003.
> 
> I also tried adding a
>   LINK_DIRECTORIES(/usr/include)
> to get at least something like
>   /usr/bin/c++ [...] -L/usr/lib,/some/path -lA -lB
> so /usr/lib/A will be found prior to /some/path/A, but it didn't change 
> anything. I guess it is because /usr/lib is an implicit directory.
> 
> 
> Is there a way to have this working, knowing that B is from a third 
> party software, meaning that I don't have control on what files are 
> present or not in the /some/path directory?
> I can of course manually edit the CMakeFiles/target.dir/link.txt file 
> after running cmake, but as my code is to be installed by some users on 
> their own computer, I would like to avoid asking them to do this.
> 

Can you create a small example that shows the problem you are having?

Also, you might want to run cmake --trace and make sure nothing is 
changing the policy on you...

-Bill