[CMake] CMake finds wrong ar/ranlib/nm

[Auer, Jens]

Thanks a lot. Obviously, setting the environment when calling cmake is not enough. The command scl enable devtoolset-3 "cmake ../src"
sets the path etc and runs the cmake command, but it seems that cmake opens a new subshell with default settings. I've added the settings to .bashrc and it now finds the correct ar/ranlib etc.

Unfortunately,  this uncovered a bug in binutils on my system (centos 7) which results in a segfault when using ar to create a static lib with link-time-optimizations enabled. As a workaround, I tried to convert the library targets to OBJECT libraries, which also makes sense because I use the libraries to structure my project only. They are not delivered. However, this resulted in another problem with generator expressions. I will post another question for that.

Thanks,
  Jens

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-----Original Message-----
From: CMake [mailto:cmake-bounces at cmake.org] On Behalf Of Bill Hoffman
Sent: 28 July 2015 17:05
To: cmake at cmake.org
Subject: Re: [CMake] CMake finds wrong ar/ranlib/nm

On 7/28/2015 4:39 AM, Auer, Jens wrote:
> Hi,
>
> I am trying to use another compiler than the default one installed on 
> my system. I have to do this because I want to use a newer gcc than 
> the one on centos 7,so I installed RedHat Developer Toolset 3 with gcc 
> 4.9. When I call cmake with
>
> sclenable devtoolset-3 "cmake ../src" in my build directory, it 
> generates makefiles which use the new compiler and linker, but still 
> uses the default /usr/bin/ar etc. This is problematic because I enable 
> whole-program-optimization in release mode, and this needs to use the 
> ar provided with gcc 4.9 to handle the link-time optimization object files.
>
> I have tried various things to force cmake to use a specific ar, but 
> none of these worked:
>
> -Manually set CMAKE_AR in the CMakeLists.txt
>
> -Change CMAKE_AR in the cache
>
> -Write my own toolchain file
>
> With the toolchain file, cmake creates Makefiles but puts an empty ar 
> command in the lib "link" command, and building thus fails with an error.
>
> Am I missing something?
>
This is an environment thing.  Make sure the command line you are using is setup to find the other tools first in your PATH and it should work. 
  CMake assumes the environment is setup to work with the compiler you want to use.

-Bill

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