Cmake: Cross generate build systems from Linux possible? - cmake

Is it possible generate build systems on one platform for another using cmake? For example, and the case I'm most interested in, is it possible to generate a set of Visual Studio solution files, or mingw32-make Makefiles, or nmake files, for a project from Linux?
The intention is to make something analogous to what the make dist target produces in automake. However, I don't need it to do as much as make dist does, i.e. I just want to generate the solution files as though I'd run cmake in Windows.
Users can then build the package using the created build system on their own machines.
If it is possible, how do I do it? Cmake doesn’t report the Windows based generators as being available on Linux.

After further research I believe the answer to my question is no. The reason is that the makefiles and solution files etc. produced by cmake depend on cmake itself, the path to which is hard-coded into the files.
One solution for windows might be to bundle the cmake executable with your files and replace the definition of CMAKE_COMMAND (for instance) added to makefiles with the path to your bundled version of cmake somehow. This is just a suggestion though, I haven't tried or even researched it much. If you do, please post the process as a comment or answer here.

Related

Provide multiple toolchain options in CMake

I have an embedded project for ARM platform, specifically aarch64.
Up until now I was using Make. I recently set up CMake with no particular issues.
I moved to CMake because I was under the impression it was a more modern build tool that would have allowed a smarter configuration.
For example, I can compile my project using different toolchains (aarch64-elf-gcc-linaro, aarch64-linux-gnu-gcc,...) and I would like CMake to try if any of those are installed on the system and use whichever is found first by default.
Is this possible (or meant to)? I'd expect it to be an easy feat for the tool, but after searching for a while I can't seem to find the right track.
Yes, you can make your CMake project to search for available tool-chains installed in your OS, choose one and compile your project. I also write a CMake program for ARM embedded project, because now it is universal transferable between different OS system Windows and Unix. On Linux there is ARM ToolChain installed and on Windows there is Keil-MDK. If you have different tool-chains to choose between, you can write CMake script which will find paths with command like find_path() and then call correct "toolchianxx.cmake" script with right compiler flags for chosen compiler.
In your particular problem just use find_path commands and use hits to find installed compilers in "pre-set" known paths.

Cmake to generate solution file machine independent

I tried to generate a solution file of GSL library for visual studio 2012 using cmake gui. I did that successfully and I build the library for my own computer. But when I tried to build the same solution file in my different computer, it gives me errors saying "C:/my other computer directory/xxx.vcxproj does not exist" . Is there any way that I can generate sln file which is machine independent.
CMake is not designed to be used in this way, and it is highly unlikely you will be able to use it in this way. CMake performs system introspection, storing this in the CMake cache, and uses full paths to most things. I would advise you to run CMake on each system, and prefer offering simple instructions to run CMake/cmake-gui on each machine.

Can a library that uses CMake also be built with SCons?

I want to use KDL (Kinematics and Dynamics Library) in robot control box. But robot control box uses SCons as their build system while KDL uses CMake.
It turned out that the control box doesn't have CMake installed. Should I install CMake in the control box? Or write SCons file for compiling KDL?
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My question is ambiguous. Sorry for that. And unfortunately, I cannot show the link of Control Box, it's not public. Here is link of KDL installation manual.
http://www.orocos.org/kdl/installation-manual
Let me make it more clear.
Forget all of previous question above and all about Control box, KDL. Let's say that you want to use one library. But the library can be built using CMake according to installation manual. Your PC doesn't have CMake installed but it has SCons, and unfortunately you should not install CMake on your PC.
If you can only use SCons, what can you do?
I know this situation is not usual, I want to know your opinion.
To answer your initial question: Yes, you should always try to install CMake, if that is a build requirement for you library and if you need to build that library from the sources.
To answer your later question: Replacing or rewriting the build system scripts is a major effort and not advisable. In general there is no script to convert build-systems. Such script might help to make the manual transformation. If you have a look at LLVM's effort to replace Autotools by CMake or Boost replacing it's own build system by CMake, you find out it takes several people several years and still not everybody is satisfied.
Often you don't need to build the library yourself. Either there are already built packages from the project directly of from your distribution (Debian etc. packages) or third party packagers like Mac Ports or NuGet.
In your case KDL provides Debian/Ubuntu packages.
Additional KDL is part of ROS, which is experimental in Homebrew for OS X.

Is there a way for cmake to automatically extend the system PATH variable to compiled executables?

Can cmake configuration files also be used to automatically extend the system PATH variable to include the directory paths to all the installed executable applications and if it is possible (and a standard practice), how can I do this?
This way, as soon as I configure all the CMakeLists.txt files and everything compiles (and hopefully runs) nicely, I can start using the applications, and the path configuration would be packaged together with the build process. I am working with Linux and my code is written in C++, but since cmake is cross-platform, the question extends to other systems as well.
I'm unaware of any capability in CMake to do this. However, we based what we do what Cantera does. They upgraded to SCONS recently instead of their old build system, but the idea still applies.
Anyway, there's a script that CMake configures with the paths during the configure step and then installs somewhere. So once built on Linux, one would run make install then source ~/setup_cantera and it sets up all the variables needed.
We do the same thing for our libraries built with CMake. It's possible to detect which shell the user is running and configure an appropriate template script.

Do I really need cmake for build automation?

I'm currently investigating cmake to allow automatic building on the Win32 platform. For all runtimes and libraries I'd like to build, Visual Studio (2008/2010) projects do allready exist.
I've come across cmake, but I'm unsure if I really need it. As the documentation says, cmake generates VS projects and they then can be built e.g. using MSBuild.
As the projects itself allready do exist (and build nicely via the IDE or MSBuild on the cmd line), what do I need and use cmake for? Just for directory/project folder traversal? Build failure reporting?
Regards,
Paul
Well, strictly speaking you do not need it. However, it does give you a few advantages:
The idiomatic way to use CMake, forces you to use out-of-source builds. Arguable, but I am personally convinced that these keep you source-repository very clean.
You can support multiple visual studio versions (with the out-of-source builds). Perhaps it will be a little easier to port your project to other compilers (from MinGW -> Linux GCC).
With the find_package and config.cmake files, and a large number of available findXXX modules, CMake makes it a lot easier to "import" third-party libraries into your build-chain.
You don't need it. Cmake is only useful if you are trying to keep the same source code able to build in multiple platforms and compilers. If you are simply building using the microsoft stack you have no need of it.