What are the dusty corners a newcomer to CMake will want to know?

Question

I\'ve done a lot of projects and a lot of different build systems and CI tools. Most recently, I\'ve been exposed to the occasionally challenging task of adding to an autot

Answer 1

First of all, I think CMake is an excellent build-tool. It has in my opinion by far the best support for multi-platform-builds and has a powerful mechanism for finding 3rd-party libraries. Combined with CPack it even provides reasonable options for packaging and installation. Some hints and possible problems:

1. Always aim for out-of-source builds: An obvious one: It can be difficult for a project designed for in-source builds to get it built out-of-source. So, if you can design it from the start, aim for out-of-source builds.

2. Syntax: The syntax can be bizarre with a lot of strange quirks, although this is getting better since the 2.6 and 2.8 versions.

3. Caching of variables. CMake keeps track of a cache of variables and settings and sometimes this can be a problem when rebuilding something. Try to remove the CMakeCache.txt (or clean your out-of-source build-directory) and rebuild. This one is also mentioned by DarenW.

4. Finding and configuring 3rd-party libraries: If you have a large project depending on several libraries (your own or 3rd-party), this will likely be the most troublesome.

   • I seriously recommend diving into the find_package command. It is very powerful, but fully depends on the quality of the FindXXX.cmake files. Especially when building on multiple platforms (mostly Windows and Mac), these files may require some tweaking or you may need to write your own.

   • Problems with linking libraries like debugging "undefined references" or mismatches between debug|release or static|shared can be difficult to debug. Especially with 3rd-party libraries these problems may be caused by incorrect 3rd-party FindXXX.cmake files...