configuration - Getting CMake to build out of source without wrapping scripts

Question

I'm trying to get CMake to build into a directory 'build', as in project/build, where the CMakeLists.txt is in project/.

I know I can do:

mkdir build
cd build
cmake ../

but that is cumbersome. I could put it in a script and call it, but then it's unpleasant to provide different arguments to CMake (like -G "MSYS Makefiles"), or I would need to edit this file on each platform.

Preferably I would do something like SET(CMAKE_OUTPUT_DIR build) in the main CMakeLists.txt. Please tell me that this is possible, and if so, how? Or some other out of source build method that makes it easy to specify different arguments?

Answer 1

CMake 3.13 or newer supports the command line options -S and -B to specify source and binary directory, respectively.

cmake -S . -B build -G "MSYS Makefiles"

This will look for the CMakeLists.txt in the current folder and create a build folder (if it does not yet exist) in it.

For older versions of CMake, you can use the undocumented CMake options -H and -B to specify the source and binary directory upon invoking cmake:

cmake -H. -Bbuild -G "MSYS Makefiles"

Note that there must not be a space character between the option and the directory path.