Change in build procedure

I’ve noticed that the latest build instructions have you create a build directory at the same level as the top-level root directory when cloning from the GitHub repository. When building 6.24 from the tar file, I have been creating the build directory as a sub-directory of the top-level root directory. In addition, I notice that the clone comes with a build directory already there. Not sure what purpose it serves.

Is there somewhere I can look that documents this change? I’m wondering if there are any other things I have to change from my old ways.

Please read tips for efficient and successful posting and posting code

ROOT Version: Not Provided
Platform: Not Provided
Compiler: Not Provided

ROOT build instructions have always been clear that CMake builds should be done outside of the source tree (note that also the old ROOT 5 has a “build” directory in its source tree).

Hi @marki , @Wile_E_Coyote ,
just to clarify, the build directory can be a sub-directory of the ROOT sources or it can be a sibling directory. What we mean when we say that in-source builds are not supported is that the build directory cannot be the same directory as the ROOT sources.

As @marki points out, the ROOT sources contain a directory called build already, so you have to use a different name for the build directory if you make it a sub-directory of the source directory. I usually use the name _build or cmake-build-debug, for example. In the future we would like to remove/rename the build directory so that the name is available for…well…actual build directories.

Also cmake -S root -B build && cmake --build build is effectively equivalent to mkdir build; cd build; cmake ../root; cmake --build ., but of course cleaner.

I hope this clarifies things a bit. Let us know if you think something in the build instructions at Building ROOT from source - ROOT should be clarified/improved.


Thanks all for the responses. That does clarify things for me.

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.