[doc] Building Doxygen documentation pollutes source directory

[ferdymercury]

Explain what you would like to see improved

To build the documentation using doxygen, one has to enter the (git) source directory and call Make. This creates some files in the source directory that are not part of the git tree.

Optional: share how it could be improved

I can think of two alternative options:

• The documentation can be created in the build directory rather than in the source directory
• A .gitignore file is created in documentation/ so that the are ignored when calling git status

To Reproduce

Build docu following https://root.cern/for_developers/doxygen/

Setup

   ------------------------------------------------------------------
  | Welcome to ROOT 6.25/01                        https://root.cern |
  | (c) 1995-2021, The ROOT Team; conception: R. Brun, F. Rademakers |
  | Built for linuxx8664gcc on May 17 2021, 10:49:42                 |
  | From heads/master@v6-25-01-861-g5ea261143f                       |
  | With                                                             |
  | Try '.help', '.demo', '.license', '.credits', '.quit'/'.q'       |
   ------------------------------------------------------------------

[ferdymercury]

Side note: calling make clean does not clean the directory in case the build failed. I get:

rm -r rootdoc filter htmlfooter.html dataset* ../../bindings/pyroot/pythonizations/python/ROOT/pythonization/*.pyzdoc
rm: cannot remove 'dataset*': No such file or directory
Makefile:56: recipe for target 'clean' failed
make: *** [clean] Error 1

[couet]

Yes that's known. We were lazy to fix that but we should.

[ferdymercury]

Here a good example on how ALICE's experiment generates the documentation directly in the build directory, using CMake:
https://github.com/AliceO2Group/Monitoring/blob/dev/doc/CMakeLists.txt#L22

[github-actions]

Hi @couet,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖