Reserve "build" directory name in ROOT sources for build files

[eguiraud]

Explain what you would like to see improved

This would make it possible to use build as a build directory name under the source directory. Having a build directory under the source directory is common practice: several code editors do it by default, and it helps tools like ccache recognize when the same software is built multiple times (see ccache's base_dir feature).

There is a precedent in roottest in reserving build in .gitignore, and some C++ project layout guidelines such as pitchfork suggest the usage of build as a reserved, preferred name for build directories. Other precedents are entries such as cmake-build and .build in ROOT's .gitignore, with the exact same rationale, because those are the build directory names that CLion and VSCode pick.

Our current build directory should therefore be renamed and build should be added to our .gitignore.

An alternative considered was _build, but Axel suggested to use the more proper build, at the cost of renaming the already existing directory: see https://github.com/root-project/root/pull/8009 .

[eguiraud]

Hi, little ping on this, it would be a big quality of life improvement for me :)

[guitargeek]

This is a very low-hanging fruit, no? The directory build is not so populated anyway:

build
├── CMakeLists.txt
├── gdbPrinters
│   ├── libCore.so-gdb.py
│   └── libRooFitCore.so-gdb.py
├── misc
│   └── argparse2help.py
├── rmkdepend
│   ├── cppsetup.c
│   ├── def.h
│   ├── ifparser.c
│   ├── ifparser.h
│   ├── imakemdep.h
│   ├── include.c
│   ├── main.c
│   ├── mainroot.cxx
│   ├── parse.c
│   └── pr.c
├── unix
│   ├── check_dups_in_pcms.py
│   ├── compiledata.sh
│   ├── makedistsrc.sh
│   ├── makepchinput.py
│   ├── makereleasenotes.sh
│   ├── module.modulemap
│   ├── pandoc-jira.sh
│   └── rootmapcat.py
└── win
    ├── bindexplib
    │   └── bindexplib.cxx
    ├── cl.sh
    ├── f77.sh
    ├── ld.sh
    ├── makelib.sh
    ├── makeresource.sh
    ├── sehmap.h
    └── w32pragma.h

7 directories, 30 files

Alternative name suggestions:

• buildtools
• tools
• misc
• _build
• utils
• buildutils

Personally I would go for utils, because it mimics also a bit what LLVM does (see interpreter/llvm-project/llvm/utils).

[guitargeek]

I would really like if we can do something about this, as also nixpkgs uses by default the build directory in the sources for building :slightly_smiling_face:

Does anyone have feedback on my suggestion?

[pcanal]

We also already have a misc directory. The content of build is a mix of things that would belong there and things that are using during the build (and things that are seemingly not used (argparse2help?)).

So the content could also be dispersed between misc and cmake

[pcanal]

Following #16245, most of the build directory was moved out. Some are still left (looks like mostly items that could move to cmake directory)

[guitargeek]

@pcanal, thanks for re-opening, GitHub automatically closed it because of the associated PR!

This is the list of files that is still left:

build
├── CMakeLists.txt
├── unix
│   ├── check_dups_in_pcms.py
│   ├── compiledata.sh
│   ├── makedistsrc.sh
│   ├── makepchinput.py
│   ├── makereleasenotes.sh
│   ├── module.modulemap
│   ├── pandoc-jira.sh
│   └── rootmapcat.py
└── win
    ├── bindexplib
    │   └── bindexplib.cxx
    ├── cl.sh
    ├── f77.sh
    ├── ld.sh
    ├── makelib.sh
    ├── makeresource.sh
    ├── sehmap.h
    └── w32pragma.h

4 directories, 17 files

[guitargeek]

What is left now:

build
└── unix
    ├── check_dups_in_pcms.py
    ├── compiledata.sh
    ├── makedistsrc.sh
    ├── makepchinput.py
    ├── makereleasenotes.sh
    ├── module.modulemap
    ├── pandoc-jira.sh
    └── rootmapcat.py

2 directories, 8 files