Cppyy user-side breaks ROOT

[adriansev]

Explain what you would like to see improved

Installing a user-side cppyy (no virtualenv) breaks the python based ROOT tools.
So, i would like to be possible to have a user installed cppyy without this having an impact on ROOT installation

Optional: share how it could be improved

i was wondering if, given the special local only usage of a private/local version of cppyy, if this could be encapsulated somehow, so ROOT would use only it’s own version in such a way that is does not see any other cppyy version (even if discovered), and also the private cppyy modules are put in a place that would not be seen by anything outside ROOT as it’s not usable anyway:

[Thursday 06.04.23 21:38 adrian@hal] ~ $
python3
Python 3.11.2 (main, Feb  8 2023, 00:00:00) [GCC 12.2.1 20221121 (Red Hat 12.2.1-4)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cppyy
/usr/lib64/python3.11/site-packages/cppyy_backend/loader.py:90: UserWarning: No precompiled header available (/usr/lib64/python3.11/site-packages/cppyy_backend/etc not writable); this may impact performance.
  warnings.warn('No precompiled header available (%s); this may impact performance.' % msg)
/usr/lib64/python3.11/site-packages/cppyy/__init__.py:266: UserWarning: CPyCppyy API path not found (tried: /usr/include); set CPPYY_API_PATH to fix
  warnings.warn("CPyCppyy API path not found (tried: %s); set CPPYY_API_PATH to fix" % os.path.dirname(cpycppyy_path))

To Reproduce

rootls
usage: rootls [-h] [-1] [-l] [-t] FILE [FILE ...]
rootls: error: the following arguments are required: FILE

pip3 install --user cppyy

rootls
Traceback (most recent call last):
  File "/usr/bin/rootls", line 12, in <module>
    import cmdLineUtils
  File "/usr/share/root/cli/cmdLineUtils.py", line 81, in <module>
    import ROOT
  File "/usr/lib64/python3.11/site-packages/ROOT/__init__.py", line 25, in <module>
    cppyy.gbl.gROOT.SetBatch(False)
    ^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'TROOT' object has no attribute 'SetBatch'. Did you mean: 'GetPath'?

Setup

root-config --version
6.26/10

2. Fedora 37

3. dnf install

1st posted in root-forum: https://root-forum.cern.ch/t/cppyy-user-side-breaks-root/54393

[guitargeek]

Thanks for opening this issue! We need @vepadulano to take a look when he's back. On my side I can also recreate the crash on Arch Linux:

pacman -S root
pip install --user cppyy
python -c "import ROOT"