using a keg-only dependency for a brew install cmake process

[ipatch]

i've been working on getting brew install freecad to an actual workable state, however one of the latest issues i'm running into is the cmake process that the brew install --verbose freecad kicks off does not manage to find the path / binaries for pyside@2.

freecad has several workbenches and runtime deps that require pyside@2 to be picked up durning the configure step of the installation. the cmake, make, make install processes will continue without knowning the path to the pyside@2 binaries required for runtime. however, after the install process completes on initial launch of freecad the $USER will be greeted with something like the below,

---

14:55:05  During initialization the error "No module named 'PySide2'" occurred in /Applications/freecads/brewmaster.brew.install/FreeCAD.app/Contents/Mod/Draft/InitGui.py
14:55:05  Please look into the log file for further information
14:55:07  During initialization the error "No module named 'PySide2'" occurred in /Applications/freecads/brewmaster.brew.install/FreeCAD.app/Contents/Mod/Arch/InitGui.py
14:55:07  Please look into the log file for further information
14:55:07  During initialization the error "No module named 'PySide2'" occurred in /Applications/freecads/brewmaster.brew.install/FreeCAD.app/Contents/Mod/AddonManager/InitGui.py
14:55:07  Please look into the log file for further information
14:55:07  During initialization the error "No module named 'PySide2'" occurred in /Applications/freecads/brewmaster.brew.install/FreeCAD.app/Contents/Mod/Tux/InitGui.py
14:55:07  Please look into the log file for further information
14:55:09  Unknown command 'Std_AddonMgr'
14:55:09  Traceback (most recent call last):
  File "<string>", line 2, in <module>
  File "/Applications/freecads/brewmaster.brew.install/FreeCAD.app/Contents/Mod/Start/StartPage/StartPage.py", line 29, in <module>
    from . import TranslationTexts
  File "/Applications/freecads/brewmaster.brew.install/FreeCAD.app/Contents/Mod/Start/StartPage/TranslationTexts.py", line 24, in <module>
    from PySide import QtGui
  File "/Applications/freecads/brewmaster.brew.install/FreeCAD.app/Contents/MacOS/PySide/__init__.py", line 2, in <module>
    from PySide2 import __version__
<class 'ModuleNotFoundError'>: No module named 'PySide2'
14:55:09  No module named 'PySide2'

---

in contrast, if i run brew link pyside@2 before running brew install freecad then the cmake process will pickup/detect pyside@2 binaries required for bundling into the FreeCAD.app bundle during the make install process of the brew install freecad command/process.

...that's good to know but doesn't seem to help when requiring pyside@2 to be linked using github actions.

please correct if i'm wrong, but since pyside@2 is keg-only brew test-bot will not link pysdie@2 during the steps of building freecad.

i attemtped adding the .bin prefix path with the following line in the freecad.rb formula, and the reran brew install freecad but cmake still did not detect the pyside@2 installation / path to required runtime binaries to bundle into the FreeCAD.app bundle.

ENV.prepend_path "PATH", Formula["pyside@2"].bin

i've read the formula cookbook several times, but haven't come across a use case in there that could help me resolve this issue that is arising.

as always, any and all help would be greatly appreciated 🙏

[carlocab]

It's a bit weird the CMake doesn't find pyside@2 during the build, since usually CMake is pretty good at finding keg-only dependencies.

Try doing

ENV.prepend "CMAKE_PREFIX_PATH", Formula["pyside@2"].opt_lib/"cmake"

in the formula. If that doesn't help (it might not, since this path should already be in CMAKE_PREFIX_PATH), then it might help to manually set PYSIDE2UICBINARY and PYSIDE2RCCBINARY by passing them with -DPYSIDE2UICBINARY=foo in your cmake invocation.

Finally, failing that, it seems like it's just a matter of finding Python modules, so it might work to just find a way to expose the environment variable PYTHONPATH="$(brew --prefix pyside@2)/lib/python3.9/site-packages" to your freecad binary at runtime.