[QGIS-Developer] cmake PYQT_SIP_DIR (via Python_SITEARCH) value wrong on Debian and derivatives

[Greg Troxel]

Richard Duivenvoorde via QGIS-Developer <qgis-developer at lists.osgeo.org>
writes:

> Hi Devs,
>
> I kept getting the https://github.com/qgis/QGIS/issues/54184 issue: sip not being able to find the Qt package sips: 'QtNetwork/QtNetworkmod.sip' could not be found etc etc

I have not tried to build anything beyond 3.34.3 so far.

> You can fix this with (on Ubuntu or Debian), by using (before your cmake step):
>
> export DEB_PYTHON_INSTALL_LAYOUT=deb
>
> Would it be possible/wise to add this to the standard QGIS build scripts?
>
> For more info/explanation, see https://github.com/qgis/QGIS/issues/54184#issuecomment-1935855984

How will this affect builds on other systems?   It seems there is
something deeper wrong, and the real problem might be that there are
multiple legitimate ways to install things, and that the Find script is
deficient.

How is it looking?   It would seem that finding the python directory
should use some python config mechanism.

On my system this file (3.28) is in

/usr/pkg/lib/python3.11/site-packages/PyQt5/bindings/QtNetwork/QtNetworkmod.sip

which seems like it follows the standard python approach (where choosing
a prefix other than /usr is within standard).

What are the variant places it is ending up in?

Shouldn't the Find script just look in both, if there are two normal
approaches?