Python interpreter starts hardwired to search buildSourcePath when run from build directory

[qgib]

Author Name: Larry Shaffer (Larry Shaffer)
Original Redmine Issue: 6913
Affected QGIS version: master
Redmine category:python_plugins

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A current issue regarding the loading of plugins (while running from the build directory) is when plugins are restored on launch of the app. There is currently a goofy fix for this with commits e31fb3c and where QgsApplication::pkgDataPath() is temporarily set to something other than QgsApplication::buildSourcePath() when restoring core plugins.

The reason for that patch: when QgsPluginRegistry::restoreSessionPlugins() is called the Python packages are imported from QgsApplication::buildSourcePath()/python/plugins even though that path is NOT in sys.path for the interpreter. If QgsApplication::pkgDataPath() is pointed to something other than QgsApplication::buildSourcePath(), or an empty QString, it works. However, I could find no means by which the interpreter was assigned that module search path.

I have tried:

• changing the current working directory in C++ and via Python
• setting PYTHONPATH
• setting all kinds of debug output from the interpreter (never shows buildSourcePath()/python/plugins in sys.path)
• giving up <-- that kinda worked

To reproduce the issue, run QGIS from the build directory and then launch DB Manager core plugin. You will get an error about a missing ui_*.py file, because that 'compiled' version of a *.ui file does not exist in source directory, only in the @build/output/python/plugins@ staged version of the plugin.

Now, run QGIS again, but with the @--noplugins@ option. This will keep @restoreSessionPlugins()@ from being called. After using Plugin Manager to turn back on DB Manager, launch the plugin and you should not get the error: sys.path is being honored, and the plugin is imported from @build/output/python/plugins@ staged area, as expected.

While the current patch works, it requires core plugins to not request QgsApplication::pkgDataPath() when the plugin loads. A better solution is needed.

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Related issue(s): #15338 (relates)
Redmine related issue(s): 5879

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[qgib]

Author Name: Giovanni Manghi (@gioman)

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• easy_fix was configured as 0
• regression was configured as 0

[qgib]

Author Name: Giovanni Manghi (@gioman)

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End of life notice: QGIS 2.18 LTR
*
Source:*
http://blog.qgis.org/2019/03/09/end-of-life-notice-qgis-2-18-ltr/

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• resolution was changed from to end of life
• status_id was changed from Open to Closed