corrupted QML cache for messaging app makes it crash at startup

[Olivier Tilloy]

This is on krillin image #95 from the 14.09-proposed channel.

How I got there:

 - sent an MMS with a vodafone SIM card
 - switched off the phone, removed the SIM, inserted a movistar SIM in place, switched the phone back on
 - unlocked the SIM by entering pin, tapped on the messaging app icon

At this point the messaging app failed to start, it crashed reliably at startup. Removing the QML cache under ~/.cache/QML/Apps/messaging-app/ solved the issue. I’m attaching an archive containing the corrupted cache.

ProblemType: Bug
DistroRelease: Ubuntu RTM 14.09
Package: libqt5qml5 5.3.0-3ubuntu13~test1
Uname: Linux 3.4.67 armv7l
ApportVersion: 2.14.7-0ubuntu5
Architecture: armhf
Date: Fri Oct 10 17:45:59 2014
InstallationDate: Installed on 2014-10-10 (0 days ago)
InstallationMedia: Ubuntu Utopic Unicorn (development branch) - armhf (20141010-030205)
SourcePackage: qtdeclarative-opensource-src
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Ricardo Mendoza (ricmm)]

The issue at hand is a wrong assumption done by the cache loader that if the changes to the source files are minimal, a single recompile of the changed files is enough. This has proven to be not true, instead, a full recompilation needs to happen as the QML meta tree might have changed in ways that could cause weird application behaviour, or outright crashes.

The solution is:

1. Invalidate the full cache if any of the source files has been changed, and recompile in full.
2. If an application crashes during startup, wipe its cache to increase stability.