answered
2015-01-15 15:38:40 +0200
Short answer: There are no immediate plans to switch to a new major version.
Long answer: There is a lot of other work ongoing at the moment, and unfortunately, as a small company, not an infinite amount of resources to throw at things.
Upgrading something as crucial (and large) to the Sailfish platform takes a significant amount of time and effort. Sailfish exercises Qt (and QML/Quick) much more extensively than most Qt-based applications out there in the world. As a result, when running new code, we tend to run into a lot more bugs than most other users out there, and unlike regular Linux distributions, we need to fix as much of that as we possibly can so as to make sure that our customers have a smooth and painless experience with it.
This took a significant amount of time and effort for the 4.8 to 5.0 transition (before the product launch), and subsequent 5.2 transition, it's still not a fully complete effort in some ways. But it had significant benefits for Sailfish, so a commitment was made to do that. But engaging in the same effort again, so soon, would mean potential delays to other ongoing work, so although as a Qt advocate and developer I would want to push forward to the latest and greatest, I can't see it happening right now.
As for QtWebEngine: I've had the chance to use and explore it a bit myself over the past few months, and while I am impressed at the strides it has made in some directions (rendering quality and such), it is a largely unproven technology. It has never been used on Wayland at all in a product capacity (though I think some work has happened to enable it for 5.5 for that), and given our hardware constraints are fixed, we would also need to do some performance metrics and measurement to make sure that the device can capably handle it. The license would also need some consideration, as currently LGPLv3 is not permitted on device.
Again: due to the already large amount of ongoing work, I don't see that happening anytime soon.
Judging from this answer: we underestimated the work needed to successfully complete the Qt5.2 transition. It may take some time, 5.1 was released 18.06.2013 I dont think they will jump over 5.3 (May 2014), to go to 5.4 (release Dec 2014) things/code need time to mature when you are rolling it out to lots of users. NB: only a guess
emva ( 2015-01-13 16:38:20 +0200 )editOTOH the amount of changes between 5.0 and 5.2 has been much bigger than the difference between 5.2 and 5.4. Also there is quite a lot of stuff in 5.4 that Sailfish OS could benefit from, such as Qt Bluetooth with Bluetooth LE support or the already mentioned Qt Webengine.
MartinK ( 2015-01-13 16:48:54 +0200 )editThat answer also mentions "On a positive note, we have amended our integration process to avoid the pitfalls we faced during this transition. We have also enabled better ways to develop new features and technology in parallel with the main codebase, allowing integration only when code is relatively stable." so updating to newer Qt probably won't take as long as it did this time.
Btw you could also ask this question in the mailing list for developers: https://lists.sailfishos.org/cgi-bin/mailman/listinfo/devel
nthn ( 2015-01-13 18:24:11 +0200 )editJust a link: https://lists.sailfishos.org/pipermail/devel/2014-June/004595.html. Note the sentence: "For our Qt 5.2 branch, we still have a lot of patches, but all of these patches were upstreamed to 5.3 and 5.4 before they were back-ported into our 5.2 branch, ...". I'd think that Qt 5.4 support will come rather sooner than later, and it's not going to be the same kind of mess that happened with update 9.
Jouni Ahto ( 2015-01-13 20:36:47 +0200 )editI would guess that Qt5.4 could come by the time Sailfish 2.0 is out.
simosagi ( 2015-01-14 12:25:09 +0200 )edit