On 2017-03-07 8:02 PM, Ben Kelly wrote: > On Tue, Mar 7, 2017 at 6:09 PM, Xidorn Quan <m...@upsuper.org> wrote: > >>> This major version change is downgrade-incompatible, so IndexedDB and >>> DOM cache won't work in an older version if their profile has been >>> upgraded. >>> IndexedDB is also used internally, so stuff that depends on it likely >>> won't work too. >>> There's bug 1246615 [2] where you can find a discussion related to this >>> issue. >> >> It would probably be a good idea to backup the old files when upgrading, >> so that old version can at least pick the backup file to use. >> > > Maintaining downgrade compatibility is a lot more complex than people think
Yes. > and we have zero test support for it. This part isn't entirely true. The full picture is a bit more complex. Some components have supported full downgrades with automated tests running on the infrastructure for years. Examples are the cookie manager and the permission manager. Other components have intentionally decided that it's OK to not maintain backwards compatibility, for example, IndexedDB. In other places, people (myself included) have just not been careful enough and have (either intentionally or unintentionally) landed code that isn't downgrade compatible. It's certainly true that in general there is no tests that would catch you if you land code that breaks a downgrade scenario, and over the years it has become quite clear that maintaining a downgrade-compatible browser is impractical. I agree with Ben, Jan and others that this situation is unsustainable, and we have to do something about it. I also agree with Xidorn about how bad it is that we risk destroying data from the very subset of our user population who go out of their way to help us by testing changes on newer builds and risk losing their data when going back to an older build. To be perfectly honest, the situation in bug 1246615 is quite frustrating. I no longer understand what we are waiting for in that bug. It seems like that bug is being scope creeped into a larger plan (based on comment 29 there) and still unclear what that exactly means, and here we are now: while Firefox 55 rides the trains, we *will* destroy our community's browsing data as they help us test Firefox. Benjamin, can we please address this with the urgency it deserves? Thank you for your attention. Cheers, Ehsan _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
