566309 - [pushes] reverse diff should be prohibited

Status: RESOLVED WONTFIX

(Webtools Graveyard :: Elmo, defect, P5)

Description

[Tomer Cohen :tomer]

Attachment: Regular behavior (screenshot)

When watching the push logs, you can diff from one revision to another, making in possible to diff one revision as 'diff from' to an older revision as 'to'. This make the diff function to behave incorrectly and show removed files/strings as added and vice versa. 

Here is a diff I made for a revision where I've removed some files from - https://l10n-stage-sj.mozilla.org/shipping/diff?from=938ff323de04&to=82638ca2241f&repo=releases%2Fl10n-mozilla-1.9.2%2Fhe
And here is the negative diff which show the same files as being added - https://l10n-stage-sj.mozilla.org/shipping/diff?from=82638ca2241f&to=938ff323de04&repo=releases%2Fl10n-mozilla-1.9.2%2Fhe

(I've used the releases/l10n-mozilla-1.9.2/he repo - https://l10n-stage-sj.mozilla.org/pushes/?repo=releases/l10n-mozilla-1.9.2/he)


Expected solution(s):
I can think about two different ways to solve this, both require just few changes to the pushlog ui - 
a. When user try to trigger negative diff, warn him or just do the expected behavior by switching between the two revision parameters. 
b. Like other revision comparing functions (mediawiki, wordpress etc.) - hide the diff buttons for revisions past the selected one. (See edited screenshot)

Comment 1

[Tomer Cohen :tomer]

Attachment: wrong behavior (negative diff)

Comment 2

[Tomer Cohen :tomer]

Attachment: suggested solution

Comment 3

[Axel Hecht [:Pike]]

The other alternative would be to allow the diff, but to reorder them to be in forward direction when shown.

Comment 4

[Staś Małolepszy :stas]

I like comment 3.

Comment 5

[Axel Hecht [:Pike]]

I think that reverse diffs should be allowed, but warned about.

Note, this is really about TO being an ancestor of FROM. If you're going off of linear history, things become less obvious. We could also warn if the FROM is newer than the TO.

I don't really think this is a P3, though, retriaging to P5.

Comment 6

[BMO Automation]

The production instance of Elmo running on l10n.mozilla.org has been decommissioned as of September 2020, and there are no plans to develop this project further.