2072095 - Make `nsRange::CharacterDataChanged` stop droing wrong handling at split text

Status: RESOLVED FIXED

(Core :: DOM: Selection, defect)

Description

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)(PTO: 9/19-9/27)]

AI review pointed an extant bug of nsRange::CharacterDataChanged:
https://phabricator.services.mozilla.com/D323941#inline-1733034

The comment on line 630 says "register the range to the new common ancestor", but when only the end boundary moves to the new sibling (start stays on the original node), the registered node is not the actual common ancestor — it's just the new end container. The true common ancestor (the parent of both sibling nodes) is computed later by DoSetRange → UpdateCommonAncestorIfNecessary.

Perhaps, nsRange::CharacterDataChanged does not need to do it by itself...

Comment 1

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)(PTO: 9/19-9/27)]

Oh, when aContent is split, the new node has not been inserted to the DOM yet. So, nsRange needs to do that.

Comment 2

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)(PTO: 9/19-9/27)]

Attachment: Bug 2072095 - Make `nsRange::CharacterDataChanged` maintain selection state of new `Text` and its closest common inclusive ancestor at split correctly r=jjaschke!

If the range starts from the old Text and ends in new Text, the
closest common inclusive ancestor is the parent element, but current
code always treats the new Text as the closest common inclusive
ancestor.

Comment 3

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)(PTO: 9/19-9/27)]

This is caused by a regression of bug 2069772. So, we have to fix this soon.

Comment 4

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 2069772

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/26694a6cbac7
https://hg.mozilla.org/integration/autoland/rev/a4dffbf0b408
Make `nsRange::CharacterDataChanged` maintain selection state of new `Text` and its closest common inclusive ancestor at split correctly r=jjaschke

Comment 6

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/62842 for changes under testing/web-platform/tests

Comment 7

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/a4dffbf0b408

Comment 8

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot