1782151 - [CTW] Assertion failure: mCachedFields, at .../accessible/ipc/RemoteAccessibleBase.cpp:403

Status: RESOLVED FIXED

(Core :: Disability Access APIs, defect)

Description

[James Teh [:Jamie]]

I'm seeing this sometimes when loading/refreshing/moving away from some pages; e.g. https://webcache.googleusercontent.com/search?q=cache:YfR4odEq9z4J:https://github.com/processhacker/processhacker/blob/master/ProcessHacker/notifico.c+&cd=7&hl=en&ct=clnk&gl=au&client=firefox-b-d

Assertion failure: mCachedFields, at C:/Users/jamie/src/gecko/accessible/ipc/RemoteAccessibleBase.cpp:403
#01: mozilla::a11y::RemoteAccessibleBase<mozilla::a11y::RemoteAccessible>::RetrieveCachedBounds (C:\Users\jamie\src\gecko\accessible\ipc\RemoteAccessibleBase.cpp:403)
#02: mozilla::a11y::RemoteAccessibleBase<mozilla::a11y::RemoteAccessible>::BoundsWithOffset (C:\Users\jamie\src\gecko\accessible\ipc\RemoteAccessibleBase.cpp:505)
#03: mozilla::a11y::RemoteAccessibleBase<mozilla::a11y::RemoteAccessible>::Bounds (C:\Users\jamie\src\gecko\accessible\ipc\RemoteAccessibleBase.cpp:613)
#04: mozilla::a11y::RemoteAccessible::Bounds (C:\Users\jamie\src\gecko\accessible\ipc\win\RemoteAccessible.cpp:233)
#05: mozilla::a11y::MsaaAccessible::accLocation (C:\Users\jamie\src\gecko\accessible\windows\msaa\MsaaAccessible.cpp:1530)
#06: nvdaInProcUtils_winword_expandToLine[C:\Program Files (x86)\NVDA\lib64\alpha-23364,b7dd32fc\nvdaHelperRemote.dll +0x714d4]
...

It's entirely possible that mCachedFields might be null when a client tries to query the location because the cache is pushed separately from the tree and a client call could arrive between those two IPDL calls. Before bug 1771271, we allowed mCachedFields to be null on this, but not on an ancestor. After bug 1771271, we allow (but assert for) null in both cases.

In bug 1771271, we weren't sure why mCachedFields should be null on an ancestor. However, this is probably possible in the case of OOP iframes, since IPDL calls from both documents could be interspersed.

I think we should just remove the assert.

Comment 1

[James Teh [:Jamie]]

Attachment: Bug 1782151: Don't assert that mCachedFields isn't null in RemoteAccessibleBase::RetrieveCachedBounds.

This is possible if a client query arrives between the two IPDL calls for the tree and the cache.
This might even happen for an ancestor in the case of an OOP iframe, where IPDL calls for the two documents might be interspersed.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1771271

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/22c38fa47796
Don't assert that mCachedFields isn't null in RemoteAccessibleBase::RetrieveCachedBounds. r=morgan

Comment 4

[Iulian Moraru]

https://hg.mozilla.org/mozilla-central/rev/22c38fa47796