1207368 - Intermittent test_bug429954.xul | application crashed [@ nsScriptErrorWithStack::AddRef()]

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Comment 1

[Legacy TBPL/Treeherder Robot]

log: https://treeherder.mozilla.org/logviewer.html#?repo=mozilla-inbound&job_id=14503745
repository: mozilla-inbound
start_time: 2015-09-22T09:57:10
who: wkocher[at]mozilla[dot]com
machine: t-yosemite-r5-0038
buildname: Rev5 MacOSX Yosemite 10.10 mozilla-inbound debug test mochitest-other
revision: da185719b98e

TEST-UNEXPECTED-FAIL | widget/tests/test_bug429954.xul | application terminated with exit code 1
PROCESS-CRASH | widget/tests/test_bug429954.xul | application crashed [@ nsScriptErrorWithStack::AddRef()]
TEST-UNEXPECTED-FAIL | leakcheck | default process: missing output line for total leaks!
Return code: 1
No tests run or test summary not found

Comment 2

[Andrew McCreight [:mccr8]]

See bug 1210747 for an explanation.

Comment 3

[Andrew McCreight [:mccr8]]

Attachment: Use swap() instead of forget() to remove MessageElement::mMessage.

Using forget() to extract mMessage from MessageElement ends up going
from nsCOMPtr<T> to already_AddRefed<T> to nsCOMPtr<T>. For the second
step, the compiler can't tell that the already_AddRefed<T> came from a
canonical nsCOMPtr, so it calls Assert_NoQueryNeeded() in debug
builds. This in turn causes a QI, which does an AddRef. That is bad
because we're not on the main thread, and mMessage is
main-thread-only, so we get an assertion.

This patch works around that by using swap directly between two
nsCOMPtr<>, which avoids the Assert_NoQueryNeeded().

I called the method "swapMessage" rather than "swap" to emphasize that
we are not swapping the whole MessageElement, but just one part of
it. I find the existing forget() name to be confusing.

try run: https://treeherder.mozilla.org/#/jobs?repo=try&revision=c3ae9760c82c

Comment 4

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/5845fb9f14cf

Comment 5

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/5845fb9f14cf