1494281 - React DevTools is broken in the latest Fx64 Nightly

Status: RESOLVED FIXED

(DevTools :: General, defect, P1)

Description

[Patrick Brosset <:pbro>]

This was originally filed in https://github.com/facebook/react-devtools/issues/1169

This seems to be a regression caused by a changed in Firefox, not in the extension, so filing it here for investigation.

STR:
- open the latest nightly
- install the React DevTools from AMO https://addons.mozilla.org/en-US/firefox/addon/react-devtools/
- open a page that uses react (I think reactjs.org will do)
- open the toolbox

==> the React DevTools tab is not displayed in the toolbox, and the following 2 JS errors appear in the browser console over and over again:

Cannot set the context DevTools target twice ExtensionParent.jsm:749
set devToolsTarget
resource://gre/modules/ExtensionParent.jsm:749:13
global.getDevToolsTargetForContext
chrome://browser/content/parent/ext-devtools.js:51:34
InterpretGeneratorResume self-hosted:1255:8 next self-hosted:1210:9 

Unchecked lastError value: Error: An unexpected error occurred main.js:18
createPanelIfReactLoaded
moz-extension://50635c1b-0f3b-4cb5-a749-f657197dda92/build/main.js:18:25

Comment 1

[Patrick Brosset <:pbro>]

I did a mozregression to pinpoint the cause. Here's the pushlog: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=bf90894b0f2eb4aa876496a71dae66107559dd42&tochange=02308fea5840d131e7684e330563470925aa5472
It points to bug 1485676.

Alex: could you please look at the problem?

Comment 2

[Alexandre Poirot [:ochameau]]

That might be this line:
  https://searchfox.org/mozilla-central/source/browser/components/extensions/parent/ext-devtools.js#51
Causing a race around target creation.

Comment 3

[Alexandre Poirot [:ochameau]]

Yes, that is because of this line, I was able to fix the issue locally.
Now trying to craft a patch for this.

Try build:
  https://treeherder.mozilla.org/#/jobs?repo=try&selectedJob=201695833&revision=c8ec39abc9a8a3b20971f78b3dd4a58c26884344

Comment 4

[Alexandre Poirot [:ochameau]]

Attachment: Bug 1494281 - Fix possible race around devToolsTarget promise creation

MozReview-Commit-ID: DlB05jFPtGL

Comment 5

[Luca Greco [:rpl] [:luca] [:lgreco]]

Comment on attachment 9012259 [details]
Bug 1494281 - Fix possible race around devToolsTarget promise creation

Luca Greco [:rpl] (PTO from 2018-09-24 to 2018-09-28) has approved the revision.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/17311c934402
Fix possible race around devToolsTarget promise creation r=rpl

Comment 7

[Cristian Brindusan [:cbrindusan]]

https://hg.mozilla.org/mozilla-central/rev/17311c934402