1199296 - Don't allow legacy generator yield in method definitions

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[André Bargull [:anba]]

Tests:
---
js> (new (class {constructor(){ yield 2 }})).next()
2

js> ({m(){ yield 2 }}).m().next()
2

js> Object.getOwnPropertyDescriptor({get m() { yield 2 }}, "m").get().next()
2
---

Expected: Throws SyntaxError
Actual: Parsed as legacy generator

Comment 1

[Eric Faust [:efaust]]

Attachment: Fix

OK, so, this is pretty stupid, since this is not exposed to the web by default, but in case people are explicitly setting version numbers, we should not allow this. Here's a fix.

Comment 2

[Eric Faust [:efaust]]

Attachment: Fix

Oops, helps if the tests actually fail in the before vs after trial.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/fab721467f68
Don't allow method definitions to be legacy generators. (r=shu)

Comment 4

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

Backed out in https://hg.mozilla.org/integration/mozilla-inbound/rev/b3145407c4c3 for mass bustage like 

https://treeherder.mozilla.org/logviewer.html#?job_id=31593500&repo=mozilla-inbound

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/79b119d86a4c
Don't allow method definitions to be legacy generators. (r=shu, r=evilpie, r=jaws)

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/28ff935d4af9
Fix up mochitest(cl) failures r=mconley

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/79b119d86a4c
https://hg.mozilla.org/mozilla-central/rev/28ff935d4af9

Comment 8

[Kohei Yoshino]

Posted the site compatibility doc: https://www.fxsitecompat.com/en-CA/docs/2016/legacy-generator-function-is-no-longer-allowed-in-method-definitions/

Comment 9

[Florian Scholz (Open Web Docs)]

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Method_definitions#Shorthand_generator_methods
https://developer.mozilla.org/en-US/Firefox/Releases/51#JavaScript