1478911 - Improve the error message when yield/await is used inside parameter

Status: RESOLVED FIXED

(Core :: JavaScript Engine, enhancement, P5)

Description

[Tooru Fujisawa [:arai]]

js> async function* f(a = yield) {}
typein:19:22 SyntaxError: yield in default expression:
typein:19:22 async function* f(a = yield) {}
typein:19:22 ......................^
js> async function* f(a = await 10) {}
typein:21:22 SyntaxError: await can't be used in default expression:
typein:21:22 async function* f(a = await 10) {}
typein:21:22 ......................^
js> async function* f([a = yield]) {}
typein:24:23 SyntaxError: yield in default expression:
typein:24:23 async function* f([a = yield]) {}
typein:24:23 .......................^
js> async function* f([a = await]) {}
typein:23:28 SyntaxError: expected expression, got ']':
typein:23:28 async function* f([a = await]) {}
typein:23:28 ............................^

the actual issue is that yield/await cannot be used in parameter, and it's not about whether it's in default expression.
(of course it can appear only in default parameter or destructuring default tho)
we should say something like:
  * yield expression can't be used in parameter
  * await expression can't be used in parameter


other browsers's output:

  Safari
    > function* f(a = yield) {}
    SyntaxError: Unexpected keyword 'yield'. Cannot use yield expression within parameters.
    > async function f(a = await 10) {}
    SyntaxError: Unexpected identifier 'await'. Cannot use await expression within parameters.
  Chrome
    > function* f(a = yield) {}
    Uncaught SyntaxError: Yield expression not allowed in formal parameter
    > async function f(a = await 10) {}
    Uncaught SyntaxError: Illegal await-expression in formal parameters of async function

things to do here:
  1. fix the error message in js/src/js.msg
  2. fix the name of the error message in js/src/js.msg, and its consumers

Comment 1

[mayank.iitkgp98]

I want to solve this issue.

Comment 2

[Tooru Fujisawa [:arai]]

Thanks!

Let me know if you have any question.

here's instruction for preparing development environment and building Firefox.
https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Simple_Firefox_build
also you can look for the error message consumer here https://searchfox.org/

Once you've fixed it locally, please export it as a patch file and attach here, and ask review from me.

Comment 3

[Aditya S]

Can I work on this bug?

Comment 4

[Tooru Fujisawa [:arai]]

mayank is working on this bug (see comment #1).

there are similar bugs under bug 622261,
let me know if you need help finding a bug to work on (bug comment or :arai in #jsapi channel in irc)

Comment 5

[Aditya S]

Can somebody give me some pointers on where to start and also which file should I be looking at to fix this bug?

Comment 6

[shivambalikondwar]

Can i go ahead for this bug

Comment 7

[shivambalikondwar]

i solved it please ,if mayank hasn't done it i can post it in :)

Comment 8

[Tooru Fujisawa [:arai]]

sure, given that there's no activity for a while, you can take this over.

Comment 9

[shivambalikondwar]

sorry i forgot to introduce myself ;
i am an undergrad in engineering and looking up for open source contribution ,setting goals for getting chance to be a part of gsoc and mozilla ;
i have a problem i changed file in my build (files) but now how to i submit it ,please help :)

Comment 10

[Tooru Fujisawa [:arai]]

basic workflow:

  1. clone mozilla-unified (or mozilla-central)
  2. modify file
  3. create a changeset for the modification by "hg commit" command
    a. the commit message should follow this rule https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Committing_Rules_and_Responsibilities#Checkin_comment
  4. export the changeset by "hg export -r . > somewhere/bugNNNN.patch"
  5. attach the file here, and ask review (there's review field in the attachment form)

if you've done 1-2, please try 3-5.

Comment 11

[Anushi Maheshwari[:Anushi1998]]

:arai, Is anybody working on this bug?

Comment 12

[Tooru Fujisawa [:arai]]

I'm not sure who's currently working on, but I'll assign this bug to anyone who posts the patch ;)

Comment 13

[akshitsoni0000]

Is anyone working on this? I am new to opensource and i want take this up.

Comment 14

[Anushi Maheshwari[:Anushi1998]]

Yes I have completed it and will be submitting PR soon :)

Comment 15

[Anushi Maheshwari[:Anushi1998]]

Attachment: bug1478911.patch

Comment 16

[Tooru Fujisawa [:arai]]

Comment on attachment 9007408 [details] [diff] [review]
bug1478911.patch

Review of attachment 9007408 [details] [diff] [review]:
-----------------------------------------------------------------

Thank you for your patch :D

given the expected error message is changed, can you fix the following line as well?
  https://searchfox.org/mozilla-central/rev/37663bb87004167184de6f2afa6b05875eb0528e/js/src/tests/non262/async-functions/await-in-parameters-of-async-func.js#23
this is just a message and this test doesn't fail, but nice to fix :)

Also, please change the first line of the commit message to follow this rule?
  https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Committing_Rules_and_Responsibilities#Commit_message_restrictions
basically, "Bug NNNNNN - description of the change"

::: js/src/js.msg
@@ +188,4 @@
>  MSG_DEF(JSMSG_ARRAY_INIT_TOO_BIG,      0, JSEXN_INTERNALERR, "array initializer too large")
>  MSG_DEF(JSMSG_AS_AFTER_IMPORT_STAR,    0, JSEXN_SYNTAXERR, "missing keyword 'as' after import *")
>  MSG_DEF(JSMSG_AS_AFTER_RESERVED_WORD,  1, JSEXN_SYNTAXERR, "missing keyword 'as' after reserved word '{0}'")
> +MSG_DEF(JSMSG_AWAIT_IN_PARAMETER,        0, JSEXN_SYNTAXERR, "await expression can't be used in parameter")

please align "0" to "1" in the previous line

Comment 17

[Anushi Maheshwari[:Anushi1998]]

Attachment: bug1478911.patch

Comment 18

[Tooru Fujisawa [:arai]]

Comment on attachment 9007410 [details] [diff] [review]
bug1478911.patch

Review of attachment 9007410 [details] [diff] [review]:
-----------------------------------------------------------------

Excellent :D

here's try run, which executes automated tests (with previous patch, but the result should be same)
  https://treeherder.mozilla.org/#/jobs?repo=try&revision=3a8b7bed8badb07801940dd105b903eba2d2864c&group_state=expanded
if it completes without any failure, you can add "checkin-needed" keyword to this bug, so that this patch will be landed shortly.

also, you can mark the previous patch "obsolete" when attaching new patch.
now you can mark it obsolete in attachment details page above.

Comment 19

[Anushi Maheshwari[:Anushi1998]]

Thanks :arai :)

Comment 20

[Tooru Fujisawa [:arai]]

I overlooked that the bug number in the commit message is wrong.
can you fix it to "Bug 1478911" ?

Comment 21

[Tooru Fujisawa [:arai]]

also, when attaching, you can add "r=arai" at the end of the commit message, first line,
and choose "+" for "review" (please declare that you're carrying forward the previous review, in the comment)

the try run looks fine.  after attaching the updated patch, you can add "checkin-needed" keyword.

Comment 22

[Anushi Maheshwari[:Anushi1998]]

Attachment: bug1478911.patch

Carrying forward previous review.

Comment 23

[Tooru Fujisawa [:arai]]

not, "checkin" flag.
add "checkin-needed" to "Keyword" under "Tracking" section

Comment 24

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/5208ae2ec7da
Changed error message and name of error for `JSMSG_AWAIT_IN_DEFAULT` and `JSMSG_YIELD_IN_PARAMETER` and corresponding change in consumer files. r=arai

Comment 25

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/5208ae2ec7da