Bug 176573 – `async` should be able to be used as an imported binding name

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Keanu Lee]

According to JS spec (https://tc39.github.io/ecma262/#sec-reserved-words), `async` is not a reserved keyword and should be able to be used as an imported binding name. For example, the following should not throw:

    import * as async from "./client.js";


Repro: https://kindly-physician.glitch.me/ (works in Chrome)

Related: https://github.com/Polymer/polymer-modulizer/issues/197

[Radar WebKit Bug Importer]

<rdar://problem/34833164>

[Yusuke Suzuki]

Created attachment 322964 [details]
Patch

WIP: checking performance

[Yusuke Suzuki]

                         baseline                  patched                                      

closure              0.54239+-0.00583          0.54187+-0.00837       
jquery               7.29268+-0.04093    ^     7.21285+-0.03484       ^ definitely 1.0111x faster

OK, performance is not a problem.

[Yusuke Suzuki]

*** Bug 177986 has been marked as a duplicate of this bug. ***

[Yusuke Suzuki]

Created attachment 322971 [details]
Patch

[Caitlin Potter (:caitp)]

Per `https://tc39.github.io/ecma262/#prod-ImportedBinding`, isn't "await" always an invalid binding name in import declarations? Or am I mis-reading that notation?

[Caitlin Potter (:caitp)]

(In reply to Caitlin Potter (:caitp) from comment #6)
> Per `https://tc39.github.io/ecma262/#prod-ImportedBinding`, isn't "await"
> always an invalid binding name in import declarations? Or am I mis-reading
> that notation?

Ok, I totally misread the title of this bug. Makes perfect sense for "async", nevermind me :)

[Build Bot]

Comment on attachment 322971 [details]
Patch

Attachment 322971 [details] did not pass mac-debug-ews (mac):
Output: http://webkit-queues.webkit.org/results/4778645

New failing tests:
workers/wasm-long-compile.html

[Build Bot]

Created attachment 322996 [details]
Archive of layout-test-results from ews112 for mac-elcapitan

The attached test failures were seen while running run-webkit-tests on the mac-debug-ews.
Bot: ews112  Port: mac-elcapitan  Platform: Mac OS X 10.11.6

[Yusuke Suzuki]

(In reply to Caitlin Potter (:caitp) from comment #7)
> (In reply to Caitlin Potter (:caitp) from comment #6)
> > Per `https://tc39.github.io/ecma262/#prod-ImportedBinding`, isn't "await"
> > always an invalid binding name in import declarations? Or am I mis-reading
> > that notation?
> 
> Ok, I totally misread the title of this bug. Makes perfect sense for
> "async", nevermind me :)

np ;), this is for “async”.

[Yusuke Suzuki]

(In reply to Build Bot from comment #8)
> Comment on attachment 322971 [details]
> Patch
> 
> Attachment 322971 [details] did not pass mac-debug-ews (mac):
> Output: http://webkit-queues.webkit.org/results/4778645
> 
> New failing tests:
> workers/wasm-long-compile.html

This is unrelated.

[WebKit Commit Bot]

Comment on attachment 322971 [details]
Patch

Clearing flags on attachment: 322971

Committed r223022: <http://trac.webkit.org/changeset/223022>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Ryan Haddad]

This change introduced 18 test262 failures. Here is the output for one of the tests:

test262.yaml/test262/test/language/expressions/async-arrow-function/escaped-async.js.default: Expected uncaught exception with name 'SyntaxError' but exception value is not instance of this exception class
test262.yaml/test262/test/language/expressions/async-arrow-function/escaped-async.js.default: Exception: Test262: This statement should not be evaluated.
test262.yaml/test262/test/language/expressions/async-arrow-function/escaped-async.js.default: ERROR: Unexpected exit code: 3
FAIL: test262.yaml/test262/test/language/expressions/async-arrow-function/escaped-async.js.default

https://build.webkit.org/builders/Apple%20El%20Capitan%20Debug%20Test262%20%28Tests%29/builds/3621

[Ryan Haddad]

Reverted r223022 for reason:

This change introduced 18 test262 failures.

Committed r223062: <http://trac.webkit.org/changeset/223062>

[Yusuke Suzuki]

Created attachment 323262 [details]
Patch

[Yusuke Suzuki]

Committed r223124: <http://trac.webkit.org/changeset/223124>