1101265 - Infinite automatic semicolon insertion before invalid arrow function syntax.

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Tooru Fujisawa [:arai]]

Parser falls into infinite loop with following code:

  1
  )=>

Semicolon is inserted automatically and infinitely before TOK_RP,
because primaryExpr returns null literal for TOK_RP without consuming any token.

Comment 1

[Tooru Fujisawa [:arai]]

Attachment: Parse empty arrow function parameter only in the right place.

TOK_RP in primaryExpr is allowed only if it's just after TOK_LP.

Comment 2

[Tooru Fujisawa [:arai]]

This seems to be the regression by bug 846406.
Confirmed that this happens on Nightly 22.0a1(2013-03-20), with evaluating following code in console:

  eval("1\n)=>")

and memory usage grows rapidly.

Comment 3

[Tooru Fujisawa [:arai]]

Try run is green: https://treeherder.mozilla.org/ui/#/jobs?repo=try&revision=22bf87b96a28

Comment 4

[Tooru Fujisawa [:arai]]

Comment on attachment 8525036 [details] [diff] [review]
Parse empty arrow function parameter only in the right place.

clearing r? for now,
I'll post the fixed one after try run.

Comment 5

[Tooru Fujisawa [:arai]]

Attachment: Simplify parsing empty arrow function parameter.

Green on try run: https://treeherder.mozilla.org/ui/#/jobs?repo=try&revision=e7720384e27e

Comment 6

[Jeff Walden [:Waldo]]

Comment on attachment 8535983 [details] [diff] [review]
Simplify parsing empty arrow function parameter.

Review of attachment 8535983 [details] [diff] [review]:
-----------------------------------------------------------------

::: js/src/frontend/Parser.cpp
@@ +8110,5 @@
> +        // with no params: `() => body`.
> +        tokenStream.consumeKnownToken(next);
> +
> +        if (!tokenStream.peekToken(&next))
> +            return null();

I was going to say add a test for this to that big test with all the @ in it...but such a test already exists in that test.  \o/

Comment 7

[Tooru Fujisawa [:arai]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/5ac338f56e42

Comment 8

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/5ac338f56e42