880447 - Permit 'yield yield expr;'

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jason Orendorff [:jorendorff]]

We throw:

    js> function f() { yield yield 1; }
    typein:1:21 SyntaxError: missing ; before statement:
    typein:1:21 function f() { yield yield 1; }

Though if you put in some extra parens, there's nothing wrong with it:

    js> function f() { yield (yield 1); }
    js> dis(f)
    ...
    00001:  one
    00002:  yield
    00003:  yield
    00004:  pop
    00005:  stop

More to the point, ES6 says it's ok:

    AssignmentExpression : YieldExpression

    YieldExpression : yield *_opt AssignmentExpression

(The optional * is covered by bug 666396.)

Comment 1

[Jason Orendorff [:jorendorff]]

Attachment: v1

I was in the neighborhood.

Comment 2

[Till Schneidereit [:till]]

Comment on attachment 765675 [details] [diff] [review]
v1

Review of attachment 765675 [details] [diff] [review]:
-----------------------------------------------------------------

I'm confident my knowledge of the parser is sufficient for this. (Or, just my ability to read code, really.)

Comment 3

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/ad0550c09186