Do not create unresolved variables when parsing arrow functions lazily

Do not create unresolved variables when parsing arrow functions lazily

Arrow function parameter lists are parsed as expressions. When an identifier
is found a VariableProxy is created and added to the list of unresolved
variables for the scope. When parsing a function lazily, the scope has been
already resolved, so with this patch only the VariableProxy is created,
without adding it as an unresolved variable in the scope.

BUG=v8:3501
LOG=Y

Committed: https://crrev.com/91b87e7a2884b3322f48dd9cf532eb0e8b462029
Cr-Commit-Position: refs/heads/master@{#26328}

[aperez, 2015-01-28 19:22:27]

aperez@igalia.com changed reviewers:
+ wingo@igalia.com

[marja, 2015-01-29 09:53:00]

marja@chromium.org changed reviewers:
+ marja@chromium.org

[marja, 2015-01-29 09:53:01]

https://codereview.chromium.org/880253004/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/880253004/diff/1/src/parser.cc#newcode1078
src/parser.cc:1078: result = expression->AsFunctionLiteral();
Why are setting parsing_lazy_arrow_parameters_ to true and false so far apart
(conceptually)? Can we set it to false right after ParseExpression here? (Then
it would be trivial to see that it is actually set back to false after we're
done.)

[aperez, 2015-01-29 14:38:04]

https://codereview.chromium.org/880253004/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/880253004/diff/1/src/parser.cc#newcode1078
src/parser.cc:1078: result = expression->AsFunctionLiteral();
On 2015/01/29 09:53:01, marja wrote:
> Why are setting parsing_lazy_arrow_parameters_ to true and false so far apart
> (conceptually)? Can we set it to false right after ParseExpression here? (Then
> it would be trivial to see that it is actually set back to false after we're
> done.)

That does not work.

ParseExpression() here parses the whole arrow function, including the body,
which can itself en up calling ParseExpression().

The flag has to be active only for the “expressions” inside the parameter list
of the arrow function, that's why the flag is set to “false” in
DeclareArrowParametersFromExpression(): at that point it's certain that at least
one entire arrow function parameter list has been parsed.

Other arrow functions contained inside the top-level arrow function being parsed
lazily are always parsed eagerly, so for those the flag will be always “false”
because their parsing has not been started by ParseLazy().

I hope it is clearer now why the flag is reset inside
DeclareArrowParametersFromExpression().

[marja, 2015-01-29 14:46:24]

Ah, right, yes. lgtm.

[aperez, 2015-01-29 15:23:16]

The CQ bit was checked by aperez@igalia.com

[commit-bot: I haz the power, 2015-01-29 15:23:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/880253004/1

[commit-bot: I haz the power, 2015-01-29 15:53:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-29 15:53:26]

Patchset 1 (id:??) landed as
https://crrev.com/91b87e7a2884b3322f48dd9cf532eb0e8b462029
Cr-Commit-Position: refs/heads/master@{#26328}