632030 - Reflect.parse doesn't handle doubly-declared variables correctly

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Jason Orendorff [:jorendorff]]

Given this program:
    function g(x) { var x; }
Reflect.parse sees this:
    function g(x) { var x = x; }

This is a little strange, but I don't think the difference is observable.

But Reflect.parse also gives the same output for
    f.p = 1; var f; f.p; function f(){}
and
    f.p = 1; var f = function f(){}; f.p; function f(){}
and these are definitely two different programs. The first evals to 1; the
second evals to undefined.

Comment 1

[Dave Herman [:dherman]]

Attachment: handle duplicate var bindings (!!declarator->pn_used)

Another undocumented case in jsparse.h. :)

When a var declaration is a duplicate of a funarg or function declaration, its TOK_NAME declarator node has pn_used set, and the pn_lexdef variant of the union is supposed to be used, not the pn_expr variant.

This patch fixes the missing case in jsreflect, adds the information to the jsparse.h documentation comment, and adds test cases for this bug.

Dave

Comment 2

[Dave Herman [:dherman]]

Attachment: fixed broken test case

Oops, there was a busted test case.

Dave

Comment 3

[Dave Herman [:dherman]]

http://hg.mozilla.org/tracemonkey/rev/56ea7c0ebe16

Comment 4

[Chris Leary [:cdleary] (not checking bugmail)]

cdleary-bot mozilla-central merge info:
http://hg.mozilla.org/mozilla-central/rev/56ea7c0ebe16