539488 - var statements for existing, read-only/permanent properties should not be errors (http://myuh.hawaii.edu/cp/home/loginf is blank)

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Satoru Shinagawa]

User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.3a1pre) Gecko/20100113 Minefield/3.7a1pre
Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.3a1pre) Gecko/20100113 Minefield/3.7a1pre

This site http://myuh.hawaii.edu/cp/home/loginf doesn't show anything with Minefield. This started with 01-12-2010 build.

Reproducible: Always

Steps to Reproduce:
1. Simple access http://myuh.hawaii.edu/cp/home/loginf
2. Nothing show up.
3. No problem with the latest version of Firefox
Actual Results:  
Web page doesn't show up

Expected Results:  
Web page show sup

Comment 1

[Ria Klaassen (not reading all bugmail)]

Confirmed with latest trunk on Windows Vista. Is caused by one of the JavaScript checkins:
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=502ed2576efc&tochange=cd2559411e26

Comment 2

[Ria Klaassen (not reading all bugmail)]

The problem is still present in the latest tracemonkey.

Comment 3

[Ria Klaassen (not reading all bugmail)]

Let's put the URL in the summary to make it distinctive.

Comment 4

[David Mandelin [:dmandelin]]

I bisected the regression to here:

changeset:   36848:bf7016ea5dba
user:        Jeff Walden <[e-mail]>
date:        Thu Jan 07 00:17:10 2010 -0600
summary:     Support embedding of |undefined| in lookupswitch, needed to fix bustage in a Mochitest where use of |case undefined| results in that value being embedded in the lookup table, now that |undefined| is an immutable global property.  Anticipatory r=jorendorff, real review on this coming soon...

Comment 5

[Jeff Walden [:Waldo]]

Awesome, first blood to me!  I'll look at this first thing tomorrow morning.

Comment 6

[Jeff Walden [:Waldo]]

http://myuh.hawaii.edu/js/clientsniffer.js contains a top-level |var undefined|, which we treat as trying to redeclare a constant.  Looking at ES5 to see what we should be doing here, I kind of doubt this is correct...

Comment 7

[Jeff Walden [:Waldo]]

Yeah, I don't think current behavior is right.  |var foo| where |foo| is a non-writable, non-configurable property, according to 10.5 Declaration Binding Instantiation, should do nothing, because the HasBinding call in step 8b returns true.

Comment 8

[Sylvain Pasche]

This also affects the Flickr Organizer (http://www.flickr.com/photos/organize/).

Comment 10

[Jeff Walden [:Waldo]]

Attachment: Patch

Comment 11

[Jeff Walden [:Waldo]]

http://hg.mozilla.org/tracemonkey/rev/a19af25a5ddc

Incidentally, for those not following closely, the test in that push/patch is probably one of SpiderMonkey's more "special" tests.  :-)  The non-boilerplate portion consists entirely of:

  var undefined;

Comment 13

[Robert Sayre]

http://hg.mozilla.org/mozilla-central/rev/7e68181ddedb

Comment 14

[Robert Sayre]

http://hg.mozilla.org/mozilla-central/rev/a19af25a5ddc

Comment 15

[Bob Clary [:bc] (inactive)]

fixed manifest http://hg.mozilla.org/tracemonkey/rev/3970759ca2c1