Closed
Bug 504590
Opened 15 years ago
Closed 15 years ago
javascript closures strange behavior
Categories
(Core :: JavaScript Engine, defect)
Core
JavaScript Engine
Tracking
()
RESOLVED
FIXED
Tracking | Status | |
---|---|---|
status1.9.1 | --- | ? |
People
(Reporter: salomvary.marton, Assigned: mrbkap)
References
Details
(Keywords: regression, testcase)
Attachments
(2 files)
472 bytes,
text/html
|
Details | |
1.32 KB,
patch
|
brendan
:
review+
|
Details | Diff | Splinter Review |
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.10) Gecko/2009042513 Ubuntu/8.04 (hardy) Firefox/3.0.10 Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1) Gecko/20090624 Firefox/3.5 Under certain circumstances (seems to be related to closures), a javascript function, which should return a _new instance_ of an anonymous function returns always the _same_ function object. Reproducible: Always Steps to Reproduce: 1. run the test code Actual Results: The two objects are equal. (Displays: "result: true,true") Expected Results: The two objects shouldn't be equal. (Should display: "result: false, false") Versions tested: Firefox 3.5 (Linux, Win), and nightly build on Linux (Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2a1pre) Gecko/20090716 Minefield/3.6a1pre) Test code (html): <html> <head> </head> <body id="body"> <script> function create() { return function() { var foo; if (false) { return function() { return foo; }; } foo = Object; return false; }; } var a = create(); var b = create(); document.getElementById('body').innerHTML = 'result: ' + (a == b) + ',' + (a === b) + '<br/> expected: false, false'; </script> </body> </html>
Reporter | ||
Comment 1•15 years ago
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||
Reporter | ||
Updated•15 years ago
|
Version: unspecified → 3.5 Branch
Comment 2•15 years ago
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Testcase confirmed on Windows Vista. Regression range: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=d056669074c7&tochange=57213af4a45d
Assignee: nobody → general
Status: UNCONFIRMED → NEW
Component: General → JavaScript Engine
Ever confirmed: true
Keywords: regression,
testcase
Product: Firefox → Core
QA Contact: general → general
Hardware: x86 → All
Version: 3.5 Branch → Trunk
Assignee | ||
Comment 3•15 years ago
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This is fallout from upvar2. I think we should fix it on the 1.9.1 branch. But it doesn't block.
Blocks: upvar2
status1.9.1:
--- → needstriage
Assignee | ||
Comment 4•15 years ago
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||
The closure forces the inner function to be HEAVYWEIGHT (since it's very hard for the compiler to clear the flag) and we end up falling into the non-null-closure case of JSOP_LAMBDA. That branch avoids cloning if the compiler saw the right parent (which it does in this case) but that, in effect, creates a joined function object, whose semantics we don't quite support yet (see bug 471214).
Comment 5•15 years ago
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Comment on attachment 388970 [details] [diff] [review] Proposed fix Any perf effects of note? Please use more standard (cough, we have two leading forms) FIXME style, preferably FIXME: bug NNNNNN. /be
Attachment #388970 -
Flags: review?(brendan) → review+
Comment 6•15 years ago
|
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http://hg.mozilla.org/mozilla-central/rev/66e5fb8783ef
Status: ASSIGNED → RESOLVED
Closed: 15 years ago
Resolution: --- → FIXED
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Description
•