Issue 11551 in dart: dart2js: identical(NaN, NaN) should be true.

[da...@googlecode.com]

Status: Triaged
Owner: ----
CC: ngeo...@google.com
Labels: Type-Defect Priority-Unassigned Area-Dart2JS

New issue 11551 by l...@google.com: dart2js: identical(NaN, NaN) should be
true.
http://code.google.com/p/dart/issues/detail?id=11551

The spec now says explicitly that identical(c1, c2) is true if both c1 and
c2 are doubles representing NaN.
Dart2js generates code that makes
var n = double.NAN;
print(identical(n, n));
print false. The code seems to be:
function() {
$.print(0 / 0 === 0 / 0);
}


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[da...@googlecode.com]

Updates:
Labels: -Priority-Unassigned Priority-Medium Milestone-M6

Comment #1 on issue 11551 by kas...@google.com: dart2js: identical(NaN,

NaN) should be true.
http://code.google.com/p/dart/issues/detail?id=11551

(No comment was entered for this change.)

[da...@googlecode.com]

Comment #3 on issue 11551 by l...@google.com: dart2js: identical(NaN, NaN)

should be true.
http://code.google.com/p/dart/issues/detail?id=11551

Identical also fails for -0/0:
main() { print(identical(-0.0, 0.0)); } // prints true

[da...@googlecode.com]

Comment #6 on issue 11551 by srawl...@google.com: dart2js: identical(NaN,

NaN) should be true.
http://code.google.com/p/dart/issues/detail?id=11551

Maybe this can be merged into Issue 15317. That issue is certainly newer,
but I think there is a clear path forward there.

[da...@googlecode.com]

Comment #7 on issue 11551 by l...@google.com: dart2js: identical(NaN, NaN)

should be true.
http://code.google.com/p/dart/issues/detail?id=11551

I think this is independent of Issue 15317, which is a request for changing
the spec for NaN identity. Whether the spec changes or not, dart2js is
implementing neither the current or the proposed spec, and doesn't
implement the spec on identical(0.0,-0.0).

[da...@googlecode.com]

Comment #10 on issue 11551 by eer...@google.com: dart2js: identical(NaN,
NaN) should be true.
https://code.google.com/p/dart/issues/detail?id=11551

The fact that identical(_,_) returns false on a pair of NaNs also makes
this co19 test fail, in three distinct locations:

Language/12_Expressions/00_Object_Identity/1_Object_Identity_A02_t02.

[da...@googlecode.com]

Comment #11 on issue 11551 by eer...@google.com: dart2js: identical(NaN,

NaN) should be true.
https://code.google.com/p/dart/issues/detail?id=11551

The fact that identical(_,_) returns false on a pair of NaNs also makes

this co19 test fail, in the last line:

Language/12_Expressions/00_Object_Identity/1_Object_Identity_A06_t01.

[da...@googlecode.com]

Comment #12 on issue 11551 by srd...@google.com: dart2js: identical(NaN,

NaN) should be true.
https://code.google.com/p/dart/issues/detail?id=11551

The spec says:
identical(c1, c2): Both c1 and c2 represent a NaN value with the same
underlying bit
pattern.

identical(double.NAN, -double.NAN) should return false therefore,