Issue #7676 has been updated by simonrussell (Simon Russell).


At the very least, the documentation for Array#== should be updated to state that it first does an object identity comparison, then calls == only if the objects aren't the same instance.
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Bug #7676: Comparison of Float::NAN in array behaves unexpectedly
https://bugs.ruby-lang.org/issues/7676#change-35307

Author: simonrussell (Simon Russell)
Status: Rejected
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 1.9.3p362 (2012-12-25 revision 38607) [x86_64-linux]


It seems that two arrays containing Float::NAN will be considered equal ([Float::NAN] == [Float::NAN]), despite the fact that Float::NAN != Float::NAN.

Tested and reproduced in 1.8.7p371, 1.9.3p362, 2.0.0preview2. (This bug can be reproduced in Ruby 1.8 as well.)  Results below.

1.8.7 p371
---------

1.8.7 :001 > nan = 0.0/0.0
 => NaN 
1.8.7 :002 > nan == nan
 => false 
1.8.7 :003 > [nan] == [nan]
 => true 

1.9.3 p362
---------

1.9.3p362 :001 > Float::NAN == Float::NAN
 => false 
1.9.3p362 :002 > [Float::NAN] == [Float::NAN]
 => true 

2.0.0 preview2
--------------

2.0.0dev :001 > Float::NAN == Float::NAN
 => false 
2.0.0dev :002 > [Float::NAN] == [Float::NAN]
 => true


-- 
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