[ruby-core:42532] [ruby-trunk - Bug #6008][Rejected] {a: 1}.hash not consistent over VM restarts

Issue #6008 has been updated by Yusuke Endoh.

Status changed from Feedback to Rejected

When objects a and b are in different VM, a.eql?(b) does not
make sense.  If you pass the either object from one VM to the
other in some way (such as using Marshal), a.eql?(b) will be
satisfied, and then a.hash == b.hash will be also satisfied
in the VM.

Theory aside, the behavior (changing the value in each run)
is intended for security reason.  So we will not change the
behavior.

-- 
Yusuke Endoh <[e-mail]>
----------------------------------------
Bug #6008: {a: 1}.hash not consistent over VM restarts
https://bugs.ruby-lang.org/issues/6008

Author: Jens Berlips
Status: Rejected
Priority: Normal
Assignee: 
Category: core
Target version: 1.9.3
ruby -v: ruby 1.9.3p0 (2011-10-30 revision 33570) [x86_64-darwin11.0.0]


$ ruby -e 'puts ({a: 1}.hash)'
-2419336229553239378
$ ruby -e 'puts ({a: 1}.hash)'
-4506930541181251952
$ ruby -e 'puts ({a: 1}.hash)'
2108665473238231010
$ ruby -e 'puts ({a: 1}.hash)'
-3675793335936991568

But if you go to rvm 1.8.7

ruby -e 'puts ({:a => 1}.hash)'
425023
ruby -e 'puts ({:a => 1}.hash)'
425023
ruby -e 'puts ({:a => 1}.hash)'
425023

The documentation read:

> Generates a Fixnum hash value for this object. This function must have the property that a.eql?(b) implies a.hash == b.hash. The hash value is used by class Hash. Any hash value that exceeds the capacity of a Fixnum will be truncated before > being used.

Which implies that you should get the behaviour in 1.8.7.

Regards, 
Jens



-- 
http://bugs.ruby-lang.org/