Non-deterministic pure code in Data.Typeable

Comparing the result of 'typeOf ()' performed in different threads sometimes yields true and sometimes false. To reproduce compile the attached source file with

ghc-7.0.3 -threaded -rtsopts TypeRepEq.hs

And execute it in a shell loop. Looping the inside the Haskell program will usually not show the bug.

while true ; do ./TypeReqEq +RTS -N ; done

Every program run will print either "Ok" or "typeOf () /= typeOf ()". The latter would indicate the bug.

The issue has been discussed on the glasgow-haskell-users mailing list in this thread: http://thread.gmane.org/gmane.comp.lang.haskell.glasgow.user/20754

Different people said that they can reproduce the bug on Mac OS X and Linux with different versions of GHC 6.12.x and 7.0.x. GHC 7.2 does not show the bug.

Trac metadata

Trac field	Value
Version	7.0.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	libraries/base
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	jmg@gaillourdet.net
Operating system
Architecture