[GHC] #12595: Linker failure: multiple definition of

[GHC]

#12595: Linker failure: multiple definition of
-------------------------------------+-------------------------------------
           Reporter:                 |             Owner:
  MikolajKonarski                    |
               Type:  bug            |            Status:  new
           Priority:  high           |         Milestone:  8.0.2
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Linux
       Architecture:  x86_64         |   Type of failure:  GHC rejects
  (amd64)                            |  valid program
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #10531
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Linker fails on a normal project built with cabal (-O1), both on my home
 machine (GNU gold (GNU Binutils for Ubuntu 2.22) 1.11) and on travis with
 GHC 8.0.1:

 https://travis-ci.org/LambdaHack/LambdaHack/jobs/159457149#L589

 and with head:

 https://travis-ci.org/LambdaHack/LambdaHack/jobs/159457156#L602

 It compiles fine with -O0 (but if fails with -O2):

 https://travis-ci.org/LambdaHack/LambdaHack/jobs/159457144

 with older GHCs:

 https://travis-ci.org/LambdaHack/LambdaHack/jobs/159457155

 and after the symbol the linker complains about is removed:

 https://travis-ci.org/LambdaHack/LambdaHack/jobs/159506870

 As seen on travis, the way to reproduce it is just cabal install of

 https://github.com/LambdaHack/LambdaHack/commit/0d2bbd6eadca7a10292ab67ab1fa708b4c20aaf6

 which also shows the offending line.

 I took the liberty of adding it to 8.0.2 milestone, because if it affects
 all x86_64 machines, it's pretty serious. Please feel free to downgrade.

 If the bug is confirmed, I can attempt creating a small reproducing case,
 but it would require gtk, so it would compile forever anyway.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12595>
GHC <http://www.haskell.org/ghc/>
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