[GHC] #14615: Segfault when printing a simple string

25 Dec 2017


      #14615: Segfault when printing a simple string
-------------------------------------+-------------------------------------
           Reporter:  Iceland_jack   |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.2.2
           Keywords:  Christmas      |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 This segfaults on GHC 8.2.1 and 8.3.20171208

 {{{#!hs
 -- Segfault.hs

 main = do
   let xs =
 [1,1,1,1,1,1,5,0,1,1,1,1,1,4,2,4,0,1,1,1,1,4,2,2,2,4,0,1,1,1,4,2,3,2,2,3,4,0,1,1,4,3,2,2,3,2,2,2,4,0,1,4,2,2,3,2,2,2,3,2,2,4,0,4,2,3,2,2,2,3,2,2,3,2,2,4,0,1,1,1,1,1,1,2,0,1,1,1,1,1,1,2]
   let f ?? x = fmap ($ x) f

   putStrLn (traverse ((??) (!!)) xs "\n #%.t")
 }}}

 when running it as

 {{{
 $ runghc -ignore-dot-ghci -dcore-lint -fdefer-type-errors Segfault.hs
 Segmentation fault: 11
 }}}

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14615
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