[GHC] #13695: Highly nested UNPACKed data causes panic

[GHC]

#13695: Highly nested UNPACKed data causes panic
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        Reporter:  ryanreich     |                Owner:  (none)
            Type:  bug           |               Status:  new
        Priority:  high          |            Milestone:  8.2.1
       Component:  Compiler      |              Version:  8.2.1-rc2
      Resolution:                |             Keywords:
Operating System:  Linux         |         Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown  |            Test Case:
      Blocked By:                |             Blocking:
 Related Tickets:  #3990         |  Differential Rev(s):
       Wiki Page:                |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"8fe37a0222517c3af5ffbb793fa738ad7f3eac3d/ghc"
 8fe37a02/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="8fe37a0222517c3af5ffbb793fa738ad7f3eac3d"
 Account for IfUnpackCo in freeNamesIfDecl

 We were simply failing to recognise all the free variables of an
 IfaceDecl, notably the ones in the coercion of an IfUnpackCo.
 Result: the dependency analysis got messed up, so that fingerprint
 calculation went wrong.  Trac #13695 showed it up.

 A test case is tricky but the fix is a solid one.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13695#comment:10>
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