[GHC] #8729: Compile crashed with panic! (the 'impossible' happened)

[GHC]

#8729: Compile crashed with panic! (the 'impossible' happened)
---------------------------------------+-----------------------------------
        Reporter:  zabirauf            |            Owner:
            Type:  bug                 |           Status:  closed
        Priority:  high                |        Milestone:  7.6.1
       Component:  Compiler            |          Version:  7.4.1
      Resolution:  fixed               |         Keywords:
Operating System:  Linux               |     Architecture:
 Type of failure:  Compile-time crash  |  Unknown/Multiple
       Test Case:                      |       Difficulty:  Unknown
        Blocking:                      |       Blocked By:
                                       |  Related Tickets:
---------------------------------------+-----------------------------------
Changes (by hvr):

 * status:  new => closed
 * architecture:  x86_64 (amd64) => Unknown/Multiple
 * milestone:   => 7.6.1
 * keywords:  panic! impossible compiler crash =>
 * resolution:   => fixed


Old description:

> The following code results in a compiler crash with error
> ghc: panic! (the 'impossible' happened)
>   (GHC version 7.4.1 for x86_64-unknown-linux):
>         nameModule show{tv a9N}
>
> Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
>
> The code can be found at [http://pastie.org/8692515]

New description:

 The following code results in a compiler crash with error

 {{{
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.4.1 for x86_64-unknown-linux):
         nameModule show{tv a9N}

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

 The code can be found at [http://pastie.org/8692515]

--

Comment:

 Thanks for the report, however this has been fixed in GHC 7.6.1 already,
 which gives the following compile error:

 {{{
 t8729.hs:1:65:
     Illegal deriving item `show'
     In the data declaration for `LinkedList'
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8729#comment:1>
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