[GHC] #15716: GHC hangs on default implementation of type family

[GHC]

#15716: GHC hangs on default implementation of type family
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        Reporter:  Heimdell          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:
       Component:  Compiler          |              Version:  8.4.1
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by int-index):

 I cannot reproduce the hang on 8.4.3, I get an error instead:

 {{{
 A.hs:10:28: error:
     • Expecting one more argument to ‘ExceptT (Error comp)’
       Expected kind ‘* -> *’,
         but ‘ExceptT (Error comp)’ has kind ‘(* -> *) -> * -> *’
     • In the type ‘ExceptT (Error comp)’
       In the default type instance declaration for ‘ComponentT’
       In the class declaration for ‘Component’
    |
 10 |     type ComponentT comp = ExceptT (Error comp)
    |
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15716#comment:2>
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