[GHC] #9662: stack overflow in type checker

[GHC]

#9662: stack overflow in type checker
-------------------------------------+-------------------------------------
       Reporter:  Lemming            |                   Owner:
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  Compiler           |                 Version:  7.8.3
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:  Compile-
     Blocked By:                     |  time crash
Related Tickets:                     |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
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 The attached program causes a stack overflow when loading into ghci-7.8.3
 or ghci-7.9.20140929:

 {{{
 $ ghci-7.8.3 -Wall BackpermuteTypeLoop.hs
 GHCi, version 7.8.3: http://www.haskell.org/ghc/  :? for help
 Loading package ghc-prim ... linking ... done.
 Loading package integer-gmp ... linking ... done.
 Loading package base ... linking ... done.
 [1 of 1] Compiling BackpermuteTypeLoop ( BackpermuteTypeLoop.hs,
 interpreted )
 *** Exception: stack overflow
 }}}

 I have no idea, what's going on. The problem may be even not critical,
 because the program is not type-correct anyway. If you replace the `id`
 argument by the out-commented `modify` argument, you will get a nice type
 error message.

 The problem arised when using the Accelerate framework and it involves the
 `modify` function which helps tupling function arguments and untupling
 function results.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9662>
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