[GHC] #11144: Custom type errors need tidying

[GHC]

#11144: Custom type errors need tidying
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           Reporter:  goldfire       |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  7.11
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 This is an excerpt from
 `testsuite/tests/typecheck/should_fail/CustomTypeErrors02.stderr`:

 {{{
 CustomTypeErrors02.hs:17:1: error:
     The type 'a_aES -> a_aES' cannot be represented as an integer.
     When checking that ‘err’ has the inferred type
       err :: (TypeError ...)
 }}}

 We should tidy these types before printing.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11144>
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