Re: [GHC] #14507: Core Lint error with Type.Reflection and pattern synonyms

5 Jan 2018

      #14507: Core Lint error with Type.Reflection and pattern synonyms
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
                                     |  PatternSynonyms, TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones ):

 In [changeset:"40cbab9afe52fbc780310e880912b56370065a62/ghc"
 40cbab9a/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="40cbab9afe52fbc780310e880912b56370065a62"
 Fix another obscure pattern-synonym crash

 This one, discovered by Iceland Jack (Trac #14507), shows
 that a pattern-bound coercion can show up in the argument
 type(s) of the matcher of a pattern synonym.

 The error message isn't great, but at least we now rightly
 reject the program.
 }}}

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14507#comment:5
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