[GHC] #11535: Derived instance of Read/Show causes runtime exception for infix Unicode value constructors

[GHC]

#11535: Derived instance of Read/Show causes runtime exception for infix Unicode
value constructors
-------------------------------------+-------------------------------------
        Reporter:  nushio            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:  unicode
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #1544, #11529     |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nushio):

 Thank you very much, thomie! With that help now I have located the origin
 of this bug:

 {{{
 > readPrec_to_S (expectP $ L.Symbol ":+") 0 ":+"
 [((),"")]
 > readPrec_to_S (expectP $ L.Symbol ":☆") 0 ":☆"
 []
 >
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11535#comment:5>
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