[GHC] #13778: explicitly bidirectional patterns should not report Recursive definition" when used in view pattern expression position

[GHC]

#13778: explicitly bidirectional patterns should not report Recursive definition"
when used in view pattern expression position
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        Reporter:  heisenbug         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.3
      Resolution:                    |             Keywords:
                                     |  PatternSynonyms
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 simonpj):

 > adding a type signature won't make the error go away

 I didn't claim that it would!

 But you give me an idea.  If you wrote a pattern signature:
 {{{
 pattern One :: Num a  => a
 pattern One <- ((==One) -> True)
   where One = 1
 }}}
 then I think we could soundly suppress the check, without messing up the
 architecture above.  Hmm.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13778#comment:4>
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