[GHC] #10463: Wrong warning with PartialTypeSignatures

30 May 2015


      #10463: Wrong warning with PartialTypeSignatures
-------------------------------------+-------------------------------------
              Reporter:  augustss    |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:
             Component:  Compiler    |           Version:  7.10.1
              Keywords:              |  Operating System:  Unknown/Multiple
          Architecture:              |   Type of failure:  None/Unknown
  Unknown/Multiple                   |        Blocked By:
             Test Case:              |   Related Tickets:
              Blocking:              |
Differential Revisions:              |
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 This program
 {{{#!hs
 {-# LANGUAGE ScopedTypeVariables, PartialTypeSignatures #-}
 f (x :: _) = x ++ ""
 }}}
 gives this warning
 {{{
 Bug.hs:2:9: Warning:
     Found hole ‘_’ with type: [Char]
     Relevant bindings include
       f :: [Char] -> [Char] (bound at Bug.hs:2:1)
     In a pattern type signature: _
     In the pattern: x :: _
     In an equation for ‘f’: f (x :: _) = x ++ ""
 }}}
 But there is no hole, only an _ in a type.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10463
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