[GHC] #15487: "Ambiguos occurrence" error message uses strange qualification

7 Aug 2018


      #15487: "Ambiguos occurrence" error message uses strange qualification
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           Reporter:  j.waldmann     |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.6.1
          Component:  Compiler       |           Version:  8.4.3
           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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 The following text produces an error message that I find somewhat
 confusing. This issue is just about the wording of the message.

 {{{#!hs
 module A (null) where { }
 module B where { import qualified A ; null = 42 ; main = null }
 }}}
 when I load `B` in ghci, I get
 {{{
 B.hs:1:58: error:
     Ambiguous occurrence ‘null’
     It could refer to either ‘A.null’,
                              imported from ‘Prelude’ at B.hs:1:8
                              (and originally defined in ‘Data.Foldable’)
                           or ‘B.null’, defined at B.hs:1:39
 }}}
 I think ".. could refer to A.null" looks strange.
 I would expect `Prelude.null` here, which I do get when I remove "import
 qualified A" from the text of `B`.

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15487
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