New subject: [GHC] #12097: DuplicateRecordFields appears not to work in GHCi (was: DuplicateRecordFields appears not to work in)

21 May 2016


      #12097: DuplicateRecordFields appears not to work in
-------------------------------------+-------------------------------------
           Reporter:  bgamari        |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.0.2
          Component:  Compiler       |           Version:  8.0.1
  (Type checker)                     |
           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:
-------------------------------------+-------------------------------------
 This was
 [[https://www.reddit.com/r/haskell/comments/4kdzp2/announce_its_official_ghc_801_has_been_released/d3e6syc|noticed]]
 shortly after the 8.0.1 announcement,

 {{{
 $ ghci
 GHCi, version 8.0.1: http://www.haskell.org/ghc/  :? for help
 Loaded GHCi configuration from /home/ben/.ghci
 λ> :set -XDuplicateRecordFields
 λ> data A = A {test :: String}
 λ> data B = B {test :: Int}
 λ> print $ test (A 42)

 <interactive>:4:9: error:
     Ambiguous occurrence ‘test’
     It could refer to either the field ‘test’,
                              defined at <interactive>:2:13
                           or the field ‘test’, defined at
 <interactive>:3:13
 }}}

 The equivalent program compiled as a module works as expected,
 {{{#!hs
 {-# LANGUAGE DuplicateRecordFields #-}

 module Hi where
 data A = A { test :: Int }    deriving Show
 data B = B { test :: String } deriving Show

 x :: A
 x = A 42

 main = do
     print x
     print (A 42)
 }}}
 {{{
 $ runghc Hi.hs
 A {test = 42}
 A {test = 42}
 }}}

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12097
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler

[GHC] #12097: DuplicateRecordFields appears not to work in

GHC

GHC

GHC

GHC

tags

participants (1)