[GHC] #12061: Allow duplicate record fields in pattern synonyms

[GHC]

#12061: Allow duplicate record fields in pattern synonyms
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           Reporter:  Iceland_jack   |             Owner:
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:
           Keywords:                 |  Operating System:  Unknown/Multiple
  PatternSynonyms                    |
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 `DuplicateRecordFields` seems to not work for pattern synonyms

 {{{#!hs
 {-# Language PatternSynonyms, DuplicateRecordFields, NamedFieldPuns #-}

 pattern A{x} = Just x
 pattern B{x} = Just x
 }}}

 {{{
 tg4t.hs:4:11: error: …
     Multiple declarations of ‘x’
     Declared at: /tmp/tg4t.hs:3:11
                  /tmp/tg4t.hs:4:11
 Compilation failed.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12061>
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