[GHC] #11985: Core lint error on record syntax update/pattern synonym

[GHC]

#11985: Core lint error on record syntax update/pattern synonym
-------------------------------------+-------------------------------------
           Reporter:  Iceland_jack   |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.1
           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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 While on a flight I discovered some errors, if you load a file using
 record syntax for pattern synonyms:

 {{{#!hs
 module Foo where

 pattern Pair{x, y} = (x, y)
 }}}

 and load it with `-dcore-lint`:

 {{{
 $ ghci -dcore-lint -ignore-dot-ghci -XPatternSynonyms /tmp/Foo.hs
 GHCi, version 8.1.20160419: http://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling Foo              ( /tmp/Foo.hs, interpreted )
 Ok, modules loaded: Foo.
 *Foo> (1, 2) { x = 10 }
 *** Core Lint errors : in result of desugar expression ***
     [...]
 }}}

 full error message attached.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11985>
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