[GHC] #14642: ‘class C using’ fails to parse with MonadComprehensions

[GHC]

#14642: ‘class C using’ fails to parse with MonadComprehensions
-------------------------------------+-------------------------------------
           Reporter:  Iceland_jack   |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.2.2
           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:
-------------------------------------+-------------------------------------
 `TransformListComp` / `MonadComprehensions` reserve `using` but should
 this not work?

 {{{#!hs
 {-# Language TransformListComp #-}

 class C using
 }}}

 gives

 {{{
 $ ghci -ignore-dot-ghci /tmp/X.hs
 GHCi, version 8.5.20180105: http://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling Main             ( /tmp/X.hs, interpreted )

 /tmp/X.hs:3:9: error: parse error on input ‘using’
   |
 3 | class C using
   |         ^^^^^
 Failed, no modules loaded.
 Prelude>
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14642>
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