[GHC] #14421: LambdaCase should be suggested if it is used but not enabled

[GHC]

#14421: LambdaCase should be suggested if it is used but not enabled
-------------------------------------+-------------------------------------
        Reporter:  tomjaguarpaw      |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4260
       Wiki Page:                    |
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Changes (by sighingnow):

 * status:  new => closed
 * differential:   => Phab:D4260
 * resolution:   => fixed


Comment:

 This ticket has already implemented in the `BlockArguments` patch, which
 will be included in ghc-8.6.1. With ghc-HEAD, you will get:

 {{{#!hs
 Prelude> :t \case (_,_) -> ()

 <interactive>:1:2: error: Illegal lambda-case (use -XLambdaCase)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14421#comment:1>
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