[GHC] #13223: Core Prep sometimes generates case of type lambda

[GHC]

#13223: Core Prep sometimes generates case of type lambda
-------------------------------------+-------------------------------------
           Reporter:  lukemaurer     |             Owner:  lukemaurer
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.1
           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:
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 Found something odd when updating the test case for T13156: Core Prep will
 turn

 {{{
 let f = \@a -> case ...
 in case f @ Any of ...
 }}}

 into

 {{{
 case (\@a -> case ...) of f { __DEFAULT ->
 case f @ Any of ...
 }}}

 because `f` is demanded and not an HNF. Seems like this is turning a lazy
 binding into a strict one since that \@a is about to be erased, but I
 haven't investigated.

 (Assigning to myself to put together a proper test case at least.)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13223>
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