[GHC] #15289: isUnliftedType GHC panic on pattern with True :: Maybe

[GHC]

#15289: isUnliftedType GHC panic on pattern with True :: Maybe
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        Reporter:  Remi              |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  low               |            Milestone:  8.6.1
       Component:  Compiler (Type    |              Version:  8.4.3
  checker)                           |             Keywords:
      Resolution:                    |  PatternSynonyms
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"2896082ec79f02b6388e038a8dae6cb22fe72dfc/ghc"
 2896082e/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="2896082ec79f02b6388e038a8dae6cb22fe72dfc"
 Fix error recovery for pattern synonyms

 As Trac #15289 showed, we were carrying on after a type error
 in a pattern synonym, and then crashing.  This patch improves
 error handling for pattern synonyms.

 I also moved a bit of code from TcBinds into TcPatSyn, which
 helpfully narrows the API.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15289#comment:5>
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