[GHC] #11390: GHC does not warn about redundant patterns

[GHC]

#11390: GHC does not warn about redundant patterns
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        Reporter:  Iceland_jack      |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:  warnings
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by rwbarton):

 Empty data declarations are Haskell 2010, so it doesn't seem reasonable to
 give a warning that suggests something outside the Haskell 2010 language.
 If EmptyCase is already on, though, it could make sense to issue a warning
 in your second example.

 I don't understand your first example. Isn't the clause `sillyId x = case
 x of {}` just as "redundant" as the clause `sillyId x = x` was in the
 first place?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11390#comment:3>
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