#3888: Suggest -XGeneralizedNewtypeDeriving for newtypes
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Reporter: guest | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.12.1 | Keywords:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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newtype A = A Int deriving Enum
t.hs:1:27:
Can't make a derived instance of `Enum A'
(`A' has non-nullary constructors)
In the newtype declaration for `A'
But perhaps -XGeneralizedNewtypeDeriving should be suggested (ideally only
if the wrapped type actually had such an instance)?
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3888>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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