Suggest -XGeneralizedNewtypeDeriving for newtypes
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)?
Trac metadata
Trac field | Value |
---|---|
Version | 6.12.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | vogt.adam@gmail.com |
Operating system | |
Architecture |