Suggest -XGeneralizedNewtypeDeriving (fix Trac #3888)
authorsimonpj@microsoft.com <unknown>
Mon, 1 Mar 2010 11:15:55 +0000 (11:15 +0000)
committersimonpj@microsoft.com <unknown>
Mon, 1 Mar 2010 11:15:55 +0000 (11:15 +0000)
commit88e7faf19b7bcfd8d0d41fa88029c048b615c432
tree3908aabf52db5bd314097256059835cffd769037
parent6d0b77ef003cc4add9a4252863a56416541e93a9
Suggest -XGeneralizedNewtypeDeriving (fix Trac #3888)

If we can't derive a type, but it's a reasonable possibility that
newtype deriving would do the job, suggest it.

A little refactoring too, moving non_iso_class to top level,
and putting it with std_class_via_iso.
compiler/typecheck/TcDeriv.lhs