id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
5377,TypeSynonymInstances dysfunctional in ghc-7.2.1-rc1?,hvr,,"The following code causes GHC to suggest enabling the TypeSynonymInstances language extension:

{{{
#!hs
type Foo = Maybe Int

class Bar x where
  bar :: x -> ()
  bar _ = ()

instance Bar Int

instance Bar Foo
}}}

but adding a `{-# LANGUAGE TypeSynonymInstances #-}` doesn't suffice, as GHC then suggests enabling FlexibleInstances instead.

With ghc-7.0.4 the TypeSynonymInstances extension by itself was enough to make the code above compile. This breaks compilation for a few packages on hackage which assume that TypeSynonymInstances suffices.",bug,closed,normal,,Compiler,7.1,invalid,,,Linux,x86_64 (amd64),GHC rejects valid program,,,,,