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