id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
3850	EmptyDataDecls and type context	Paczesiowa	igloo	"the following code fails to parse correctly or typecheck under 6.12.1


{{{
{-# LANGUAGE EmptyDataDecls #-}
data Show a => Foo a
}}}


error:


{{{
    No context is allowed on a GADT-style data declaration
    (You can put a context on each contructor, though.)
}}}


it works with 6.10.

this is the reason of HList failure on 6.12."	merge	closed	normal		Compiler	6.12.1	fixed	emptydatadecls		Unknown/Multiple	Unknown/Multiple	GHC rejects valid program