id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
3954	Contexts on empty data decls falsely rejected	ksf		"HList uses EmptyDataDecls and contains

{{{
data HNat x => Label x ns desc 
}}}

which fails with 

{{{ 
Data/HList/Label3.hs:37:0:
    No context is allowed on a GADT-style data declaration
    (You can put a context on each contructor, though.) 
}}}

, regressing from 6.10.

My crystal ball tells me someone has been simplifying the implementation of EmptyDataDecls to be GADTs without {{{where}}}, and missed the corner case."	bug	closed	normal		Compiler (Type checker)	6.12.1	duplicate			Unknown/Multiple	Unknown/Multiple	GHC rejects valid program