id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
3965	'deriving Data' compilation regression 6.10.1 -> 6.12.1	ronwalf		"Compiling the attached file in GHC 6.12.1 gives the following error, when GHC 6.10.1 compiles it fine:
{{{
[1 of 1] Compiling Main             ( baddata.hs, baddata.o )

baddata.hs:33:14:
    No instances for (Data Const, Data Var)
      arising from the 'deriving' clause of a data type declaration
                   at baddata.hs:33:14-17
    Possible fix:
      add an instance declaration for (Data Const, Data Var)
      or use a standalone 'deriving instance' declaration instead,
         so you can specify the instance context yourself
    When deriving the instance for (Data (Domain e g))
}}}
"	bug	closed	high	6.12.3	Compiler	6.12.1	fixed			MacOS X	x86	GHC rejects valid program		deriving/should_compile/T3965