id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
5968	"GHC Panic: ""AThing evaluated unexpectedly"""	goldfire		"Using an unmodified build from March 13, 2012, I compiled the following:

{{{
{-# LANGUAGE TemplateHaskell #-}
data Bar a = Bar $( [t| a |] )
}}}

I got the following panic:

{{{
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 7.5.20120313 for x86_64-unknown-linux):
        AThing evaluated unexpectedly tcTyVar a{tv aKM}
}}}

I observed this exact same panic on a modified 3/25/12 build."	bug	closed	normal		Template Haskell	7.5	fixed	TemplateHaskell		Unknown/Multiple	Unknown/Multiple	None/Unknown	Unknown	th/T5968