id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
6029	GHC fails to stop at phase HCc	liuexp		"I tried with several different haskell source code and all got the same error:

[liuexp@liuexp pearls]$ ghc -C minfree.hs

addFlag by -C on the commandline:
    Warning: The -fvia-C flag does nothing; it will be removed in a future GHC release
ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for i386-unknown-linux):
	pipeLoop: at phase As but I wanted to stop at phase HCc



here's minfree.hs for reference:

[liuexp@liuexp pearls]$ cat minfree.hs
{-# OPTIONS_GHC -O2 #-}
module Pearls where
import Data.List hiding (union)
import Data.List.Ordered (minus,union)
import Data.Map (Map)
import Data.Set (Set)
import qualified Data.Set as DS
import qualified Data.Map as DM
import Data.Sequence (Seq, (<|), (|>), (><))
import qualified Data.Sequence as S
import qualified Data.Foldable as F

import Control.Monad
import Control.Applicative

--assuming no duplicates
minfree xs = minfrom 0 (length xs,xs)
minfrom a (n,xs)
	|n == 0 = a
	|m == b -a = minfrom b (n-m,vs)
	|otherwise = minfrom a (m,us)
	where 	(us,vs)= partition (<b) xs
		b = a + 1 + n `div` 2
		m = length us
"	bug	closed	normal		Compiler	7.4.1	duplicate			Unknown/Multiple	Unknown/Multiple	Other