id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
1001	"""ghc-6.6: panic! (the 'impossible' happened) interactiveUI:flush"" when hiding haskell98 and importing IO"	benjamin.franksen@…	igloo	"I was trying to compile John Macheam's ""GetOptions"" with ghc-6.6. It failed saying


{{{
ben@sarun: .../repos/GetOptions > runhaskell Setup.hs build    
Preprocessing library GetOptions-1.0...
Building GetOptions-1.0...

GetOptions.hs:31:7:
    Could not find module `IO':
      it is a member of package haskell98, which is hidden
}}}

I exposed haskell98:

{{{
ben@sarun: .../repos/GetOptions > sudo ghc-pkg expose haskell98
Saving old package config file... done.
Writing new package config file... done.
}}}

But still no luck... Anyway then I said to myself ""forget it, just use the hierarchical library stuff"", hid haskell98 package again, and changed the import stuff a bit (see below). Result:

{{{
ben@sarun: .../repos/GetOptions > runhaskell Setup.hs build

<interactive>:1:84:
    Failed to load interface for `IO':
      it is a member of package haskell98, which is hidden
ghc-6.6: panic! (the 'impossible' happened)
  (GHC version 6.6 for x86_64-unknown-linux):
        interactiveUI:flush

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
}}}

This is the ""fix"" I applied:

{{{
ben@sarun: .../repos/GetOptions > darcs whatsnew
{
hunk ./GetOptions.hs 27
-import List
+import Data.List
hunk ./GetOptions.hs 30
-import System
-import IO
+import System.IO
+--import IO
}
}}}

Here is the repo I pulled from, so maybe you can reproduce the bug:

{{{
ben@sarun: .../repos/GetOptions > cat _darcs/prefs/defaultrepo 
http://repetae.net/john/repos/GetOptions
}}}

I could be that my ghc installation is completely screwed up but I wouldn't know how or why.

Ben"	bug	closed	normal	6.6.1	Compiler	6.6	fixed			Linux	x86_64 (amd64)		Unknown	ghci017