Object I/O causes GHC panic

[Simon Peyton-Jones]

Excellent bug.  In an amazingly obscure situation, GHC managed to
filter out *all* the alternatives of a case expression, and was then
very surprised to find a case expression with no alternatives.

Now fixed.  You'll need to check out the source tree to get the fix.
As a workaround, you can probably compile that module without -O.

Thank you for finding this.

Simon

| -----Original Message-----
| From: Krasimir Angelov [mailto:ka2_mail at yahoo.com] 
| Sent: 13 February 2002 07:55
| To: glasgow-haskell-bugs at haskell.org
| Subject: Object I/O causes GHC panic
| 
| 
|       Hi
| 
|    The trouble is when uncomment lines 177-178 from 
| ObjectIO/WindowDispose.hs
| 
| For GHC-5.02.1
| -------------------------------------------------------
| ghc: panic! (the `impossible' happened, GHC version
| 5.02.1):
|         coreSyn/CoreUtils.lhs:98: Non-exhaustive
| patterns in function coreAltsTy
| pe
| 
| 
| Please report it as a compiler bug to 
| glasgow-haskell-bugs at haskell.org, or 
| http://sourceforge.net/projects/ghc/.
| 
| -------------------------------------------------------
| 
| For GHC-5.03 snapshot release
| -------------------------------------------------------
| ghc: panic! (the `impossible' happened, GHC version
| 5.03):
|         Prelude.head: empty list
| 
| Please report it as a compiler bug to 
| glasgow-haskell-bugs at haskell.org, or 
| http://sourceforge.net/projects/ghc/.
| 
| -------------------------------------------------------
| 
|     How can I avoid this error?
| 
| Thanks
| 
| __________________________________________________
| Do You Yahoo!?
| Send FREE Valentine eCards with Yahoo! Greetings! 
| http://greetings.yahoo.com 
| _______________________________________________
| Glasgow-haskell-bugs mailing list 
| Glasgow-haskell-bugs at haskell.org 
| http://www.haskell.org/mailman/listinfo/glasgow-| haskell-bugs
|