<<loop>>

[nobody]

ghc -c -fglasgow-exts Typedecl.hs  (and without flag)
ghc-5.00: panic! (the `impossible' happened, GHC
version 5.00):
        <<loop>>

Please report it as a compiler bug to
glasgow-haskell-bugs@haskell.org,
or http://sourceforge.net/projects/ghc/.


data Val      = .......
                    |  Fun (Val -> TM Val)
              

type TM a = EnvT
               ( ST1 Record
               ( ST3 String
               ( MaybeT
               ( IdM)))) a

[simonmar]

Logged In: YES 
user_id=48280

The code fragment you gave isn't complete enough for us to 
reproduce the bug.  Could you provide a complete self 
contained example?  (and don't forget to include your GHC 
version and platform info, and your email address.)  Thanks.

[aarchiba]

Logged In: YES 
user_id=180731

I have an example but it's huge (uses Parsec and a few of my
own files).  I can see if I can shrink it, or I can mail you
the whole mess; email me. 

Andrew

[aarchiba]

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user_id=180731

This bug can be triggered on GHC-5.00 by the following file:

$ cat >GHCbug.hs <<EOF
module GHCbug where
type A = B
data B = B (A->A)
EOF
$ ghc GHCbug.hs
ghc-5.00: panic! (the `impossible' happened, GHC version 5.00):
        <<loop>>
 
Please report it as a compiler bug to
glasgow-haskell-bugs@haskell.org,
or http://sourceforge.net/projects/ghc/.
$

If I delete the "type" and replace the Bs by As, the error
goes away, and GHCi loads it happily. If I replace the
"data" by a "type" GHC (correctly) reports an error in my
program.  If I replace it by a "newtype", I get the same
bug. Hugs likes this file fine. 

[simonmar]

Logged In: YES 
user_id=48280

Bug was fixed in GHC 5.00.1 (submitter was using 5.00).