[GHC] #445: panic! mkWWcpr: not a product

[GHC]

#445: panic! mkWWcpr: not a product
-----------------------+----------------------------------------------------
  Reporter:  nobody    |          Owner:  simonpj
      Type:  bug       |         Status:  new    
  Priority:  normal    |      Milestone:         
 Component:  Compiler  |        Version:  6.4    
  Severity:  normal    |     Resolution:  None   
  Keywords:            |             Os:  Unknown
Difficulty:  Unknown   |   Architecture:  Unknown
-----------------------+----------------------------------------------------
Changes (by guest):

  * architecture:  => Unknown
  * difficulty:  => Unknown
  * os:  => Unknown

Comment:

 I have the same problem with ghc 6.4.1.

 I was not using --make, but using -O2 -prof -auto-all.

 Here is the source:
 {{{
 module M where

 newtype T a = T { unT :: a }

 f = unT

 test cs = f $ case cs of
   [] -> T []
   (x:xs) -> T $ test cs
 }}}
 {{{
 $ ghc -c M.hs -O2 -prof -auto-all
 ghc-6.4.1: panic! (the `impossible' happened, GHC version 6.4.1):
     mkWWcpr: not a product [a{tv a19n}]

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

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/445>
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