Hello,


The following code, when compiled with GHC 4.08.1 under an i586
Archictecute with Red Hat Linux 6.2 produces this error message:

============================================================
ERROR MESSAGE:

Compilation Dump for: /usr/local/lib/ghc-4.08.1/hsc /tmp/ghc1430.cpp 2>>
erros -fglasgow-exts -fignore-interface-pragmas -fomit-interface-pragmas
-fsimplify [ -fmax-simplifier-iterations4 ]  
-fwarn-overlapping-patterns -fwarn-missing-methods -fwarn-missing-fields
-fwarn-deprecations -fwarn-duplicate-exports -fhi-version=408 -static
"-himap=.%.hi:/usr/local/lib/ghc-4.08.1/imports/lang%.hi:/usr/local/lib/ghc-4.08.1/imports/lang%.hi:/usr/local/lib/ghc-4.08.1/imports/std%.hi"
"-himap-sep=:"     -hifile=/tmp/ghc1430.hi -olang=asm
-ofile=/tmp/ghc1430.s -F=/tmp/ghc1430_stb.c -FH=/tmp/ghc1430_stb.h +RTS
-H6000000 -K1000000


rename/RnEnv.lhs:238: Non-exhaustive patterns in function get_tycon_key

==============================================================
CODE THAT PRODUCES THE ERROR

module Foo where

import MutableArray
import ByteArray
import ST
import PrelArrExtra

class Foo t where

     foo :: t -> ByteArray ix

instance Ix ix => Foo (forall s. MutableByteArray s ix) where

         foo x = runST(unsafeFreezeByteArray x)
  
================================================================


    I think this code is correct (???). The error message suggests a
compiler bug. Is this true ?
 

Heron de Carvalho

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