Re: Compiler Crash: ghc-2.05:panic! lookupBindC:no info!

[Simon L Peyton Jones]

> The following program (rather condensed as it comes from something
> much larger), crashes the compiler. I am using ghc-2.05 on a Solaris
> box, with one or two patches(including the WwLib one which Simon gave
> me, but this error occured before applying this patch).

Thanks for this bug report, and for localising it so well.  
It's easily fixed, I'm glad to say.
In
        ghc/compiler/simplCore/SimplCore.lhs

replace this equation of tidyCoreExpr.  The lines marked "!!" are the
changed ones.

Simon


 -- Eliminate polymorphic case, for which we can't generate code just yet
tidyCoreExpr (Case scrut (AlgAlts [] (BindDefault deflt_bndr rhs)))
  | not (typeOkForCase (idType deflt_bndr))
  = pprTrace "Warning: discarding polymorphic case:" (ppr PprDebug scrut) $
    case scrut of
!!      Var v -> lookupId v     `thenTM` \ v' ->
!!               extendEnvTM deflt_bndr v' (tidyCoreExpr rhs)
        other -> tidyCoreExpr (Let (NonRec deflt_bndr scrut) rhs)