<interactive>: internal error, ghc-6.0.1

[Simon Marlow]

> I suspect that may previous bug report on interactive interpreter 
> should be replaced with the following one, which is simple to 
> analyse.
> This is on
> 
>   ghc-6.0.1 
>   installed from RPM on  Red Hat Linux release 7.3 (Valhalla),
>   i-386 unknown.
> 
> Probably, you can reduce the example several times more.
> 
>   ghci Main +RTS -M1m -RTS
> 
>   ..> : Main
>   ..> main
>   ... 
>   (<interactive>: internal error: thread_stack: 
>   weird activation record found on stack: 1564
>   Please report this as a bug to glasgow-haskell-bugs at haskell.org ..
> 
> Probably, the interpreter manages memory in a wrong way.
> Can you reproduce the effect?

That's a bug, thanks for the report.

Just out of interest, why are you passing the -M1m flag to ghci?  This
sets a bound of 1M on GHC's memory, and causes the compacting GC to kick
in when this bound is approached (which will be almost immediately).
The bug was in the compacting garbage collector, which explains why it
hasn't shown up until now.

Cheers,
	Simon