GHC internal error

[Philip Weaver]

Yes, I can do that.  However, I'm hoping to narrow it down a lot more so
that I can file a more useful bug report.

Since sending my last email, I have learned a bit more:

I was using 'fail' (the Monad being ReaderT . StateT . ST) to report errors.
 If I replace 'fail msg' with 'error msg' or 'return (error msg)', then the
aforementioned internal error does not occur.

In some cases, the program dies with the aforementioned error.  In other
cases, it segfaults.

- Philip

On Mon, Apr 5, 2010 at 11:59 AM, Don Stewart <dons at galois.com> wrote:

> Any 'internal error' is almost certainly an RTS or compiler bug. Can you
> make a bug report?
>
>
> philip.weaver:
> > Hi all,
> >
> > A program that I built with GHC is crashing at runtime with the following
> > error:
> >
> >     internal error: eval_thunk_selector: strange selectee 12
> >
> > I have not found much via Google, just an old post regarding ghc 6.0 that
> > recommends cleaning and rebuilding.  I have cleaned the build directory
> and
> > re-built the executable, and I still get the error.
> >
> > The program is a compiler, and this error began showing up after I added
> > support for memoization of results using the ST Monad and STRefs.  For
> example,
> > the following function creates a reference to a thunk:
> >
> > newMutableRef m
> >   = do ref <- newSTRef $ error "access ref too soon!"
> >        let m' = do r <- m
> >                    writeSTRef ref (return r)
> >                    return r
> >        writeSTRef ref m'
> >        return $ ref
> >
> > Here's some information about my system:
> >
> >   • GHC 6.12.1
> >   • Mac OS X 10.6.3 (Snow Leopard)
> >
> > So, what could cause this error?  Any suggestions that can help me narrow
> down
> > the problem would be greatly appreciated.  If this is in fact a GHC bug,
> I'd
> > like to find a workaround for now and also reproduce it in a small
> example so I
> > can file a bug report.
> >
> > - Philip
> >
>
> > _______________________________________________
> > Glasgow-haskell-users mailing list
> > Glasgow-haskell-users at haskell.org
> > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
>
>
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