GHCi and Unboxed tuples

[Mike Gunter]

I just finished tracking down the source of the following error from
GHCi:

  ghc-6.2: panic! (the `impossible' happened, GHC version 6.2):
           Bytecode generator can't handle unboxed tuples.  Possibly due
           to foreign import/export decls in source.  Workaround:
           compile this module to a .o file, then restart session.

Some clue to the source of the problem would be quite helpful.  (I
expect just about anything to at least be sometime useful -- even if
it's the low-level input to bytecode generator.)

It turns out the source of the problem is a definition in an imported
.hi file.  Would it be possible for GHCi to prune the inlined
definitions containing unboxed tuples and use the non-inlined ones?
(Are the non-inline definitions are in the object file?  "nm" suggests
they are.)

The best fix, of course, would be to make the bytecode generator
handle unboxed tuples.

        thanks,
        mike