GHCi Package problem?

[Martin Erwig]

I encountered the following problem while loading a package,
and ghci (version 6.2) told me to report it to this list.

   Loading package fgl ... linking ...
   /usr/local/lib/ghc-6.2/HSfgl.o: unknown symbol 
`_DataziTree_flatten_entry'
   ghc-6.2: panic! (the `impossible' happened, GHC version 6.2):
           can't load package `fgl'

   Please report it as a compiler bug to 
glasgow-haskell-bugs at haskell.org,
   or http://sourceforge.net/projects/ghc/.

This happened after I removed "base" from the package_deps entry (see 
below).

Package {
   name = "fgl",
   auto = True,
   import_dirs = ["$libdir/imports"],
   source_dirs = [],
   library_dirs = ["$libdir"],
   hs_libraries = ["HSfgl"],
   extra_libraries = [],
   include_dirs = [],
   c_includes = [],
   package_deps = ["base"],
   extra_ghc_opts = ["-fglasgow-exts"],
   extra_cc_opts = [],
   extra_ld_opts = [],
   framework_dirs = [],
   extra_frameworks = []
}

When "base" is included, ghci start fine:

   Loading package base ... linking ... done.
   Loading package fgl ... linking ... done.
   Prelude>

I can even access some values:

   Prelude> Data.Graph.Inductive.version

   FGL - Functional Graph Library, February 2005

However, when I try others, I get errors:

   Prelude> Data.Graph.Inductive.Example.clr486

   GHCi runtime linker: fatal error: I found a duplicate definition for 
symbol
      _DataziGraphziInductiveziInternalziFiniteMap_Empty_closure
   whilst processing object file
      ./Data/Graph/Inductive/Internal/FiniteMap.o
   This could be caused by:
      * Loading two different object files which export the same symbol
      * Specifying the same object file twice on the GHCi command line
      * An incorrect `package.conf' entry, causing some object to be
        loaded twice.
   GHCi cannot safely continue in this situation.  Exiting now.  Sorry.


I don't know what to do about this.


--
Martin