Experimenting with GHC plugins. Trying to make an qualified name for (later) use in generated Core code.

The simple plugin is defined in src/PluginImportId/Plugin.hs and a test module in TestImportId.hs. To test,

ghc -package ghc -fplugin PluginImportId.Plugin TestImportId.hs

The result I get (with GHC 7.6.3):

[1 of 1] Compiling TestImportId     ( TestImportId.hs, TestImportId.o )
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
...
Loading package ghc-7.6.3 ... linking ... done.
Loading package plugin-import-id-0.1 ... linking ... done.
ghc: panic! (the 'impossible' happened)
  (GHC version 7.6.3 for x86_64-apple-darwin):
        mkPrelName: Didn't find id

I get the same failure with GHC 7.4.2.

What's going wrong?