This program should eventually replace the lexically-based
tags program.  But before this can happen, several problems 
must be addressed:

  * Performance is disastrous: it takes much longer to run ghctags
    than it does to compile GHC

  * The program does not use the correct source-code locations

The program accepts both its own arguments and options intended for GHC.
As a quick self-test, you can run

  ./ghctags -- -package ghc -- GhcTags.hs