Text.ParserCombinators.Parsec requires -package text.

[Claus Reinke]

>Just to expand on this a little: it's not clear that we could do this
>even if we wanted to.  Given an arbitrary .o file, we can't tell (a) if
>it is a compiled Haskell module and (b) if so, where its .hi file can be
>found.  We can make guesses, but there isn't a general solution.

the only .o files you're interested in are those you've created, no?

so you could add that information to the .o file - but the .hi file might
have disappeared.  however, the original question was about finding 
required packages in the linking step, with only some .o file at hand.

so you could add info about required packages in the object file,
say as the value of some hidden default symbol, or as an unresolved
reference to a hidden symbol provided by the package. if, in the first
case, the <GHCrequired_packages> symbol doesn't exist or if, in the 
second case, there's no reference to a <GHCprovides_package_P> 
symbol, you know its not one of your object files, so it shouldn't
depend on your packages, should it?

just trying to understand the problem,
claus