[Rd] Code tools for identifying which package A functions package B use?

[Henrik Bengtsson]

Hi,

I'd like to list all package PkgA functions that another package PkgB
use via Depends or Imports (ignoring Suggests for simplicity).  As
long as PkgB uses importFrom("PkgA", ...) it's just a matter of
parsing the NAMESPACE file or inspecting
asNamespace("PkgB")$.__NAMESPACE__.$imports.  However, what can be
done in case PkgB uses import("PkgA")?  Is there a function/package
already available for this?

Thanks,

Henrik