Package version at build side

[Andreas Enge <andreas@enge.fr>]

Hello,

for kdelibs, I need to pass the version of the input docbook-xsl as
a configure flag. So I added something like

       #:configure-flags
        (list "-DCMAKE_VERBOSE_MAKEFILE=ON" ; for debugging
              (let ((docbook-xsl (assoc-ref %build-inputs "docbook-xsl")))
                (string-append "-DDOCBOOKXSL_DIR="
                               docbook-xsl
                               "/xml/xsl/docbook-xsl-"
                               (package-version docbook-xsl)
                               "/")))

Now package-version seems to be defined in (guix package); when I add this as
modules, more and more of them are pulled in. Currently I have

       #:modules ((guix packages) ; for PACKAGE-VERSION
                  (guix base32)
                  (guix config)
                  (guix derivations)
                  (guix records)
                  (guix serialization)
                  (guix store)
                  (guix utils)
                  (guix build syscalls)
                  (guix build utils))
       #:imported-modules ((guix packages)
                           (guix base32)
                           (guix config)
                           (guix derivations)
                           (guix records)
                           (guix serialization)
                           (guix store)
                           (guix utils)
                           (guix build syscalls)
                           (guix build utils))

When I "make" and "./pre-inst-env guix build kdelibs", I get
ice-9/boot-9.scm:106:20: no code for module (guix hash)

So I add (guix hash), and then I get "no code for module (guix ...)"
and so on, probably until all of guix is in my package.

Is there a simpler solution?

Andreas