I think your incantation is incorrect: you build foobar@9.0.1, and you replace the source of foobar@9.5.0 only.

For the rest of your question, I think there is actually no way to fix that: when you use ",version", it gets evaluated before you can import the package. Maybe (package-version this-package) would work?

Le 20 octobre 2021 05:18:02 GMT-04:00, Phil Beadling <phil@beadling.co.uk> a écrit :
>Hi all,
>
>I'm using the following incantation:
>
>guix build
>--with-source=foobar@9.5.0=/opt/thirdparty/foobar/foobar950_beta/linux64
><--with-source=gurobipy@9.5.0=/opt/thirdparty/gurobi/gurobi950_beta/linux64>
>foobar
>
>
>However the package build is failing with:
>
>(copy-file "lib/libfoobar.so.9.0.1" "/gnu/store/gkawzac…")
>
>In procedure copy-file: No such file or directory
>
>
>That is the new version number 9.5.0 is not written to every place when
>transforming the original package (version 9.0.1).  I think only the
>package-version is updated, but the other package components are not then
>regenerated, meaning that if they use the package-version as an input we
>get a disjoint package.
>
>In the example above I use version like so:
>
>
>
>
>
>
>*(add-after 'install 'install-foobar-library
>      (lambda* (#:key outputs #:allow-other-keys)
>              (let* ((dir (string-append (assoc-ref outputs "out")
>
>"/lib/python3.8/site-packages/foobar/"))
>                                             (lib-to-install (string-append
>"libfoobar.so." ,version))*
>
>But ",version" is not updated, nor is it updated if I change this to call
>(package-version foobar).
>
>
>If I drop into Guile I can see this a bit more clearly by writing a
>manifest - the code below gives exactly the same error however when the
>package-version is displayed it correctly responds with 9.5.0.
>
>Not sure if this should be considered a bug, or if there is a lazy way of
>evaluating version so avoid the problem - I think it's unexpected from a
>practicioners point of view as packages end up inconsistent.
>
>I presume I can manually replace the arguments section of the package in
>the manifest to workaround this - is there a standard way of doing this?
>
>Any ideas or clarifications welcome!
>
>Cheers,
>Phil.
>
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>*(use-modules (guix transformations)             (guix packages))(define
>transform  ;; The package transformation procedure.
>(options->transformation   '((with-source .
>"gurobipy@9.5.0=/opt/thirdparty/foobar/foobar950_beta/linux64"))))(define
>my-package (transform (specification->package "foobar")))(display
>(package-version my-package)) ;; this will display version
>9.5.0(newline)(packages->manifest (list my-package)) ;; building this will
>fail because copy-file still looks for 9.0.1*