[bug#47336] Disarchive as a fallback for downloads

[Timothy Sample <samplet@ngyro.com>]

reopen 47336
thanks

Hi again,

Timothy Sample <samplet@ngyro.com> writes:

> I just pushed this series [...]

And broke “guix pull”!!  (I somehow fooled myself into thinking that I
had already tested with “guix pull --url=...” locally.)  I reverted the
offending commit.

It turns out that adding a reference from “(guix build download)” to
“(guix swh)” breaks “compute-guix-derivation” in
“build-aux/build-self.scm”.  This is because “(guix swh)” references
“(json)”, which is not available in the “compute-guix-derivation”
environment.  I tried mimicking the “fake-git” trick, but it didn’t work
(I guess it needs the “define-json-mapping” macro at compile time).

Everything works if I remove the #:autoload for “(guix swh)” and put

  ;; If we import (guix swh) directly, we introduce a compile-time
  ;; dependency on Guile-JSON.  This breaks the "build-self" code, which
  ;; needs to build this module without Guile-JSON.  Hence, we track
  ;; down the following procedure at runtime.
  (define swh-download-directory
    (module-ref (resolve-module '(guix swh)) 'swh-download-directory))

inside of “disarchive-fetch/any” (just before it’s needed).  Does this
approach look okay?


-- Tim