channels: Record 'guix' channel metadata in (guix config).

Partially fixes <https://bugs.gnu.org/45896>.

* guix/config.scm.in (%channel-metadata): New variable.
* guix/describe.scm (channel-metadata): Use it.
(current-channels): New procedure.
(current-profile-entries): Clarify docstring.
* guix/self.scm (compiled-guix): Add #:channel-metadata and pass it to
'make-config.scm'.
(make-config.scm): Add #:channel-metadata and define '%channel-metadata'
in the generated file.
(guix-derivation): Add #:channel-metadata and pass it to 'compiled-guix'.
* guix/channels.scm (build-from-source): Replace 'name', 'source', and
'commit' parameters with 'instance'.  Pass #:channel-metadata to BUILD.
(build-channel-instance): Adjust accordingly.
* build-aux/build-self.scm (build-program): Add #:channel-metadata
and pass it to 'guix-derivation'.
(build): Add #:channel-metadata and pass it to 'build-program'.
* guix/scripts/describe.scm (display-profile-info): Add optional
'channels' parameter.  Pass it to 'display-profile-content'.
(display-profile-content): Add optional 'channels' parameter and honor
it.  Iterate on CHANNELS rather than on the manifest entries of
PROFILE.
(guix-describe): When PROFILE is #f, call 'current-channels' and pass it
to 'display-profile-info', unless it returns the empty list.

1 files changed, 18 insertions, 12 deletions

diff --git a/guix/channels.scm b/guix/channels.scm
index e7e1eb6fd0..3cc3b4c438 100644
--- a/guix/channels.scm
+++ b/guix/channels.scm
@@ -626,16 +626,23 @@ that unconditionally resumes the continuation."
       (values (run-with-store store mvalue)
               store))))
 
-(define* (build-from-source name source
-                            #:key core verbose? commit
-                            (dependencies '()))
-  "Return a derivation to build Guix from SOURCE, using the self-build script
-contained therein; use COMMIT as the version string.  When CORE is true, build
-package modules under SOURCE using CORE, an instance of Guix."
+(define* (build-from-source instance
+                            #:key core verbose? (dependencies '()))
+  "Return a derivation to build Guix from INSTANCE, using the self-build
+script contained therein.  When CORE is true, build package modules under
+SOURCE using CORE, an instance of Guix."
+  (define name
+    (symbol->string
+     (channel-name (channel-instance-channel instance))))
+  (define source
+    (channel-instance-checkout instance))
+  (define commit
+    (channel-instance-commit instance))
+
   ;; Running the self-build script makes it easier to update the build
   ;; procedure: the self-build script of the Guix-to-be-installed contains the
   ;; right dependencies, build procedure, etc., which the Guix-in-use may not
-  ;; be know.
+  ;; know.
   (define script
     (string-append source "/" %self-build-file))
 
@@ -661,7 +668,9 @@ package modules under SOURCE using CORE, an instance of Guix."
           ;; cause us to redo half of the BUILD computation several times just
           ;; to realize it gives the same result.
           (with-trivial-build-handler
-           (build source #:verbose? verbose? #:version commit
+           (build source
+                  #:verbose? verbose? #:version commit
+                  #:channel-metadata (channel-instance->sexp instance)
                   #:pull-version %pull-version))))
 
       ;; Build a set of modules that extend Guix using the standard method.
@@ -672,10 +681,7 @@ package modules under SOURCE using CORE, an instance of Guix."
   "Return, as a monadic value, the derivation for INSTANCE, a channel
 instance.  DEPENDENCIES is a list of extensions providing Guile modules that
 INSTANCE depends on."
-  (build-from-source (symbol->string
-                      (channel-name (channel-instance-channel instance)))
-                     (channel-instance-checkout instance)
-                     #:commit (channel-instance-commit instance)
+  (build-from-source instance
                      #:core core
                      #:dependencies dependencies))