channels: Automatically add introduction for the official 'guix' channel.

This is useful when people run "guix time-machine -C channels.scm",
where 'channels.scm' misses channel introductions.

* guix/channels.scm (%default-channel-url): New variable.
(%default-channels): Use it.
(ensure-default-introduction): New procedure.
(latest-channel-instance): Call it.
This commit is contained in:
Ludovic Courtès 2020-06-08 22:22:36 +02:00
parent a941e8fe1f
commit c3f6f564e9
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GPG Key ID: 090B11993D9AEBB5

@ -148,18 +148,32 @@
"BBB0 2DDF 2CEA F6A8 0D1D E643 A2A0 6DF2 A33A 54FA")))
#f)) ;TODO: Add an intro signature so it can be exported.
(define %default-channel-url
;; URL of the default 'guix' channel.
"https://git.savannah.gnu.org/git/guix.git")
(define %default-channels
;; Default list of channels.
(list (channel
(name 'guix)
(branch "master")
(url "https://git.savannah.gnu.org/git/guix.git")
(url %default-channel-url)
(introduction %guix-channel-introduction))))
(define (guix-channel? channel)
"Return true if CHANNEL is the 'guix' channel."
(eq? 'guix (channel-name channel)))
(define (ensure-default-introduction chan)
"If CHAN represents the \"official\" 'guix' channel and lacks an
introduction, add it."
(if (and (guix-channel? chan)
(not (channel-introduction chan))
(string=? (channel-url chan) %default-channel-url))
(channel (inherit chan)
(introduction %guix-channel-introduction))
chan))
(define-record-type <channel-instance>
(channel-instance channel commit checkout)
channel-instance?
@ -385,7 +399,9 @@ their relation."
(and (string=? (basename file) ".git")
(eq? 'directory (stat:type stat))))
(let-values (((checkout commit relation)
(let-values (((channel)
(ensure-default-introduction channel))
((checkout commit relation)
(update-cached-checkout (channel-url channel)
#:ref (channel-reference channel)
#:starting-commit starting-commit)))