[bug#50475] [PATCH] etc: committer: Amend previous commit if a copyright line was added.

[Xinglu Chen <public@yoctocell.xyz>]

Previously, the script would raise an error if a copyright line was added to a
file in gnu/packages/.  With this change, it will amend the previous commit
whenever a copyright line is added, and add the copyright line to the commit.

* etc/committer.scm.in (add-copyright-line): New procedure.
(main): Check if a copyright line was added and call ‘add-copyright-line’ if
necessary.
---
Before, you would get an error when a copyright line was added.  This
might also make people think that the previous commits were not
successful, at least I did the first time this happened.

--8<---------------cut here---------------start------------->8---
$ ./etc/committer.scm
gnu: Add emacs-nasm-mode.

* gnu/packages/emacs-xyz.scm (emacs-nasm-mode): New variable.
[master bbe52033d7] gnu: Add emacs-nasm-mode.
 1 file changed, 23 insertions(+)
Backtrace:
           5 (primitive-load "/home/yoctocell/src/guix-local/./etc/committer.scm")
In srfi/srfi-1.scm:
    634:9  4 (for-each #<procedure 7f3a50ebece0 at ice-9/eval.scm:333:13 (a)> ((#f #f #<<hunk> fi…>)))
In ice-9/eval.scm:
    619:8  3 (_ #(#(#(#(#(#(#(#(#(#<directory (guile-user) 7f3a53a87c80> #) (…)) #) #) …) #) …) #) #))
    619:8  2 (_ #(#(#(#<directory (guile-user) 7f3a53a87c80>) "gnu/packages/emacs-xyz.scm" #f #f …) …))
   626:19  1 (_ #(#(#(#<directory (guile-user) 7f3a53a87c80>) "gnu/packages/emacs-xyz.scm" #f #f …) …))
In unknown file:
           0 (cadr #f)

ERROR: In procedure cadr:
In procedure cadr: Wrong type (expecting pair): #f
--8<---------------cut here---------------end--------------->8---

With the patch, you get

--8<---------------cut here---------------start------------->8---
$ ./etc/committer.scm
gnu: Add emacs-nasm-mode.

* gnu/packages/emacs-xyz.scm (emacs-nasm-mode): New variable.
[master d662741368] gnu: Add emacs-nasm-mode.
 1 file changed, 23 insertions(+)
Amend and add copyright line for Xinglu Chen <public@yoctocell.xyz>

[master 024095ccd6] gnu: Add emacs-nasm-mode.
 Date: Wed Sep 8 15:39:12 2021 +0200
 1 file changed, 24 insertions(+)
--8<---------------cut here---------------end--------------->8---

 etc/committer.scm.in | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/etc/committer.scm.in b/etc/committer.scm.in
index e81ce16611..1ad83e37d7 100755
--- a/etc/committer.scm.in
+++ b/etc/committer.scm.in
@@ -5,6 +5,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2020, 2021 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2021 Sarah Morgensen <iskarian@mgsn.dev>
+;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -288,6 +289,15 @@ ChangeLog entry."
             (break-string-with-newlines message/f 72)
             (break-string-with-newlines changelog/f 72))))
 
+(define (add-copyright-line line)
+  "Add the copyright line on LINE to the previous commit."
+  (let ((author (match:substring
+                 (string-match "^\\+;;; Copyright ©[^[:alpha:]]+(.*)$" line)
+                 1)))
+    (format
+     (current-output-port) "Amend and add copyright line for ~a~%" author)
+    (system* "git" "commit" "--amend" "--no-edit")))
+
 (define (group-hunks-by-sexp hunks)
   "Return a list of pairs associating all hunks with the S-expression they are
 modifying."
@@ -370,15 +380,23 @@ modifying."
                                     (error "Cannot apply")))
                                 (usleep %delay))
                               hunks)
-                    (change-commit-message* (hunk-file-name (first hunks))
-                                            old new)
-                    (let ((port (open-pipe* OPEN_WRITE "git" "commit" "-F" "-")))
+                    (define copyright-line
+                      (any (lambda (line) (and=> (string-prefix? "+;;; Copyright ©" line)
+                                              (const line)))
+                                (hunk-diff-lines (first hunks))))
+                    (cond
+                     (copyright-line
+                      (add-copyright-line copyright-line))
+                     (else
+                      (let ((port (open-pipe* OPEN_WRITE "git" "commit" "-F" "-")))
+                        (change-commit-message* (hunk-file-name (first hunks))
+                                                old new)
                       (change-commit-message* (hunk-file-name (first hunks))
                                               old new
                                               port)
                       (usleep %delay)
                       (unless (eqv? 0 (status:exit-val (close-pipe port)))
-                        (error "Cannot commit")))))
+                        (error "Cannot commit")))))))
                  ;; XXX: we recompute the hunks here because previous
                  ;; insertions lead to offsets.
                  (new+old+hunks (diff-info)))))))

base-commit: 5c5e9d4e50af20042947b6b55e462a25b9d8cfc7
-- 
2.33.0