shortlog: remove unused(?) "repo-abbrev" feature

Remove support for the magical "repo-abbrev" comment in .mailmap
files. This was added to .mailmap parsing in [1], as a generalized
feature of the git-shortlog Perl script added earlier in [2].

There was no documentation or tests for this feature, and I don't
think it's used in practice anymore.

What it did was to allow you to specify a single string to be
search-replaced with "/.../" in the .mailmap file. E.g. for
linux.git's current .mailmap:

    git archive --remote=git@gitlab.com:linux-kernel/linux.git \
        HEAD -- .mailmap | grep -a repo-abbrev
    # repo-abbrev: /pub/scm/linux/kernel/git/

Then when running e.g.:

    git shortlog --merges --author=Linus -1 v5.10-rc7..v5.10 | grep Merge

We'd emit (the [...] is mine):

      Merge tag [...]git://git.kernel.org/.../tip/tip

But will now emit:

      Merge tag [...]git.kernel.org/pub/scm/linux/kernel/git/tip/tip

I think at this point this is just a historical artifact we can get
rid of. It was initially meant for Linus's own use when we integrated
the Perl script[2], but since then it seems he's stopped using it.

Digging through Linus's release announcements on the LKML[3] the last
release I can find that made use of this output is Linux 2.6.25-rc6
back in March 2008[4]. Later on Linus started using --no-merges[5],
and nowadays seems to prefer some custom not-quite-shortlog format of
merges from lieutenants[6].

You will still see it on linux.git if you run "git shortlog" manually
yourself with --merges, with this removed you can still get the same
output with:

    git log --pretty=fuller v5.10-rc7..v5.10 |
    sed 's!/pub/scm/linux/kernel/git/!/.../!g' |
    git shortlog

Arguably we should do the same for the search-replacing of "[PATCH]"
at the beginning with "". That seems to be another relic of a bygone
era when linux.git patches would have their E-Mail subject lines
applied as-is by "git am" or whatever. But we documented that feature
in "git-shortlog(1)", and it seems more widely applicable than
something purely kernel-specific.

1. 7595e2ee6ef (git-shortlog: make common repository prefix
   configurable with .mailmap, 2006-11-25)
2. fa375c7f1b6 (Add git-shortlog perl script, 2005-06-04)
3. https://lore.kernel.org/lkml/
4. https://lore.kernel.org/lkml/alpine.LFD.1.00.0803161651350.3020@woody.linux-foundation.org/
5. https://lore.kernel.org/lkml/BANLkTinrbh7Xi27an3uY7pDWrNKhJRYmEA@mail.gmail.com/
6. https://lore.kernel.org/lkml/CAHk-=wg1+kf1AVzXA-RQX0zjM6t9J2Kay9xyuNqcFHWV-y5ZYw@mail.gmail.com/

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 13 insertions, 35 deletions

diff --git a/mailmap.c b/mailmap.c
index 962fd86d6d..eb77c6e77c 100644
--- a/mailmap.c
+++ b/mailmap.c
@@ -143,31 +143,13 @@ static char *parse_name_and_email(char *buffer, char **name,
 	return (*right == '\0' ? NULL : right);
 }
 
-static void read_mailmap_line(struct string_list *map, char *buffer,
-			      char **repo_abbrev)
+static void read_mailmap_line(struct string_list *map, char *buffer)
 {
 	char *name1 = NULL, *email1 = NULL, *name2 = NULL, *email2 = NULL;
-	if (buffer[0] == '#') {
-		static const char abbrev[] = "# repo-abbrev:";
-		int abblen = sizeof(abbrev) - 1;
-		int len = strlen(buffer);
 
-		if (!repo_abbrev)
-			return;
-
-		if (len && buffer[len - 1] == '\n')
-			buffer[--len] = 0;
-		if (!strncmp(buffer, abbrev, abblen)) {
-			char *cp;
-
-			free(*repo_abbrev);
-
-			for (cp = buffer + abblen; isspace(*cp); cp++)
-				; /* nothing */
-			*repo_abbrev = xstrdup(cp);
-		}
+	if (buffer[0] == '#')
 		return;
-	}
+
 	if ((name2 = parse_name_and_email(buffer, &name1, &email1, 0)) != NULL)
 		parse_name_and_email(name2, &name2, &email2, 1);
 
@@ -175,8 +157,7 @@ static void read_mailmap_line(struct string_list *map, char *buffer,
 		add_mapping(map, name1, email1, name2, email2);
 }
 
-static int read_mailmap_file(struct string_list *map, const char *filename,
-			     char **repo_abbrev)
+static int read_mailmap_file(struct string_list *map, const char *filename)
 {
 	char buffer[1024];
 	FILE *f;
@@ -192,13 +173,12 @@ static int read_mailmap_file(struct string_list *map, const char *filename,
 	}
 
 	while (fgets(buffer, sizeof(buffer), f) != NULL)
-		read_mailmap_line(map, buffer, repo_abbrev);
+		read_mailmap_line(map, buffer);
 	fclose(f);
 	return 0;
 }
 
-static void read_mailmap_string(struct string_list *map, char *buf,
-				char **repo_abbrev)
+static void read_mailmap_string(struct string_list *map, char *buf)
 {
 	while (*buf) {
 		char *end = strchrnul(buf, '\n');
@@ -206,14 +186,12 @@ static void read_mailmap_string(struct string_list *map, char *buf,
 		if (*end)
 			*end++ = '\0';
 
-		read_mailmap_line(map, buf, repo_abbrev);
+		read_mailmap_line(map, buf);
 		buf = end;
 	}
 }
 
-static int read_mailmap_blob(struct string_list *map,
-			     const char *name,
-			     char **repo_abbrev)
+static int read_mailmap_blob(struct string_list *map, const char *name)
 {
 	struct object_id oid;
 	char *buf;
@@ -231,13 +209,13 @@ static int read_mailmap_blob(struct string_list *map,
 	if (type != OBJ_BLOB)
 		return error("mailmap is not a blob: %s", name);
 
-	read_mailmap_string(map, buf, repo_abbrev);
+	read_mailmap_string(map, buf);
 
 	free(buf);
 	return 0;
 }
 
-int read_mailmap(struct string_list *map, char **repo_abbrev)
+int read_mailmap(struct string_list *map)
 {
 	int err = 0;
 
@@ -247,10 +225,10 @@ int read_mailmap(struct string_list *map, char **repo_abbrev)
 	if (!git_mailmap_blob && is_bare_repository())
 		git_mailmap_blob = "HEAD:.mailmap";
 
-	err |= read_mailmap_file(map, ".mailmap", repo_abbrev);
+	err |= read_mailmap_file(map, ".mailmap");
 	if (startup_info->have_repository)
-		err |= read_mailmap_blob(map, git_mailmap_blob, repo_abbrev);
-	err |= read_mailmap_file(map, git_mailmap_file, repo_abbrev);
+		err |= read_mailmap_blob(map, git_mailmap_blob);
+	err |= read_mailmap_file(map, git_mailmap_file);
 	return err;
 }