[RFC PATCH v2] remote: add --save-push option to git remote set-url

[Denton Liu <liu.denton@gmail.com>]

This adds the --save-push option to `git remote set-url` such that when
executed, we move the remote.*.url to remote.*.pushurl and set
remote.*.url to the given url argument.

For example, if we have the following config:

	[remote "origin"]
		url = git@github.com:git/git.git

`git remote set-url --save-push origin https://github.com/git/git.git`
would change the config to the following:

	[remote "origin"]
		url = https://github.com/git/git.git
		pushurl = git@github.com:git/git.git

Signed-off-by: Denton Liu <liu.denton@gmail.com>
---
I decided to address your comments and reroll the patch one more time. 

Even though the option isn't _that_ commonly used, I've managed to use
it a couple of times since I've implemented so I believe that this
option should be included.

---
 Documentation/git-remote.txt |  5 +++++
 builtin/remote.c             | 25 ++++++++++++++++++++-----
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-remote.txt b/Documentation/git-remote.txt
index 0cad37fb81..8ce85fe2f2 100644
--- a/Documentation/git-remote.txt
+++ b/Documentation/git-remote.txt
@@ -19,6 +19,7 @@ SYNOPSIS
 'git remote set-url' [--push] <name> <newurl> [<oldurl>]
 'git remote set-url --add' [--push] <name> <newurl>
 'git remote set-url --delete' [--push] <name> <url>
+'git remote set-url --save-push' <name> <url>
 'git remote' [-v | --verbose] 'show' [-n] <name>...
 'git remote prune' [-n | --dry-run] <name>...
 'git remote' [-v | --verbose] 'update' [-p | --prune] [(<group> | <remote>)...]
@@ -155,6 +156,10 @@ With `--delete`, instead of changing existing URLs, all URLs matching
 regex <url> are deleted for remote <name>.  Trying to delete all
 non-push URLs is an error.
 +
+With `--save-push`, the current URL is saved into the push URL before setting
+the URL to <url>. Note that this command will not work if more than one URL is
+defined or if any push URLs are defined because behavior would be ambiguous.
++
 Note that the push URL and the fetch URL, even though they can
 be set differently, must still refer to the same place.  What you
 pushed to the push URL should be what you would see if you
diff --git a/builtin/remote.c b/builtin/remote.c
index f7edf7f2cb..0eaec7ef38 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -24,8 +24,9 @@ static const char * const builtin_remote_usage[] = {
 	N_("git remote set-branches [--add] <name> <branch>..."),
 	N_("git remote get-url [--push] [--all] <name>"),
 	N_("git remote set-url [--push] <name> <newurl> [<oldurl>]"),
-	N_("git remote set-url --add <name> <newurl>"),
-	N_("git remote set-url --delete <name> <url>"),
+	N_("git remote set-url --add [--push] <name> <newurl>"),
+	N_("git remote set-url --delete [--push] <name> <url>"),
+	N_("git remote set-url --save-push <name> <url>"),
 	NULL
 };
 
@@ -77,8 +78,9 @@ static const char * const builtin_remote_geturl_usage[] = {
 
 static const char * const builtin_remote_seturl_usage[] = {
 	N_("git remote set-url [--push] <name> <newurl> [<oldurl>]"),
-	N_("git remote set-url --add <name> <newurl>"),
-	N_("git remote set-url --delete <name> <url>"),
+	N_("git remote set-url --add [--push] <name> <newurl>"),
+	N_("git remote set-url --delete [--push] <name> <url>"),
+	N_("git remote set-url --save-push <name> <url>"),
 	NULL
 };
 
@@ -1519,7 +1521,7 @@ static int get_url(int argc, const char **argv)
 
 static int set_url(int argc, const char **argv)
 {
-	int i, push_mode = 0, add_mode = 0, delete_mode = 0;
+	int i, push_mode = 0, save_push = 0, add_mode = 0, delete_mode = 0;
 	int matches = 0, negative_matches = 0;
 	const char *remotename = NULL;
 	const char *newurl = NULL;
@@ -1532,6 +1534,8 @@ static int set_url(int argc, const char **argv)
 	struct option options[] = {
 		OPT_BOOL('\0', "push", &push_mode,
 			 N_("manipulate push URLs")),
+		OPT_BOOL('\0', "save-push", &save_push,
+			 N_("change fetching URL behavior")),
 		OPT_BOOL('\0', "add", &add_mode,
 			 N_("add URL")),
 		OPT_BOOL('\0', "delete", &delete_mode,
@@ -1543,6 +1547,8 @@ static int set_url(int argc, const char **argv)
 
 	if (add_mode && delete_mode)
 		die(_("--add --delete doesn't make sense"));
+	if (save_push && (push_mode || add_mode || delete_mode))
+		die(_("--save-push cannot be used with other options"));
 
 	if (argc < 3 || argc > 4 || ((add_mode || delete_mode) && argc != 3))
 		usage_with_options(builtin_remote_seturl_usage, options);
@@ -1564,6 +1570,15 @@ static int set_url(int argc, const char **argv)
 		urlset = remote->pushurl;
 		urlset_nr = remote->pushurl_nr;
 	} else {
+		if (save_push) {
+			if (remote->url_nr != 1 || remote->pushurl_nr != 0)
+				die(_("--save-push can only be used when one url and no pushurl is defined"), remotename);
+
+			strbuf_addf(&name_buf, "remote.%s.pushurl", remotename);
+			git_config_set(name_buf.buf, remote->url[0]);
+			strbuf_reset(&name_buf);
+		}
+
 		strbuf_addf(&name_buf, "remote.%s.url", remotename);
 		urlset = remote->url;
 		urlset_nr = remote->url_nr;
-- 
2.19.1