From: Jeff King <peff@peff.net>
Date: Sat, 25 Apr 2026 23:47:00 GMT
Subject: Re: [PATCH] alias: restore support for simple dotted aliases
Message-ID: <20260425234700.GB29816@coredump.intra.peff.net>
In-Reply-To: <20260425232916.GA29816@coredump.intra.peff.net>

On Sat, Apr 25, 2026 at 07:29:16PM -0400, Jeff King wrote:

> On Sat, Apr 25, 2026 at 11:57:24AM +0200, Jonatan Holmgren wrote:
> 
> > That is a challenge we are going to have to consider. I think reserving
> > `command` is a worthwhile compromise, but obviously we cannot do that for
> > arbitrary future keys such as `help`, `hidden`, etc.
> 
> We don't necessarily have to reserve them. When we see alias.foo.bar, we
> could consider it as both alias "foo.bar" and the "bar" key of alias
> "foo", without regard to what is in "bar" (i.e., whether it is "command"
> or "help", etc). I.e., don't "fall back" but allow two overlapping
> namespace.s
> 
> That is the most backwards-compatible thing we could do, but does create
> some interesting situations.

For reference, I mean something like this:

diff --git a/alias.c b/alias.c
index ec9833dd30..07c6bd3645 100644
--- a/alias.c
+++ b/alias.c
@@ -34,16 +34,20 @@ static int config_alias_cb(const char *var, const char *value,
 	if (subsection && !subsection_len)
 		subsection = NULL;
 
-	if (subsection && strcmp(key, "command"))
-		return 0;
-
 	if (data->alias) {
 		int match;
 
 		if (subsection)
-			match = (strlen(data->alias) == subsection_len &&
-				 !strncmp(data->alias, subsection,
-					  subsection_len));
+			/*
+			 * alias.foo.command always matches "foo", but for
+			 * historical compatibility also match alias.foo.bar as
+			 * "foo.bar", even when "bar" is "command" or any other
+			 * key we happen to know about.
+			 */
+			match = (!strcmp(key, "command") &&
+				 strlen(data->alias) == subsection_len &&
+				 !strncmp(data->alias, subsection, subsection_len))
+				|| !strcmp(data->alias, subsection);
 		else
 			match = !strcasecmp(data->alias, key);
 
@@ -59,8 +63,23 @@ static int config_alias_cb(const char *var, const char *value,
 			return config_error_nonbool(var);
 
 		if (subsection)
+			/*
+			 * If it's not alias.foo.command, then either it's a
+			 * historical alias (git "foo.bar"), or it's some
+			 * metadata not support yet by this version
+			 * ("alias.foo.help" or similar).
+			 *
+			 * We'll guess it's the former and include the whole
+			 * "foo.bar" in the list.
+			 *
+			 * We might want to suppress duplicates when we see both
+			 * alias.foo.command and alias.foo.help, since that's
+			 * what a hypothetical future version might understand.
+			 */
 			item = string_list_append_nodup(data->list,
-				xmemdupz(subsection, subsection_len));
+							!strcmp(key, "command")
+							? xmemdupz(subsection, subsection_len)
+							: xstrdup(subsection));
 		else
 			item = string_list_append(data->list, key);
 		item->util = xstrdup(value);

-Peff