[PATCH 2/3] alias: prepare for subsection aliases

[Jonatan Holmgren <jonatan@jontes.page>]

Switch git_unknown_cmd_config() from skip_prefix() to
parse_config_key() for alias parsing. This properly handles the
three-level config key structure and prepares for the new
alias.*.command subsection syntax in the next commit.

This is a compatibility break: the alias configuration parser used
to be overly permissive and accepted "alias.<subsection>.<key>" as
defining an alias "<subsection>.<key>". With this change,
alias.<subsection>.<key> entries are silently ignored (unless <key>
is "command", which will be given meaning in the next commit).

This behavior was arguably a bug, since config subsections were never
intended to work this way for aliases, and aliases with dots in their
names have never been documented or intentionally supported.

Signed-off-by: Jonatan Holmgren <jonatan@jontes.page>
---
 help.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/help.c b/help.c
index 0bdb7ca10f..eccd0c22f8 100644
--- a/help.c
+++ b/help.c
@@ -573,7 +573,8 @@ static int git_unknown_cmd_config(const char *var, const char *value,
 				  void *cb)
 {
 	struct help_unknown_cmd_config *cfg = cb;
-	const char *p;
+	const char *subsection, *key;
+	size_t subsection_len;
 
 	if (!strcmp(var, "help.autocorrect")) {
 		int v = parse_autocorrect(value);
@@ -588,8 +589,11 @@ static int git_unknown_cmd_config(const char *var, const char *value,
 	}
 
 	/* Also use aliases for command lookup */
-	if (skip_prefix(var, "alias.", &p))
-		add_cmdname(&cfg->aliases, p, strlen(p));
+	if (!parse_config_key(var, "alias", &subsection, &subsection_len,
+			      &key)) {
+		if (!subsection)
+			add_cmdname(&cfg->aliases, key, strlen(key));
+	}
 
 	return 0;
 }
-- 
2.53.0