[RFC PATCH] Allow aliases that include other aliases

[Tim Schumacher <timschumi@gmx.de>]

Aliases can only contain non-alias git commands and arguments,
but not other user-defined aliases. Resolving nested aliases
is prevented by breaking the loop after the first alias was
processed, git then fails with a command-not-found error.

Allow resolving nested aliases by not breaking the loop in
run_argv() after the first alias was processed. Instead, continue
incrementing done_alias until handle_alias() fails, which means
that there are no further aliases that can be processed.

---

I submitted this as RFC because I'm not sure whether disallowing
nested aliases was an intentional design choice. The done_alias
check implies that disallowing is intended, but the direct
recursion check for aliases that call themselves opposes that.

Furthermore, including this patch allows creating a looping state,
since the recursion check only checks if an alias is directly calling
itself.
One solution would be to break the loop as soon as done_alias reaches
a certain value, but that requires setting an arbitrary point of "too
many recursions".
A list of already resolved aliases and breaking the loop as soon as
an alias is resolved twice would probably do the trick, but
implementing that is well beyond the point of what I'm capable of
doing.

---
 git.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/git.c b/git.c
index c27c38738..9d3cf5797 100644
--- a/git.c
+++ b/git.c
@@ -695,11 +695,9 @@ static int run_argv(int *argcp, const char ***argv)
 		 * of overriding "git log" with "git show" by having
 		 * alias.log = show
 		 */
-		if (done_alias)
-			break;
 		if (!handle_alias(argcp, argv))
 			break;
-		done_alias = 1;
+		done_alias++;
 	}
 
 	return done_alias;
-- 
2.19.0.rc1.2.g7460ee143