From: Jeff King <peff@peff•net>
To: Kristoffer Haugsbakk <kristofferhaugsbakk@fastmail•com>
Cc: Kristoffer Haugsbakk <code@khaugsbakk•name>,
git@vger•kernel.org, Eric Sunshine <sunshine@sunshineco•com>,
Patrick Steinhardt <ps@pks•im>
Subject: Re: [PATCH v4 2/7] git: allow alias-shadowing deprecated builtins
Date: Sat, 13 Sep 2025 18:06:09 -0400 [thread overview]
Message-ID: <20250913220609.GA435444@coredump.intra.peff.net> (raw)
In-Reply-To: <98d206ca-3dc1-42cc-9f01-e3241d5a24af@app.fastmail.com>
On Sat, Sep 13, 2025 at 04:10:57PM +0200, Kristoffer Haugsbakk wrote:
> The code in the `while(1)` speculatively adds commands to the list
> before finding out if it’s an alias. Let’s instead move it inside
> `handle_alias(...)` and in turn only run this logic when we have found
> an alias.
>
> This is not a refactor since the error output is changed; we will
> now print
>
> '<cmd1>' is aliased to '<cmd2>'
>
> while iterating in addition to the final `fatal` message.
If you want to get rid of that last paragraph, I think it really is as
simple as checking the expanded alias new_argv[0] as soon as we see it,
like:
diff --git a/git.c b/git.c
index 06de0bacf3..f11ce416a3 100644
--- a/git.c
+++ b/git.c
@@ -425,7 +425,9 @@ static int handle_alias(struct strvec *args, struct string_list *cmd_list)
if (!strcmp(alias_command, new_argv[0]))
die(_("recursive alias: %s"), alias_command);
- seen = unsorted_string_list_lookup(cmd_list, args->v[0]);
+ string_list_append(cmd_list, args->v[0]);
+
+ seen = unsorted_string_list_lookup(cmd_list, new_argv[0]);
if (seen) {
struct strbuf sb = STRBUF_INIT;
for (size_t i = 0; i < cmd_list->nr; i++) {
@@ -441,8 +443,6 @@ static int handle_alias(struct strvec *args, struct string_list *cmd_list)
" not terminate:%s"), cmd_list->items[0].string, sb.buf);
}
- string_list_append(cmd_list, args->v[0]);
-
trace_argv_printf(new_argv,
"trace: alias expansion: %s =>",
alias_command);
It is important to move the append of args->v[0] up (though arguably it
should be alias_command here, which is a local-variable alias that the
rest of the function uses). Adding it up-front is not needed for loop
detection, but it is shown as part of the output when we do find a loop.
You could _also_ ditch the "recursive alias" check above at that point,
though I think it produces a slightly nicer message:
$ ./git -c alias.foo=foo foo
fatal: recursive alias: foo
vs:
$ ./git -c alias.foo=foo foo
fatal: alias loop detected: expansion of 'foo' does not terminate:
foo <==
Though perhaps if the output code marked it as both the start and end of
the loop it would be more sensible. Maybe like:
diff --git a/git.c b/git.c
index f11ce416a3..f1a83f2e6a 100644
--- a/git.c
+++ b/git.c
@@ -422,9 +422,6 @@ static int handle_alias(struct strvec *args, struct string_list *cmd_list)
if (count < 1)
die(_("empty alias for %s"), alias_command);
- if (!strcmp(alias_command, new_argv[0]))
- die(_("recursive alias: %s"), alias_command);
-
string_list_append(cmd_list, args->v[0]);
seen = unsorted_string_list_lookup(cmd_list, new_argv[0]);
@@ -436,8 +433,8 @@ static int handle_alias(struct strvec *args, struct string_list *cmd_list)
strbuf_addf(&sb, "\n %s", item->string);
if (item == seen)
strbuf_addstr(&sb, " <==");
- else if (i == cmd_list->nr - 1)
- strbuf_addstr(&sb, " ==>");
+ if (i == cmd_list->nr - 1)
+ strbuf_addstr(&sb, item == seen ? ">" : " ==>");
}
die(_("alias loop detected: expansion of '%s' does"
" not terminate:%s"), cmd_list->items[0].string, sb.buf);
I dunno. Maybe it is not worth tinkering with too much. But the "this
changes the output" justification from your proposed message seems to me
an indication that the refactor is a little iffy.
-Peff
next prev parent reply other threads:[~2025-09-13 22:06 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-27 16:29 [PATCH 0/4] you-still-use-that??: improve breaking changes troubleshooting kristofferhaugsbakk
2025-08-27 16:29 ` [PATCH 1/4] usage: help the user help themselves kristofferhaugsbakk
2025-08-27 20:36 ` Kristoffer Haugsbakk
2025-08-27 21:02 ` Eric Sunshine
2025-08-27 21:20 ` Junio C Hamano
2025-08-27 21:27 ` Eric Sunshine
2025-08-27 22:26 ` Junio C Hamano
2025-08-28 6:39 ` Kristoffer Haugsbakk
2025-08-28 15:09 ` Junio C Hamano
2025-09-03 16:50 ` Eric Sunshine
2025-09-03 17:53 ` Kristoffer Haugsbakk
2025-09-03 21:21 ` Eric Sunshine
2025-09-03 21:41 ` Kristoffer Haugsbakk
2025-09-03 21:44 ` Jeff King
2025-09-03 22:11 ` Eric Sunshine
2025-09-04 6:57 ` Kristoffer Haugsbakk
2025-09-05 13:11 ` Jeff King
2025-09-09 20:01 ` Kristoffer Haugsbakk
2025-08-27 21:14 ` Junio C Hamano
2025-08-27 16:29 ` [PATCH 2/4] whatchanged: tell users the git-log(1) equivalent kristofferhaugsbakk
2025-08-27 16:45 ` Junio C Hamano
2025-08-27 16:48 ` Junio C Hamano
2025-08-27 17:08 ` Kristoffer Haugsbakk
2025-08-28 12:07 ` Kristoffer Haugsbakk
2025-08-27 16:29 ` [PATCH 3/4] whatchanged: remove not-even-shorter clause kristofferhaugsbakk
2025-08-27 16:29 ` [PATCH 4/4] BreakingChanges: remove claim about whatchanged reports kristofferhaugsbakk
2025-08-27 16:43 ` [PATCH 0/4] you-still-use-that??: improve breaking changes troubleshooting Junio C Hamano
2025-08-29 15:21 ` [PATCH v2 " kristofferhaugsbakk
2025-08-29 15:21 ` [PATCH v2 1/4] you-still-use-that??: help the user help themselves kristofferhaugsbakk
2025-08-29 15:21 ` [PATCH v2 2/4] whatchanged: tell users the git-log(1) equivalent kristofferhaugsbakk
2025-08-29 15:21 ` [PATCH v2 3/4] whatchanged: remove not-even-shorter clause kristofferhaugsbakk
2025-08-29 15:21 ` [PATCH v2 4/4] BreakingChanges: remove claim about whatchanged reports kristofferhaugsbakk
2025-09-08 15:36 ` [PATCH v3 0/8] you-still-use-that??: improve breaking changes troubleshooting kristofferhaugsbakk
2025-09-08 15:36 ` [PATCH v3 1/8] git: add `deprecated` category to --list-cmds kristofferhaugsbakk
2025-09-09 6:43 ` Patrick Steinhardt
2025-09-09 8:02 ` Kristoffer Haugsbakk
2025-09-08 15:36 ` [PATCH v3 2/8] git: make the two loops look more symmetric kristofferhaugsbakk
2025-09-08 15:36 ` [PATCH v3 3/8] git: allow alias-shadowing deprecated builtins kristofferhaugsbakk
2025-09-08 20:47 ` Junio C Hamano
2025-09-08 21:11 ` Jeff King
2025-09-08 21:55 ` Junio C Hamano
2025-09-09 6:25 ` Kristoffer Haugsbakk
2025-09-08 15:36 ` [PATCH v3 4/8] t0014: test shadowing of aliases for a sample of builtins kristofferhaugsbakk
2025-09-08 15:36 ` [PATCH v3 5/8] you-still-use-that??: help the user help themselves kristofferhaugsbakk
2025-09-08 15:36 ` [PATCH v3 6/8] whatchanged: tell users the git-log(1) equivalent kristofferhaugsbakk
2025-09-08 15:36 ` [PATCH v3 7/8] whatchanged: remove not-even-shorter clause kristofferhaugsbakk
2025-09-08 15:36 ` [PATCH v3 8/8] BreakingChanges: remove claim about whatchanged reports kristofferhaugsbakk
2025-09-09 19:45 ` [PATCH v4 0/7] you-still-use-that??: improve breaking changes troubleshooting kristofferhaugsbakk
2025-09-09 19:45 ` [PATCH v4 1/7] git: add `deprecated` category to --list-cmds kristofferhaugsbakk
2025-09-09 21:44 ` Junio C Hamano
2025-09-10 11:41 ` Patrick Steinhardt
2025-09-10 15:50 ` Jeff King
2025-09-10 21:40 ` Junio C Hamano
2025-09-10 20:23 ` Kristoffer Haugsbakk
2025-09-09 19:45 ` [PATCH v4 2/7] git: allow alias-shadowing deprecated builtins kristofferhaugsbakk
2025-09-10 5:13 ` Jeff King
2025-09-10 15:48 ` Jeff King
2025-09-10 17:58 ` Kristoffer Haugsbakk
2025-09-10 18:34 ` Jeff King
2025-09-11 17:31 ` Kristoffer Haugsbakk
2025-09-11 20:32 ` Jeff King
2025-09-11 20:43 ` Jeff King
2025-09-13 14:10 ` Kristoffer Haugsbakk
2025-09-13 22:06 ` Jeff King [this message]
2025-09-14 17:24 ` Kristoffer Haugsbakk
2025-09-15 1:44 ` Jeff King
2025-09-15 6:27 ` Kristoffer Haugsbakk
2025-09-11 20:44 ` Jeff King
2025-09-11 21:19 ` Junio C Hamano
2025-09-13 21:50 ` Kristoffer Haugsbakk
2025-09-09 19:45 ` [PATCH v4 3/7] t0014: test shadowing of aliases for a sample of builtins kristofferhaugsbakk
2025-09-09 19:45 ` [PATCH v4 4/7] you-still-use-that??: help the user help themselves kristofferhaugsbakk
2025-09-09 19:45 ` [PATCH v4 5/7] whatchanged: tell users the git-log(1) equivalent kristofferhaugsbakk
2025-09-09 19:45 ` [PATCH v4 6/7] whatchanged: remove not-even-shorter clause kristofferhaugsbakk
2025-09-09 19:45 ` [PATCH v4 7/7] BreakingChanges: remove claim about whatchanged reports kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 0/8] you-still-use-that??: improve breaking changes troubleshooting kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 1/8] git: add `deprecated` category to --list-cmds kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 2/8] git: move seen-alias bookkeeping into handle_alias(...) kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 3/8] git: allow alias-shadowing deprecated builtins kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 4/8] t0014: test shadowing of aliases for a sample of builtins kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 5/8] you-still-use-that??: help the user help themselves kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 6/8] whatchanged: hint about git-log(1) and aliasing kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 7/8] whatchanged: remove not-even-shorter clause kristofferhaugsbakk
2025-09-14 19:49 ` [PATCH v5 8/8] BreakingChanges: remove claim about whatchanged reports kristofferhaugsbakk
2025-09-15 19:19 ` [PATCH v5 0/8] you-still-use-that??: improve breaking changes troubleshooting Junio C Hamano
2025-09-16 20:47 ` Kristoffer Haugsbakk
2025-09-16 23:24 ` Jeff King
2025-09-17 15:41 ` Kristoffer Haugsbakk
2025-09-17 16:25 ` Junio C Hamano
2025-09-17 20:24 ` [PATCH v6 0/9] " kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 1/9] Makefile: don’t add whatchanged after it has been removed kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 2/9] git: add `deprecated` category to --list-cmds kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 3/9] git: move seen-alias bookkeeping into handle_alias(...) kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 4/9] git: allow alias-shadowing deprecated builtins kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 5/9] t0014: test shadowing of aliases for a sample of builtins kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 6/9] you-still-use-that??: help the user help themselves kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 7/9] whatchanged: hint about git-log(1) and aliasing kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 8/9] whatchanged: remove not-even-shorter clause kristofferhaugsbakk
2025-09-17 20:24 ` [PATCH v6 9/9] BreakingChanges: remove claim about whatchanged reports kristofferhaugsbakk
2025-09-18 18:31 ` [PATCH v6 0/9] you-still-use-that??: improve breaking changes troubleshooting Jeff King
2025-09-18 20:21 ` Junio C Hamano
2025-09-18 20:28 ` Kristoffer Haugsbakk
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