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From: Tim Schumacher <timschumi@gmx.de>
To: Junio C Hamano <gitster@pobox.com>, Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, pclouds@gmail.com
Subject: Re: [PATCH v3] Allow aliases that include other aliases
Date: Thu, 6 Sep 2018 21:31:10 +0200	[thread overview]
Message-ID: <4f814d67-c384-6d1e-a988-97cc25e32475@gmx.de> (raw)
In-Reply-To: <xmqqy3cezcz5.fsf@gitster-ct.c.googlers.com>

On 06.09.18 20:40, Junio C Hamano wrote:
> Jeff King <peff@peff.net> writes:
> 
>> On Thu, Sep 06, 2018 at 12:16:58PM +0200, Tim Schumacher wrote:
>>
>>> @@ -691,17 +692,23 @@ static int run_argv(int *argcp, const char ***argv)
>>>   		/* .. then try the external ones */
>>>   		execv_dashed_external(*argv);
>>>   
>>> -		/* It could be an alias -- this works around the insanity
>>> +		if (string_list_has_string(&cmd_list, *argv[0]))
>>> +			die(_("loop alias: %s is called twice"), *argv[0]);
>>
>> I pointed this out in my response to Ævar, but I want to make sure it
>> gets seen. This call assumes the list is sorted, but...
>>
>>> +		string_list_append(&cmd_list, *argv[0]);
>>
>> This will create an unsorted list. You'd have to use
>> string_list_insert() here for a sorted list, or
>> unsorted_string_list_has_string() in the earlier call.
> 
> Correct.
> 
> Also, normal users who have never seen this loop that implements
> alias expansion would not have a clue when they see "called twice".
> 
> I actually think the caller should also pass cmd to run_argv() and
> then we should use it (and not argv[]) in this die() message.

Could we just save the first element of the original argv for that
purpose? Or alternatively, use the first stored element in the
command list?

> When
> the original command was foo that is aliased to bar, which in turn
> is aliased to baz, which in turn is aliased to bar, especially that
> "git foo" invocation was in a random script written six weeks ago by
> the user, it would be a lot more helpful to see
> 
>      "alias loop detected: expansion of 'git foo' does not terminate"
> 
> than
> 
>      "loop alias: bar is called twice".
> 
> given that 'bar' is not something the user called, or written in the
> script she wrote six weeks ago.

Indeed, printing the command that the user called is a better message
than the command that is the entry-point of the loop. I'll change it
in v4.

> 
>> It's unfortunate that string_list makes this so easy to get wrong.
>>
>>> +
>>> +		/*
>>> +		 * It could be an alias -- this works around the insanity
>>>   		 * 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++;
>>
>> I don't think anybody cares about done_alias being an accurate count.
>> Should we just leave this as-is?
> 
> Good point.  The only caller treats it as a bool (i.e. "should the
> failure be reported as failure to expand an alias cmd which resulted
> in (updated) argv[0] that is not a git command?").
> 

As the string-list has its own counter, I guess the done_alias variable
can be reverted to a simple 0/1 value.

  parent reply	other threads:[~2018-09-06 19:31 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-05  8:54 [RFC PATCH v2] Allow aliases that include other aliases Tim Schumacher
2018-09-05 15:48 ` Duy Nguyen
2018-09-05 19:02   ` Tim Schumacher
2018-09-05 17:12 ` Junio C Hamano
2018-09-05 19:12   ` Tim Schumacher
2018-09-05 17:34 ` Jeff King
2018-09-05 20:02   ` Tim Schumacher
2018-09-06 13:38     ` Ævar Arnfjörð Bjarmason
2018-09-06 14:17     ` Ævar Arnfjörð Bjarmason
2018-10-18 22:57       ` [PATCH] alias: detect loops in mixed execution mode Ævar Arnfjörð Bjarmason
2018-10-19  8:28         ` Ævar Arnfjörð Bjarmason
2018-10-19 22:09           ` Jeff King
2018-10-20 10:52             ` Ævar Arnfjörð Bjarmason
2018-10-19 22:07         ` Jeff King
2018-10-20 11:14           ` Ævar Arnfjörð Bjarmason
2018-10-20 18:58             ` Jeff King
2018-10-20 19:18               ` Ævar Arnfjörð Bjarmason
2018-10-22 21:15                 ` Jeff King
2018-10-22 21:28                   ` Ævar Arnfjörð Bjarmason
2018-10-22  1:23               ` Junio C Hamano
2018-10-26  8:39               ` Jeff King
2018-10-26 12:44                 ` Ævar Arnfjörð Bjarmason
2018-10-29  3:44                 ` Junio C Hamano
2018-10-29 14:17                   ` Jeff King
2018-09-05 21:51   ` [RFC PATCH v2] Allow aliases that include other aliases Junio C Hamano
2018-09-06 10:16 ` [PATCH v3] " Tim Schumacher
2018-09-06 14:01   ` Ævar Arnfjörð Bjarmason
2018-09-06 14:57     ` Jeff King
2018-09-06 15:10       ` Ævar Arnfjörð Bjarmason
2018-09-06 16:18         ` Jeff King
2018-09-06 19:05       ` Tim Schumacher
2018-09-06 19:17         ` Jeff King
2018-09-06 14:59   ` Jeff King
2018-09-06 18:40     ` Junio C Hamano
2018-09-06 19:05       ` Jeff King
2018-09-06 19:31       ` Tim Schumacher [this message]
2018-09-07 22:44 ` [RFC PATCH v4 1/3] Add support for nested aliases Tim Schumacher
2018-09-07 22:44   ` [RFC PATCH v4 2/3] Show the call history when an alias is looping Tim Schumacher
2018-09-08 13:34     ` Duy Nguyen
2018-09-08 16:29       ` Jeff King
2018-09-07 22:44   ` [RFC PATCH v4 3/3] t0014: Introduce alias testing suite Tim Schumacher
2018-09-07 23:38     ` Eric Sunshine
2018-09-14 23:12       ` Tim Schumacher
2018-09-16  7:21         ` Eric Sunshine
2018-09-08 13:28   ` [RFC PATCH v4 1/3] Add support for nested aliases Duy Nguyen
2018-09-16  7:46     ` Tim Schumacher
2018-09-17 15:37       ` Junio C Hamano
2018-09-21 12:45         ` Tim Schumacher
2018-09-21 15:59           ` Junio C Hamano
2018-09-16  7:50   ` [PATCH v5 " Tim Schumacher
2018-09-16  7:50     ` [PATCH v5 2/3] Show the call history when an alias is looping Tim Schumacher
2018-09-16  7:50     ` [PATCH v5 3/3] t0014: Introduce an alias testing suite Tim Schumacher

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