Re: [PATCH] convert: fail gracefully upon missing clean cmd on required filter

From: Junio C Hamano <gitster@pobox.com>
To: Matheus Tavares <matheus.bernardino@usp.br>
Cc: git@vger.kernel.org, Steffen Prohaska <prohaska@zib.de>
Subject: Re: [PATCH] convert: fail gracefully upon missing clean cmd on required filter
Date: Thu, 25 Feb 2021 15:05:50 -0800	[thread overview]
Message-ID: <xmqqsg5jsq7l.fsf@gitster.g> (raw)
In-Reply-To: <b33d0dc82f5ff1fac6772e533bbf21eecfae44ed.1614277014.git.matheus.bernardino@usp.br> (Matheus Tavares's message of "Thu, 25 Feb 2021 15:16:56 -0300")

Matheus Tavares <matheus.bernardino@usp.br> writes:

> The gitattributes documentation mentions that either the clean cmd or
> the smudge cmd can be left unspecified in a filter definition. However,
> when the filter is marked as 'required', the absence of any one of these
> two should be treated as an error. Git already fails under these
> circumstances, but not always in a pleasant way: omitting a clean cmd in
> a required filter triggers an assertion error which leaves the user with
> a quite verbose message:
>
> git: convert.c:1462: convert_to_git_filter_fd: Assertion "ca.drv->clean || ca.drv->process" failed.
>
> This assertion and the one above it are not really necessary, as the
> apply_filter() call bellow them already performs the same checks. And
> when these conditions are not met, the function returns 0, making the
> caller die() with a much nicer message. (Also note that die()-ing here
> is the right behavior as `would_convert_to_git_filter_fd() == true` is a
> precondition to use convert_to_git_filter_fd(), and the former is only
> true when the filter is required.) So remove both assertions and add two
> regression tests to make sure that git fails nicely when either the
> smudge or clean command is missing on a required filter.

Makes sense.

Will queue, thanks.