Re: [PATCH v5 1/1] diff.c: When appropriate, use utf8_strwidth()

From: Junio C Hamano <gitster@pobox.com>
Date: Oct 10, 2022, 21:58 UTC
Message-ID: <xmqq35bv1gu5.fsf@gitster.g>
In-Reply-To: <20220926184308.5oaaoopod36igq6i@tb-raspi4>

Torsten Bögershausen <tboegi@web.de> writes:

Show 9 quoted lines

> On Wed, Sep 14, 2022 at 09:40:04AM -0700, Junio C Hamano wrote:
>
> []
>
>> I think I spotted two remaining "bugs" that are left unfixed with
>> this patch..
>> ...
> How should we proceed here ?
> This patch fixes one, and only one, reported bug,

But then two more were reported in the message you are responding to, and they stem from the same underlying logic bug where byte count and display columns are mixed interchangeably.

> "git log --graph" was mentioned.
> Do we have test cases, that test this ?
> How easy are they converted into unicode instead of ASCII ?

The graph stuff pushes your "start of line" to the right, making the available screen real estate narrower. I do not think in the current code we need to worry about unicode vs ascii (IIRC, we stick to ASCII graphics while drawing lines), but we do need to take into account the fact that ANSI COLOR escape sequences have non-zero byte count while occupying zero display columns.

The other bug about the code that finds which / to use to abbreviate a long pathname on diffstat lines does involve byte vs column that comes from unicode. From the bug description in the message you are responding to, if we have a directory name whose display columns and byte count are significantly different, the end result by chopping with the current code would end up wider than it should be, which sounds like a recipe to cook up a test case to me.