Re: Git 2.7.0 gitignore behaviour regression

From: Duy Nguyen <pclouds@gmail.com>
Date: Jan 6, 2016, 09:42 UTC
Message-ID: <CACsJy8AQ9s4VkFn+TNJLD55xJc40+-54BTYbC4Os71uSkL1QSA@mail.gmail.com>
In-Reply-To: <20160105150602.GA4130@sigill.intra.peff.net>

On Tue, Jan 5, 2016 at 10:06 PM, Jeff King <peff@peff.net> wrote:

Show 36 quoted lines

> On Tue, Jan 05, 2016 at 02:40:16PM +0000, Mike McQuaid wrote:
>
>> Homebrew has a series of convoluted .gitignore rules due to our
>> special/weird use-case of wanting to ignore everything in a working
>> directory except a select few files/directories. We experienced a bug
>> with our .gitignore file for users using Git 2.7.0. This may well be a
>> valid WONTFIX or intentional behaviour change but I wanted to flag it
>> in case it wasn’t.
>>
>> Here’s a minimal test case:
>>
>> - Create an empty git repository in a directory with `git init`
>> - Create a directory named ‘a' containing a file named ‘b' with `mkdir a && touch a/b`
>> - Create a ‘gitignore’ file with the following contents:
>> ```
>> */
>> /a
>> !/a/*
>> ```
>> - Run `git status --short`.
>>
>> The output with Git 2.6.4 is:
>> ```
>> ?? .gitignore
>> ```
>>
>> The output with Git 2.7.0 is:
>> ```
>> ?? .gitignore
>> ?? a/
>> ```
>
> Thanks for giving a clear example. This bisects to Duy's 57534ee (dir.c:
> don't exclude whole dir prematurely if neg pattern may match,
> 2015-09-21). AFAICT (and I don't recall looking over this patch
> previously), what you are seeing is the intended effect of the patch.

Yeah.. I think it's the only relevant commit in 2.7.0 cycle anyway. These patterns "/a" followed by "!/a/*" were wrecking my head. But I finally decided 2.7 output makes more sense. You asked to un-ignore everything inside 'a' so we can't treat 'a' as (entirely) ignored and hide it away.

> I'm sympathetic that in making that use-case work, we might have
> regressed another one, but it's hard to tell from the small example. Can
> you elaborate on your use case? Why are you both ignoring and unignoring
> everything in the directory?

Also how bad this affects you (widely-used 'wrong' behavior can become 'right', and my change a regression as a result)

-- 
Duy