Re: git 2.34.0: Behavior of `**` in gitignore is different from previous versions.

From: Derrick Stolee <stolee@gmail.com>
Date: Nov 18, 2021, 22:09 UTC
Message-ID: <2bd2269f-c7f1-7afb-7052-48fac148dffd@gmail.com>
In-Reply-To: <YZaHpJKeyDEY8qKW@coredump.intra.peff.net>

On 11/18/2021 12:04 PM, Jeff King wrote:

Show 35 quoted lines

> On Thu, Nov 18, 2021 at 08:11:04PM +0330, Danial Alihosseini wrote:
> 
>> What did you do before the bug happened? (Steps to reproduce your issue)
>> Consider the following project structure
>> - data
>>   - data1
>>     - file1
>>     - file1.txt
>>   - data2
>>     - file2
>>     - file2.txt
>> - .gitignore
>>
>>
>> `.gitignore` is as follows:
>> ```
>> data/**
>> !data/**/
>> !data/**/*.txt
>> ```
>> What did you expect to happen? (Expected behavior)
>>
>> I expect all files in `data` folder to be ignored except `.txt` files.
>>
>> What happened instead? (Actual behavior)
>>
>> `file1` and `file2` are not ignored.
>> Here is the `check-ignore` output:
>> ```
>> $ git check-ignore -v data/data1/file1
>> .gitignore:2:!/data/**/ data/data1/file1
>> ```
> 
> Thanks for an easy reproduction. It looks like this changed in
> f6526728f9 (dir: select directories correctly, 2021-09-24). Author cc'd.

Thanks for the bisect and CC.

> The key thing seems to be that the second line of your .gitignore should
> match only directories (because of the trailing slash), but no longer
> does.

Doesn't "matching only directories" mean it would match everything within that directory? (It also means that "data/file" is not matched, which is still correct.)

My interpretation of these patterns is that everything in data/data1/ and data/data2/ should not be ignored, making it seem like the change fixed a bug (it definitely changed behavior).

Just for extra clarity, this test currently passes:

test_expect_success 'directories and ** matches' '
	cat >.gitignore <<-\EOF &&
	data/**
	!data/**/
	!data/**/*.txt
	EOF
	git check-ignore file \
		data/file data/data1/file1 data/data1/file1.txt \
		data/data2/file2 data/data2/file2.txt >actual &&
	cat >expect <<-\EOF &&
	data/file
	EOF
	test_cmp expect actual
'

but the previous behavior would have passed this test:

test_expect_success 'directories and ** matches' '
	cat >.gitignore <<-\EOF &&
	data/**
	!data/**/
	!data/**/*.txt
	EOF
	git check-ignore file \
		data/file data/data1/file1.txt \
		data/data2/file2.txt >actual &&
	cat >expect <<-\EOF &&
	data/file
	EOF
	test_cmp expect actual
'

I seek more clarity on this. Specifically: if we match a directory then should we not also match the contents within?

Thanks, -Stolee