Subject: Re: Incorrect behavior from git checkout --patch

From: Phillip Wood <[email-masked]>
Date: Sun, 11 Aug 2019 10:54:31 +0100

Hi Dave

Thanks for the bug report. I've tried to reproduce it on the latest 
master, version 2.22.0 and 2.20.1 and am unable to do so. I thought it 
might be related to a bug I recently fixed[1] but it does not appear to 
be. I've appended the files I used below just in case I made a mistake 
translating your patches to files that can be used with git checkout.

Best Wishes

Phillip

[1] 
https://github.com/git/git/commit/1b074e15d0f976be2bc14f9528874a841c055213#diff-588be9a03d1f7e33db12f186aad5fde9

pre-image

block_one {
line 1
line 2
line 3
2 4 6 8
line 4
line 5
line 6
2 4 6 8
line 7
line 8
line 9
2 4 6 8
line 10
line 11
line 12
}

block_two {
line 1
line 2
line 3
2 5 6 9
line 4
line 5
line 6
2 5 6 9
line 7
line 8
line 9
2 5 6 9
line 10
line 11
line 12
}

post-image

block_one {
line 1
line 1.5
line 2
line 2.5
line 3
2 4 6 8
line 4
line 4.5
line 5
line 5.5
line 6
2 4 6 8
line 7
line 7.5
line 8
line 8.5
line 9
2 4 6 8
line 10
line 10.5
line 11
line 11.5
line 12
}

block_two {
line 1
line 1.5
line 2
line 2.5
line 3
2 5 6 9
line 4
line 4.5
line 5
line 5.5
line 6
2 5 6 9
line 7
line 7.5
line 8
line 8.5
line 9
2 5 6 9
line 10
line 10.5
line 11
line 11.5
line 12
}

On 10/08/2019 21:12, Dave Kaminski wrote:
> I am observing git checkout --patch making changes to the wrong lines of a file.
> 
> This is with a clean install of git version 2.20.1 on a debian docker
> container (image tag 10.0 which is also "latest" as of this writing).
> 
> With a diff that looks like the following:
> 
> diff --git a/file.txt b/file.txt
> index 868aa22..ea4d786 100644
> --- a/file.txt
> +++ b/file.txt
> @@ -1,35 +1,51 @@
>   block_one {
>   line 1
> +line 1.5
>   line 2
> +line 2.5
>   line 3
>   2 4 6 8
>   line 4
> +line 4.5
>   line 5
> +line 5.5
>   line 6
>   2 4 6 8
>   line 7
> +line 7.5
>   line 8
> +line 8.5
>   line 9
>   2 4 6 8
>   line 10
> +line 10.5
>   line 11
> +line 11.5
>   line 12
>   }
> 
>   block_two {
>   line 1
> +line 1.5
>   line 2
> +line 2.5
>   line 3
> -2 5 6 9
> +2 4 6 8
>   line 4
> +line 4.5
>   line 5
> +line 5.5
>   line 6
> -2 5 6 9
> +2 4 6 8
>   line 7
> +line 7.5
>   line 8
> +line 8.5
>   line 9
> -2 5 6 9
> +2 4 6 8
>   line 10
> +line 10.5
>   line 11
> +line 11.5
>   line 12
>   }
> 
> doing a `git checkout --patch -- ./file.txt`, splitting the diff into
> hunks, and discarding all of the hunks that begin with numbers, e.g.
> 
> @@ -22,3 +32,3 @@
>   line 3
> -2 5 6 9
> +2 4 6 8
>   line 4
> 
> the expected state of the file in the working directory is this:
> 
> diff --git a/file.txt b/file.txt
> index 868aa22..9ab67a1 100644
> --- a/file.txt
> +++ b/file.txt
> @@ -1,35 +1,51 @@
>   block_one {
>   line 1
> +line 1.5
>   line 2
> +line 2.5
>   line 3
>   2 4 6 8
>   line 4
> +line 4.5
>   line 5
> +line 5.5
>   line 6
>   2 4 6 8
>   line 7
> +line 7.5
>   line 8
> +line 8.5
>   line 9
>   2 4 6 8
>   line 10
> +line 10.5
>   line 11
> +line 11.5
>   line 12
>   }
> 
>   block_two {
>   line 1
> +line 1.5
>   line 2
> +line 2.5
>   line 3
>   2 5 6 9
>   line 4
> +line 4.5
>   line 5
> +line 5.5
>   line 6
>   2 5 6 9
>   line 7
> +line 7.5
>   line 8
> +line 8.5
>   line 9
>   2 5 6 9
>   line 10
> +line 10.5
>   line 11
> +line 11.5
>   line 12
>   }
> 
> but instead the actual state of the file is this:
> 
> diff --git a/file.txt b/file.txt
> index 868aa22..76fe65d 100644
> --- a/file.txt
> +++ b/file.txt
> @@ -1,35 +1,51 @@
>   block_one {
>   line 1
> +line 1.5
>   line 2
> +line 2.5
>   line 3
>   2 4 6 8
>   line 4
> +line 4.5
>   line 5
> +line 5.5
>   line 6
>   2 4 6 8
>   line 7
> +line 7.5
>   line 8
> +line 8.5
>   line 9
> -2 4 6 8
> +2 5 6 9
>   line 10
> +line 10.5
>   line 11
> +line 11.5
>   line 12
>   }
> 
>   block_two {
>   line 1
> +line 1.5
>   line 2
> +line 2.5
>   line 3
>   2 5 6 9
>   line 4
> +line 4.5
>   line 5
> +line 5.5
>   line 6
>   2 5 6 9
>   line 7
> +line 7.5
>   line 8
> +line 8.5
>   line 9
> -2 5 6 9
> +2 4 6 8
>   line 10
> +line 10.5
>   line 11
> +line 11.5
>   line 12
>   }
> 
> See the changes between "line 9" and "line 10" in both blocks that are
> not correct.
>