Re: Unexpected git diff output during merge conflict

From: Jeff King <peff@peff.net>
Date: Feb 8, 2018, 11:25 UTC
Message-ID: <20180208112508.GA3506@sigill.intra.peff.net>
In-Reply-To: <CAF=vhqdJ2fByjSVt37b34wQUFo5_tb7rHbCddsaCzdvKywSBdg@mail.gmail.com>

On Thu, Feb 08, 2018 at 10:51:57AM +0000, Nick O'Leary wrote:

Show 26 quoted lines

> $ git diff README.md
> diff --cc README.md
> index 61d78b2,620d806..0000000
> --- a/README.md
> +++ b/README.md
> @@@ -1,7 -1,1 +1,11 @@@
>  -This is my default readme
> ++<<<<<<< HEAD
>  +merged-history-test
>  +===================
>  +
>  +### About
>  +
>  +This is your project's README.md file. It helps users understand what your
> - project does, how to use it and anything else they may need to know.
> ++project does, how to use it and anything else they may need to know.
> ++=======
> ++This is my default readme
> ++>>>>>>> dev
> 
> This does not look right to me. The 'This is my default readme' line
> has ++ at the start - suggesting its new to both parent copies of the
> file, which isn't the case - it came from the dev branch so should be
> prefixed with '+ '.
> I'm also not clear why the line beginning 'project does' has both a -
> and ++ prefix.

Are you sure there aren't whitespace differences in those two lines?

For instance, if I do:

  # base commit
  git init
  git commit --allow-empty -m base

  # one side; note missing newline!
  printf 'this is my default readme' >file
  git add file
  git commit -m default

  # other side
  git checkout -b other HEAD^
  {
	echo this is a longer
	echo and more involved
	echo README
  } >file
  git add file
  git commit -m longer

  # and now merge and get a conflict
  git merge master

Then I get similar output to you. The content with merge-conflicts can't represent the original lack-of-newline for that file, because of course there's another ">>>" line after it.

If I swap out the printf for echo, adding the newline, then it produces the output you'd expect.

-Peff