Re: [PATCH] difftool: support repositories with .git-files

> Modern versions of "git submodule" use .git-files to setup the
> submodule directory.  When run in a "git submodule"-created
> repository "git difftool --dir-diff" dies with the following
> error:
>
> 	$ git difftool -d HEAD~
> 	fatal: This operation must be run in a work tree
> 	diff --raw --no-abbrev -z HEAD~: command returned error: 128
>
> core.worktree is relative to the .git directory but the logic
> in find_worktree() does not account for it.
>
> Use `git rev-parse --show-toplevel` to find the worktree so that
> the dir-diff feature works inside a submodule.
>
> Reported-by: Gábor Lipták <gabor.liptak@gmail.com>
> Helped-by: Jens Lehmann <jens.lehmann@web.de>
> Helped-by: John Keeping <john@keeping.me.uk>
> Signed-off-by: David Aguilar <davvid@gmail.com>
> ---

>  git-difftool.perl | 18 ++----------------
>  1 file changed, 2 insertions(+), 16 deletions(-)
>
> diff --git a/git-difftool.perl b/git-difftool.perl
> index e57d3d1..18ca61e 100755
> --- a/git-difftool.perl
> +++ b/git-difftool.perl
> @@ -39,24 +39,10 @@ USAGE
>  
>  sub find_worktree
>  {
> -	my ($repo) = @_;
> -
>  	# Git->repository->wc_path() does not honor changes to the working
>  	# tree location made by $ENV{GIT_WORK_TREE} or the 'core.worktree'
>  	# config variable.
> -	my $worktree;
> -	my $env_worktree = $ENV{GIT_WORK_TREE};
> -	my $core_worktree = Git::config('core.worktree');
> -
> -	if (defined($env_worktree) and (length($env_worktree) > 0)) {
> -		$worktree = $env_worktree;
> -	} elsif (defined($core_worktree) and (length($core_worktree) > 0)) {
> -		$worktree = $core_worktree;
> -	} else {
> -		$worktree = $repo->wc_path();
> -	}
> -
> -	return $worktree;
> +	return Git::command_oneline('rev-parse', '--show-toplevel');
>  }
>  
>  sub print_tool_help
> @@ -418,7 +404,7 @@ sub dir_diff
>  	my $rc;
>  	my $error = 0;
>  	my $repo = Git->repository();
> -	my $workdir = find_worktree($repo);
> +	my $workdir = find_worktree();
>  	my ($a, $b, $tmpdir, @worktree) =
>  		setup_dir_diff($repo, $workdir, $symlinks);