Re: [PATCH 1/2] git-jump: always specify column 1 for diff entries

["Martin Ågren" <martin.agren@gmail.com>]

On Sun, 15 Sept 2024 at 13:18, Jeff King <peff@peff.net> wrote:
>
> When we generate a quickfix entry for a diff hunk, we provide just the
> filename and line number along with the content, like:
>
>   file:1: contents of the line
>
> This can be a problem if the line itself looks like a quickfix header.
> For example (and this is adapted from a real-world case that bit me):
>
>   echo 'static_lease 10:11:12:13:14:15:16 10.0.0.1' >file
>   git add file
>   echo change >file
>
> produces:
>
>   file:1: static_lease 10:11:12:13:14:15:16 10.0.0.1
>
> which is ambiguous. It could be line 1 of "file", or line 11 of the file
> "file:1: static_lease 10", and so on. In the case of vim's default
> config, it seems to prefer the latter (you can configure "errorformat"
> with a variety of patterns, but out of the box it matches some common
> ones).

I've never hit this, but it doesn't look too crazy. A couple of digits
and a colon and things begin to match. Ok.

> One easy way to fix this is to provide a column number, like:
>
>   file:1:1: static_lease 10:11:12:13:14:15:16 10.0.0.1
>
> which causes vim to prefer line 1 of "file" again (due to the preference
> order of the various patterns in the default errorformat).

Makes sense.

> There are other options. For example, at least in my version of vim,
> wrapping the file in quotation marks like:
>
>   "file":1: static_lease 10:11:12:13:14:15:16 10.0.0.1
>
> also works. That perhaps would the right thing even if you had the silly
> file name "file:1:1: foo 10". But it's not clear what would happen if
> you had a filename with quotes in it.

Right. Looking around, I can find someone asking the Internet how to
escape the filename and not getting any response.

> This feature is inherently scraping text, and there's bound to be some
> ambiguities. I don't think it's worth worrying too much about unlikely
> filenames, as its the file content that is more likely to introduce
> unexpected characters.

Agreed. (s/its/it's/)

> So let's just go with the extra ":1" column specifier. We know this is
> supported everywhere, as git-jump's "grep" mode already uses it (and
> thus doesn't exhibit the same problem).
>
> The "merge" mode is mostly immune to this, as it only matches "<<<<<<<"
> conflict marker lines. It's possible of course to have a marker that
> says "foo 10:11" later in the line, but in practice these will only have
> branches and perhaps file names, so it's probably not worth worrying
> about (and fixing it would involve passing --column to the system grep,
> which may not be portable).

I suppose we could use `git grep --no-index` instead of `grep` for `git
jump merge`. Anyway, that's out of scope here.

> I also gave some thought as to whether we could put something more
> useful than "1" in the column field for diffs. In theory we could find

Heh. Yes, in theory everything is possible. Your approach makes sense.

> -               print "$file:$line: $1\n";
> +               print "$file:$line:1: $1\n";

Looks good to me and from my testing, this fixes the problem as
described.

Martin