Re: [RFC PATCH] Pass empty file to p4merge where no base is suitable.

From: Junio C Hamano <gitster@pobox.com>
Date: May 1, 2011, 21:54 UTC
Message-ID: <7v7haarsrd.fsf@alter.siamese.dyndns.org>
In-Reply-To: <BANLkTimf1q8JM46J-X1BCwQ+GaeWAgv75Q@mail.gmail.com>

Ciaran <ciaranj@gmail.com> writes:

Show 5 quoted lines

>> I suspect that you may be able to simply use "$BASE" for that, no?  It
>> will be cleaned up when cleanup_temp_files() is run anyway (warning: I do
>> not use mergetool, and I am writing this only from my cursory looking of
>> the script, so take this with a large grain of salt).
> I don't think so, the BASE file isn't created at-all in this scenario afaict.

Hmm, just like $BASE, your .no-base is not created at all in this scenario either, but you create it yourself in your patch, and because you picked a new filename for that temporary file, you also need to worry about cleaning it up.

Why can't that temporary file be "$BASE"? That is what I was asking. Then you would still create an empty file (but see *1*), and can rely on existing codepaths to clean it up.

IOW, wouldn't it be far simpler to turn the part you are patching into these three lines?

	$base_present || >"$BASE"
        "$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" "$MERGED"
        check_unchanged

Show 15 quoted lines

> diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
> index fb3f52b..7b2008f 100644
> --- a/git-mergetool--lib.sh
> +++ b/git-mergetool--lib.sh
> @@ -262,7 +262,9 @@ run_merge_tool () {
>  			if $base_present; then
>  				"$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" "$MERGED"
>  			else
> -				"$merge_tool_path" "$LOCAL" "$LOCAL" "$REMOTE" "$MERGED"
> +				: > "$GIT_DIR/.no_base"
> +				"$merge_tool_path" "$GIT_DIR/.no_base" "$LOCAL" "$REMOTE" "$MERGED"
> +				rm "$GIT_DIR/.no_base"
>  			fi
>  			check_unchanged
>  		else

[Footnote]

*1* It also may be worth considering to employ the "use either an empty
    file or use the common parts of merged files, whichever makes the
    merge simpler, as a phony base" technique found in git-merge-one-file.