Subject: Re: [PATCH] subtree: ignore merge.ff setting

From: Junio C Hamano <[email-masked]>
Date: Sun, 14 Nov 2021 10:38:24 -0800

"Thomas Koutcher via GitGitGadget" <[email-masked]> writes:

> From: Thomas Koutcher <[email-masked]>
>
> When `merge.ff` is set to `only` in .gitconfig, `git subtree pull` will
> fail with error `fatal: Not possible to fast-forward, aborting.`. This
> fix ignores the `merge.ff` setting when using `git merge` within subtree.

The first sentence is understandasble as a statement of fact.  There
is a small logic gap between it and the second sentence, calling the
change in the patch a "fix".  I think ", but the command does want
to make merges in these places." added after the first sentence
would fix it.

> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1139%2Fkoutcher%2Fsubtree-merge-ff-fix-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1139/koutcher/subtree-merge-ff-fix-v1
> Pull-Request: https://github.com/git/git/pull/1139
>
>  contrib/subtree/git-subtree.sh | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
> index 7f767b5c38f..de918d9fb05 100755
> --- a/contrib/subtree/git-subtree.sh
> +++ b/contrib/subtree/git-subtree.sh
> @@ -976,10 +976,10 @@ cmd_merge () {
>  
>  	if test -n "$arg_addmerge_message"
>  	then
> -		git merge -Xsubtree="$arg_prefix" \
> +		git -c merge.ff= merge -Xsubtree="$arg_prefix" \
>  			--message="$arg_addmerge_message" "$rev"
>  	else
> -		git merge -Xsubtree="$arg_prefix" $rev
> +		git -c merge.ff= merge -Xsubtree="$arg_prefix" $rev

And the natural way to override what is configured is to pass a
countermanding command line option, e.g. "git merge --ff" (or "git
merge --no-ff", if it wants to always create a merge even when
taking a change that is a descendant---I do not know the need of
"git subtree" well enough to tell), and that is easier to read than
"git -c ...".