Subject: Re: [PATCH] contrib/subtree: add repo url to commit messages

From: [email-masked] (David A. Greene)
Date: Sat, 21 May 2016 17:52:11 -0500

Mathias Nyman <[email-masked]> writes:

> For recalling where a subtree came from; git-subtree operations 'add'
> and 'pull', when called with the <repository> parameter add this to the
> commit message:
>     git-subtree-repo: <repo_url>

I am sorry it tooks a couple of months to respond.  I am finally coming
up for air at work.

What is the future intent of this?  I've toyed with the idea of adding
something like this either as commit message metadata or in .gitconfig
but every time I get ready to pull the trigger, I question what it will
be used for.

Having been using git-subtree in anger for a couple of years now, I
frequently pull subtree updates from multiple sources, so noting a
particular repository is not only mostly meaningless, it may actually be
misleading in that a quick perusal of the logs may lead one to think
commits were draw from fewer places than they actually were.

I don't think it would be a good idea, for example, to have git-subtree
use this information to auto-guess from where to pull future commits.
Again, I think that would be misleading behavior.

                         -David

> Other operations that don't have the <repository> information, like
> 'merge' and 'add' without <repository>, are unchanged. Users with such a
> workflow will continue to be on their own with the --message parameter,
> if they'd like to record where the subtree came from.
>
> Signed-off-by: Mathias Nyman <[email-masked]>
> Based-on-patch-by: Nicola Paolucci <[email-masked]>
> ---
>  contrib/subtree/git-subtree.sh | 73 ++++++++++++++++++++++++++++--------------
>  1 file changed, 49 insertions(+), 24 deletions(-)
>
> diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
> index 7a39b30..7cf73c0 100755
> --- a/contrib/subtree/git-subtree.sh
> +++ b/contrib/subtree/git-subtree.sh
> @@ -335,18 +335,21 @@ add_msg()
>  	dir="$1"
>  	latest_old="$2"
>  	latest_new="$3"
> +	repo="$4" # optional
>  	if [ -n "$message" ]; then
>  		commit_message="$message"
>  	else
>  		commit_message="Add '$dir/' from commit '$latest_new'"
>  	fi
> -	cat <<-EOF
> -		$commit_message
> -		
> -		git-subtree-dir: $dir
> -		git-subtree-mainline: $latest_old
> -		git-subtree-split: $latest_new
> -	EOF
> +	echo $commit_message
> +	echo
> +	echo git-subtree-dir: $dir
> +	echo git-subtree-mainline: $latest_old
> +	echo git-subtree-split: $latest_new
> +	if [ -n "$repo" ]; then
> +		repo_url=$(get_repository_url "$repo")
> +		echo "git-subtree-repo: $repo_url"
> +	fi
>  }
>  
>  add_squashed_msg()
> @@ -382,8 +385,9 @@ squash_msg()
>  	dir="$1"
>  	oldsub="$2"
>  	newsub="$3"
> +	repo="$4" # optional
>  	newsub_short=$(git rev-parse --short "$newsub")
> -	
> +
>  	if [ -n "$oldsub" ]; then
>  		oldsub_short=$(git rev-parse --short "$oldsub")
>  		echo "Squashed '$dir/' changes from $oldsub_short..$newsub_short"
> @@ -397,6 +401,10 @@ squash_msg()
>  	echo
>  	echo "git-subtree-dir: $dir"
>  	echo "git-subtree-split: $newsub"
> +	if [ -n "$repo" ]; then
> +		repo_url=$(get_repository_url "$repo")
> +		echo "git-subtree-repo: $repo_url"
> +	fi
>  }
>  
>  toptree_for_commit()
> @@ -440,12 +448,13 @@ new_squash_commit()
>  	old="$1"
>  	oldsub="$2"
>  	newsub="$3"
> +	repo="$4" # optional
>  	tree=$(toptree_for_commit $newsub) || exit $?
>  	if [ -n "$old" ]; then
> -		squash_msg "$dir" "$oldsub" "$newsub" | 
> +		squash_msg "$dir" "$oldsub" "$newsub" "$repo" |
>  			git commit-tree "$tree" -p "$old" || exit $?
>  	else
> -		squash_msg "$dir" "" "$newsub" |
> +		squash_msg "$dir" "" "$newsub" "$repo" |
>  			git commit-tree "$tree" || exit $?
>  	fi
>  }
> @@ -517,6 +526,16 @@ ensure_valid_ref_format()
>  	    die "'$1' does not look like a ref"
>  }
>  
> +get_repository_url()
> +{
> +	repo=$1
> +	repo_url=$(git config --get remote.$repo.url)
> +	if [ -z "$repo_url" ]; then
> +		repo_url=$repo
> +	fi
> +	echo $repo_url
> +}
> +
>  cmd_add()
>  {
>  	if [ -e "$dir" ]; then
> @@ -548,19 +567,18 @@ cmd_add()
>  cmd_add_repository()
>  {
>  	echo "git fetch" "$@"
> -	repository=$1
> +	repo=$1
>  	refspec=$2
>  	git fetch "$@" || exit $?
>  	revs=FETCH_HEAD
> -	set -- $revs
> +	set -- $revs $repo
>  	cmd_add_commit "$@"
>  }
>  
>  cmd_add_commit()
>  {
> -	revs=$(git rev-parse $default --revs-only "$@") || exit $?
> -	set -- $revs
> -	rev="$1"
> +	rev=$(git rev-parse $default --revs-only "$1") || exit $?
> +	repo="$2" # optional
>  	
>  	debug "Adding $dir as '$rev'..."
>  	git read-tree --prefix="$dir" $rev || exit $?
> @@ -575,12 +593,12 @@ cmd_add_commit()
>  	fi
>  	
>  	if [ -n "$squash" ]; then
> -		rev=$(new_squash_commit "" "" "$rev") || exit $?
> +		rev=$(new_squash_commit "" "" "$rev" "$repo") || exit $?
>  		commit=$(add_squashed_msg "$rev" "$dir" |
>  			 git commit-tree $tree $headp -p "$rev") || exit $?
>  	else
>  		revp=$(peel_committish "$rev") &&
> -		commit=$(add_msg "$dir" "$headrev" "$rev" |
> +		commit=$(add_msg "$dir" "$headrev" "$rev" "$repo" |
>  			 git commit-tree $tree $headp -p "$revp") || exit $?
>  	fi
>  	git reset "$commit" || exit $?
> @@ -609,7 +627,8 @@ cmd_split()
>  	else
>  		unrevs="$(find_existing_splits "$dir" "$revs")"
>  	fi
> -	
> +e
> +	rev="$1"
>  	# We can't restrict rev-list to only $dir here, because some of our
>  	# parents have the $dir contents the root, and those won't match.
>  	# (and rev-list --follow doesn't seem to solve this)
> @@ -683,15 +702,20 @@ cmd_split()
>  
>  cmd_merge()
>  {
> -	revs=$(git rev-parse $default --revs-only "$@") || exit $?
> +	revs=$(git rev-parse $default --revs-only "$1") || exit $?
>  	ensure_clean
> -	
>  	set -- $revs
>  	if [ $# -ne 1 ]; then
>  		die "You must provide exactly one revision.  Got: '$revs'"
>  	fi
> +	do_merge "$@"
> +}
> +
> +do_merge()
> +{
>  	rev="$1"
> -	
> +	repo="$2" # optional
> +
>  	if [ -n "$squash" ]; then
>  		first_split="$(find_latest_squash "$dir")"
>  		if [ -z "$first_split" ]; then
> @@ -704,7 +728,7 @@ cmd_merge()
>  			say "Subtree is already at commit $rev."
>  			exit 0
>  		fi
> -		new=$(new_squash_commit "$old" "$sub" "$rev") || exit $?
> +		new=$(new_squash_commit "$old" "$sub" "$rev" "$repo") || exit $?
>  		debug "New squash commit: $new"
>  		rev="$new"
>  	fi
> @@ -730,12 +754,13 @@ cmd_pull()
>  	if [ $# -ne 2 ]; then
>  	    die "You must provide <repository> <ref>"
>  	fi
> +	repo=$1
>  	ensure_clean
>  	ensure_valid_ref_format "$2"
>  	git fetch "$@" || exit $?
>  	revs=FETCH_HEAD
> -	set -- $revs
> -	cmd_merge "$@"
> +	set -- $revs $repo
> +	do_merge "$@"
>  }
>  
>  cmd_push()