Re: [PATCH v4] Add default merge options for all branches

> Add support for branch.*.mergeoptions for setting default options for
> all branches.  This new value shares semantics with the existing
> branch.<name>.mergeoptions variable. If a branch specific value is
> found, that value will be used.
> 
> The need for this arises from the fact that there is currently not an
> easy way to set merge options for all branches. Instead of having to
> specify merge options for each individual branch there should be a way
> to set defaults for all branches and then override a specific branch's
> options.
> 
> In order to facilitate future features centered around this new
> "globlike" syntax a new struct has been created to keep track of the
> branch.*.* options.  Currently it only supports branch.*.mergeoptions,
> but can be easily modified in the future to support other branch
> specific options as well. The mechanism will "vote" on specific-"ness"
> of the configuration key and ultimately only use the most specific
> options.  This is not cumulative but overriding.
> 
> Signed-off-by: Michael Grubb <devel@dailyvoid.com>
> ---
>  Documentation/git-merge.txt |    3 +
>  builtin/merge.c             |   90 +++++++++++++++++++++++++++++++++---------
>  t/t7600-merge.sh            |   39 ++++++++++++++++++
>  3 files changed, 112 insertions(+), 20 deletions(-)
> 
> diff --git a/Documentation/git-merge.txt b/Documentation/git-merge.txt
> index e2e6aba..eaab3e4 100644
> --- a/Documentation/git-merge.txt
> +++ b/Documentation/git-merge.txt
> @@ -307,6 +307,9 @@ branch.<name>.mergeoptions::
>  	Sets default options for merging into branch <name>. The syntax and
>  	supported options are the same as those of 'git merge', but option
>  	values containing whitespace characters are currently not supported.
> +	The special value '*' for <name> may be used to configure default
> +	options for all branches.  Values for specific branch names will
> +	override the this default.
>  
>  SEE ALSO
>  --------
> diff --git a/builtin/merge.c b/builtin/merge.c
> index d171c63..d6ce85e 100644
> --- a/builtin/merge.c
> +++ b/builtin/merge.c
> @@ -32,6 +32,21 @@
>  #define NO_FAST_FORWARD (1<<2)
>  #define NO_TRIVIAL      (1<<3)
>  
> +/* This is for branch.<foo>. blocks
> + * the vote member holds a value between
> + * 0.0 and 1.0 which measures how closely
> + * a branch name matches the key member.
> + * where branch.*.mergeoptions would be 0.1 and
> + * branch.<name>.mergeoptions would be 1.0
> + * Also it is called vote because I couldn't come
> + * up with a better name.
> + */
> +struct merge_options_cb {
> +	char *key;
> +	char *value;
> +	float vote;
> +};
> +
>  struct strategy {
>  	const char *name;
>  	unsigned attr;
> @@ -503,28 +518,60 @@ cleanup:
>  	strbuf_release(&bname);
>  }
>  
> -static int git_merge_config(const char *k, const char *v, void *cb)
> +static void parse_git_merge_options(const char *k, const char *v,
> +			void *cb)
>  {
> -	if (branch && !prefixcmp(k, "branch.") &&
> -		!prefixcmp(k + 7, branch) &&
> -		!strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
> -		const char **argv;
> -		int argc;
> -		char *buf;
> -
> -		buf = xstrdup(v);
> -		argc = split_cmdline(buf, &argv);
> -		if (argc < 0)
> -			die(_("Bad branch.%s.mergeoptions string: %s"), branch,
> -			    split_cmdline_strerror(argc));
> -		argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
> -		memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
> -		argc++;
> -		parse_options(argc, argv, NULL, builtin_merge_options,
> -			      builtin_merge_usage, 0);
> -		free(buf);
> +	struct merge_options_cb *merge_options = cb;
> +	int changed = 0;
> +
> +	/* We only handle mergeoptions for now */
> +	if (suffixcmp(k, ".mergeoptions"))
> +		return;
> +
> +	if (!prefixcmp(k, "branch.*") && merge_options->vote <= 0.1 ) {
> +		merge_options->vote = 0.1;
> +		changed = 1;
> +	} else if (branch && !prefixcmp(k, "branch.") &&
> +				!prefixcmp(k + 7, branch) &&
> +				merge_options->vote < 1.0) {
> +		merge_options->vote = 1.0;
> +		changed = 1;
>  	}
>  
> +	if (changed) {
> +		merge_options->key = (char *)k;
> +		merge_options->value = (char *)v;
> +	}
> +}
> +
> +static void apply_merge_options(struct merge_options_cb *opts)
> +{
> +	const char **argv;
> +	int argc;
> +	char *buf;
> +
> +	if ( opts == NULL )
> +		return;
> +
> +	buf = xstrdup(opts->value);
> +	argc = split_cmdline(buf, &argv);
> +	if (argc < 0)
> +		die(_("Bad %s string: %s"), 
> +			opts->key, split_cmdline_strerror(argc));
> +
> +	argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
> +	memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
> +	argc++;
> +	parse_options(argc, argv, NULL, builtin_merge_options,
> +			  builtin_merge_usage, 0);
> +	free(buf);
> +}
> +
> +static int git_merge_config(const char *k, const char *v, void *cb)
> +{
> +	if (cb != NULL && branch && !prefixcmp(k, "branch."))
> +		parse_git_merge_options(k, v, cb);
> +
>  	if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
>  		show_diffstat = git_config_bool(k, v);
>  	else if (!strcmp(k, "pull.twohead"))
> @@ -987,6 +1034,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
>  	const char *head_arg;
>  	int flag, head_invalid = 0, i;
>  	int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
> +	struct merge_options_cb merge_options = {NULL, NULL, 0.0};
>  	struct commit_list *common = NULL;
>  	const char *best_strategy = NULL, *wt_strategy = NULL;
>  	struct commit_list **remotes = &remoteheads;
> @@ -1004,7 +1052,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
>  	if (is_null_sha1(head))
>  		head_invalid = 1;
>  
> -	git_config(git_merge_config, NULL);
> +	git_config(git_merge_config, &merge_options);
> +	if (merge_options.key != NULL && merge_options.value != NULL)
> +		apply_merge_options(&merge_options);
>  
>  	/* for color.ui */
>  	if (diff_use_color_default == -1)
> diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
> index e84e822..5b1f8e1 100755
> --- a/t/t7600-merge.sh
> +++ b/t/t7600-merge.sh
> @@ -415,6 +415,45 @@ test_expect_success 'merge c0 with c1 (no-ff)' '
>  
>  test_debug 'git log --graph --decorate --oneline --all'
>  
> +test_expect_success 'merge c0 with c1 (default no-ff)' '
> +	git reset --hard c0 &&
> +	test_might_fail git config --unset branch.master.mergeoptions &&
> +	git config "branch.*.mergeoptions" "--no-ff" &&
> +	test_tick &&
> +	git merge c1 &&
> +	git config --remove-section "branch.*" &&
> +	verify_merge file result.1 &&
> +	verify_parents $c0 $c1
> +'
> +
> +test_debug 'git log --graph --decorate --oneline --all'
> +
> +test_expect_success 'combine branch.*.mergeoptions with branch.x.mergeoptions' '
> +	git reset --hard c0 &&
> +	test_might_fail git config --remove-section branch.master &&
> +	git config "branch.*.mergeoptions" "--no-ff" &&
> +	git config branch.master.mergeoptions "--ff" &&
> +	test_tick &&
> +	git merge c1 &&
> +	git config --remove-section "branch.*" &&
> +	verify_merge file result.1 &&
> +	verify_parents "$c0"
> +'
> +
> +test_expect_success 'reverse branch.x.mergeoptions with branch.*.mergeoptions' '
> +	git reset --hard c0 &&
> +	test_might_fail git config --remove-section branch.master &&
> +	git config branch.master.mergeoptions "--ff" &&
> +	git config "branch.*.mergeoptions" "--no-ff" &&
> +	test_tick &&
> +	git merge c1 &&
> +	git config --remove-section "branch.*" &&
> +	verify_merge file result.1 &&
> +	verify_parents "$c0"
> +'
> +
> +test_debug 'git log --graph --decorate --oneline --all'
> +
>  test_expect_success 'combining --squash and --no-ff is refused' '
>  	test_must_fail git merge --squash --no-ff c1 &&
>  	test_must_fail git merge --no-ff --squash c1