Merge branch 'jk/notes-merge-config'

"git notes merge" can be told with "--strategy=<how>" option how to
automatically handle conflicts; this can now be configured by
setting notes.mergeStrategy configuration variable.

* jk/notes-merge-config:
  notes: teach git-notes about notes.<name>.mergeStrategy option
  notes: add notes.mergeStrategy option to select default strategy
  notes: add tests for --commit/--abort/--strategy exclusivity
  notes: extract parse_notes_merge_strategy to notes-utils
  notes: extract enum notes_merge_strategy to notes-utils.h
  notes: document cat_sort_uniq rewriteMode

8 files changed, 187 insertions, 25 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index f5d15fff3e..4400a1c9d8 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1942,6 +1942,18 @@ mergetool.writeToTemp::
 mergetool.prompt::
 	Prompt before each invocation of the merge resolution program.
 
+notes.mergeStrategy::
+	Which merge strategy to choose by default when resolving notes
+	conflicts.  Must be one of `manual`, `ours`, `theirs`, `union`, or
+	`cat_sort_uniq`.  Defaults to `manual`.  See "NOTES MERGE STRATEGIES"
+	section of linkgit:git-notes[1] for more information on each strategy.
+
+notes.<name>.mergeStrategy::
+	Which merge strategy to choose when doing a notes merge into
+	refs/notes/<name>.  This overrides the more general
+	"notes.mergeStrategy".  See the "NOTES MERGE STRATEGIES" section in
+	linkgit:git-notes[1] for more information on the available strategies.
+
 notes.displayRef::
 	The (fully qualified) refname from which to show notes when
 	showing commit messages.  The value of this variable can be set
@@ -1970,8 +1982,8 @@ notes.rewriteMode::
 	When copying notes during a rewrite (see the
 	"notes.rewrite.<command>" option), determines what to do if
 	the target commit already has a note.  Must be one of
-	`overwrite`, `concatenate`, or `ignore`.  Defaults to
-	`concatenate`.
+	`overwrite`, `concatenate`, `cat_sort_uniq`, or `ignore`.
+	Defaults to `concatenate`.
 +
 This setting can be overridden with the `GIT_NOTES_REWRITE_MODE`
 environment variable.
diff --git a/Documentation/git-notes.txt b/Documentation/git-notes.txt
index 851518d531..a9a916f360 100644
--- a/Documentation/git-notes.txt
+++ b/Documentation/git-notes.txt
@@ -101,7 +101,7 @@ merge::
 	any) into the current notes ref (called "local").
 +
 If conflicts arise and a strategy for automatically resolving
-conflicting notes (see the -s/--strategy option) is not given,
+conflicting notes (see the "NOTES MERGE STRATEGIES" section) is not given,
 the "manual" resolver is used. This resolver checks out the
 conflicting notes in a special worktree (`.git/NOTES_MERGE_WORKTREE`),
 and instructs the user to manually resolve the conflicts there.
@@ -183,6 +183,7 @@ OPTIONS
 	When merging notes, resolve notes conflicts using the given
 	strategy. The following strategies are recognized: "manual"
 	(default), "ours", "theirs", "union" and "cat_sort_uniq".
+	This option overrides the "notes.mergeStrategy" configuration setting.
 	See the "NOTES MERGE STRATEGIES" section below for more
 	information on each notes merge strategy.
 
@@ -247,6 +248,9 @@ When done, the user can either finalize the merge with
 'git notes merge --commit', or abort the merge with
 'git notes merge --abort'.
 
+Users may select an automated merge strategy from among the following using
+either -s/--strategy option or configuring notes.mergeStrategy accordingly:
+
 "ours" automatically resolves conflicting notes in favor of the local
 version (i.e. the current notes ref).
 
@@ -310,6 +314,20 @@ core.notesRef::
 	This setting can be overridden through the environment and
 	command line.
 
+notes.mergeStrategy::
+	Which merge strategy to choose by default when resolving notes
+	conflicts.  Must be one of `manual`, `ours`, `theirs`, `union`, or
+	`cat_sort_uniq`.  Defaults to `manual`.  See "NOTES MERGE STRATEGIES"
+	section above for more information on each strategy.
++
+This setting can be overridden by passing the `--strategy` option.
+
+notes.<name>.mergeStrategy::
+	Which merge strategy to choose when doing a notes merge into
+	refs/notes/<name>.  This overrides the more general
+	"notes.mergeStrategy".  See the "NOTES MERGE STRATEGIES" section above
+	for more information on each available strategy.
+
 notes.displayRef::
 	Which ref (or refs, if a glob or specified more than once), in
 	addition to the default set by `core.notesRef` or
@@ -331,7 +349,8 @@ environment variable.
 notes.rewriteMode::
 	When copying notes during a rewrite, what to do if the target
 	commit already has a note.  Must be one of `overwrite`,
-	`concatenate`, and `ignore`.  Defaults to `concatenate`.
+	`concatenate`, `cat_sort_uniq`, or `ignore`.  Defaults to
+	`concatenate`.
 +
 This setting can be overridden with the `GIT_NOTES_REWRITE_MODE`
 environment variable.
@@ -368,7 +387,7 @@ does not match any refs is silently ignored.
 'GIT_NOTES_REWRITE_MODE'::
 	When copying notes during a rewrite, what to do if the target
 	commit already has a note.
-	Must be one of `overwrite`, `concatenate`, and `ignore`.
+	Must be one of `overwrite`, `concatenate`, `cat_sort_uniq`, or `ignore`.
 	This overrides the `core.rewriteMode` setting.
 
 'GIT_NOTES_REWRITE_REF'::
diff --git a/builtin/notes.c b/builtin/notes.c
index 0423480827..3608c64785 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -738,6 +738,19 @@ static int merge_commit(struct notes_merge_options *o)
 	return ret;
 }
 
+static int git_config_get_notes_strategy(const char *key,
+					 enum notes_merge_strategy *strategy)
+{
+	const char *value;
+
+	if (git_config_get_string_const(key, &value))
+		return 1;
+	if (parse_notes_merge_strategy(value, strategy))
+		git_die_config(key, "unknown notes merge strategy %s", value);
+
+	return 0;
+}
+
 static int merge(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf remote_ref = STRBUF_INIT, msg = STRBUF_INIT;
@@ -796,24 +809,28 @@ static int merge(int argc, const char **argv, const char *prefix)
 	expand_notes_ref(&remote_ref);
 	o.remote_ref = remote_ref.buf;
 
+	t = init_notes_check("merge");
+
 	if (strategy) {
-		if (!strcmp(strategy, "manual"))
-			o.strategy = NOTES_MERGE_RESOLVE_MANUAL;
-		else if (!strcmp(strategy, "ours"))
-			o.strategy = NOTES_MERGE_RESOLVE_OURS;
-		else if (!strcmp(strategy, "theirs"))
-			o.strategy = NOTES_MERGE_RESOLVE_THEIRS;
-		else if (!strcmp(strategy, "union"))
-			o.strategy = NOTES_MERGE_RESOLVE_UNION;
-		else if (!strcmp(strategy, "cat_sort_uniq"))
-			o.strategy = NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ;
-		else {
+		if (parse_notes_merge_strategy(strategy, &o.strategy)) {
 			error("Unknown -s/--strategy: %s", strategy);
 			usage_with_options(git_notes_merge_usage, options);
 		}
-	}
+	} else {
+		struct strbuf merge_key = STRBUF_INIT;
+		const char *short_ref = NULL;
 
-	t = init_notes_check("merge");
+		if (!skip_prefix(o.local_ref, "refs/notes/", &short_ref))
+			die("BUG: local ref %s is outside of refs/notes/",
+			    o.local_ref);
+
+		strbuf_addf(&merge_key, "notes.%s.mergeStrategy", short_ref);
+
+		if (git_config_get_notes_strategy(merge_key.buf, &o.strategy))
+			git_config_get_notes_strategy("notes.mergeStrategy", &o.strategy);
+
+		strbuf_release(&merge_key);
+	}
 
 	strbuf_addf(&msg, "notes: Merged notes from %s into %s",
 		    remote_ref.buf, default_notes_ref());
diff --git a/notes-merge.h b/notes-merge.h
index 1d01f6aacf..0d890563b5 100644
--- a/notes-merge.h
+++ b/notes-merge.h
@@ -1,6 +1,8 @@
 #ifndef NOTES_MERGE_H
 #define NOTES_MERGE_H
 
+#include "notes-utils.h"
+
 #define NOTES_MERGE_WORKTREE "NOTES_MERGE_WORKTREE"
 
 enum notes_merge_verbosity {
@@ -13,13 +15,7 @@ struct notes_merge_options {
 	const char *remote_ref;
 	struct strbuf commit_msg;
 	int verbosity;
-	enum {
-		NOTES_MERGE_RESOLVE_MANUAL = 0,
-		NOTES_MERGE_RESOLVE_OURS,
-		NOTES_MERGE_RESOLVE_THEIRS,
-		NOTES_MERGE_RESOLVE_UNION,
-		NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ
-	} strategy;
+	enum notes_merge_strategy strategy;
 	unsigned has_worktree:1;
 };
 
diff --git a/notes-utils.c b/notes-utils.c
index ccbf0737a3..299e34bccc 100644
--- a/notes-utils.c
+++ b/notes-utils.c
@@ -54,6 +54,24 @@ void commit_notes(struct notes_tree *t, const char *msg)
 	strbuf_release(&buf);
 }
 
+int parse_notes_merge_strategy(const char *v, enum notes_merge_strategy *s)
+{
+	if (!strcmp(v, "manual"))
+		*s = NOTES_MERGE_RESOLVE_MANUAL;
+	else if (!strcmp(v, "ours"))
+		*s = NOTES_MERGE_RESOLVE_OURS;
+	else if (!strcmp(v, "theirs"))
+		*s = NOTES_MERGE_RESOLVE_THEIRS;
+	else if (!strcmp(v, "union"))
+		*s = NOTES_MERGE_RESOLVE_UNION;
+	else if (!strcmp(v, "cat_sort_uniq"))
+		*s = NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ;
+	else
+		return -1;
+
+	return 0;
+}
+
 static combine_notes_fn parse_combine_notes_fn(const char *v)
 {
 	if (!strcasecmp(v, "overwrite"))
diff --git a/notes-utils.h b/notes-utils.h
index 890ddb33e1..fa538e1d95 100644
--- a/notes-utils.h
+++ b/notes-utils.h
@@ -19,6 +19,14 @@ void create_notes_commit(struct notes_tree *t, struct commit_list *parents,
 
 void commit_notes(struct notes_tree *t, const char *msg);
 
+enum notes_merge_strategy {
+		NOTES_MERGE_RESOLVE_MANUAL = 0,
+		NOTES_MERGE_RESOLVE_OURS,
+		NOTES_MERGE_RESOLVE_THEIRS,
+		NOTES_MERGE_RESOLVE_UNION,
+		NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ
+};
+
 struct notes_rewrite_cfg {
 	struct notes_tree **trees;
 	const char *cmd;
@@ -29,6 +37,7 @@ struct notes_rewrite_cfg {
 	int mode_from_env;
 };
 
+int parse_notes_merge_strategy(const char *v, enum notes_merge_strategy *s);
 struct notes_rewrite_cfg *init_copy_notes_for_rewrite(const char *cmd);
 int copy_note_for_rewrite(struct notes_rewrite_cfg *c,
 			  const unsigned char *from_obj, const unsigned char *to_obj);
diff --git a/t/t3309-notes-merge-auto-resolve.sh b/t/t3309-notes-merge-auto-resolve.sh
index 461fd84755..14c2adf970 100755
--- a/t/t3309-notes-merge-auto-resolve.sh
+++ b/t/t3309-notes-merge-auto-resolve.sh
@@ -298,6 +298,13 @@ test_expect_success 'merge z into y with invalid strategy => Fail/No changes' '
 	verify_notes y y
 '
 
+test_expect_success 'merge z into y with invalid configuration option => Fail/No changes' '
+	git config core.notesRef refs/notes/y &&
+	test_must_fail git -c notes.mergeStrategy="foo" notes merge z &&
+	# Verify no changes (y)
+	verify_notes y y
+'
+
 cat <<EOF | sort >expect_notes_ours
 68b8630d25516028bed862719855b3d6768d7833 $commit_sha15
 5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
@@ -365,6 +372,28 @@ test_expect_success 'reset to pre-merge state (y)' '
 	verify_notes y y
 '
 
+test_expect_success 'merge z into y with "ours" configuration option => Non-conflicting 3-way merge' '
+	git -c notes.mergeStrategy="ours" notes merge z &&
+	verify_notes y ours
+'
+
+test_expect_success 'reset to pre-merge state (y)' '
+	git update-ref refs/notes/y refs/notes/y^1 &&
+	# Verify pre-merge state
+	verify_notes y y
+'
+
+test_expect_success 'merge z into y with "ours" per-ref configuration option => Non-conflicting 3-way merge' '
+	git -c notes.y.mergeStrategy="ours" notes merge z &&
+	verify_notes y ours
+'
+
+test_expect_success 'reset to pre-merge state (y)' '
+	git update-ref refs/notes/y refs/notes/y^1 &&
+	# Verify pre-merge state
+	verify_notes y y
+'
+
 cat <<EOF | sort >expect_notes_theirs
 9b4b2c61f0615412da3c10f98ff85b57c04ec765 $commit_sha15
 5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
@@ -432,6 +461,17 @@ test_expect_success 'reset to pre-merge state (y)' '
 	verify_notes y y
 '
 
+test_expect_success 'merge z into y with "theirs" strategy overriding configuration option "ours" => Non-conflicting 3-way merge' '
+	git -c notes.mergeStrategy="ours" notes merge --strategy=theirs z &&
+	verify_notes y theirs
+'
+
+test_expect_success 'reset to pre-merge state (y)' '
+	git update-ref refs/notes/y refs/notes/y^1 &&
+	# Verify pre-merge state
+	verify_notes y y
+'
+
 cat <<EOF | sort >expect_notes_union
 7c4e546efd0fe939f876beb262ece02797880b54 $commit_sha15
 5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
@@ -505,6 +545,34 @@ test_expect_success 'reset to pre-merge state (y)' '
 	verify_notes y y
 '
 
+test_expect_success 'merge z into y with "union" strategy overriding per-ref configuration => Non-conflicting 3-way merge' '
+	git -c notes.y.mergeStrategy="theirs" notes merge --strategy=union z &&
+	verify_notes y union
+'
+
+test_expect_success 'reset to pre-merge state (y)' '
+	git update-ref refs/notes/y refs/notes/y^1 &&
+	# Verify pre-merge state
+	verify_notes y y
+'
+
+test_expect_success 'merge z into y with "union" per-ref overriding general configuration => Non-conflicting 3-way merge' '
+	git -c notes.y.mergeStrategy="union" -c notes.mergeStrategy="theirs" notes merge z &&
+	verify_notes y union
+'
+
+test_expect_success 'reset to pre-merge state (y)' '
+	git update-ref refs/notes/y refs/notes/y^1 &&
+	# Verify pre-merge state
+	verify_notes y y
+'
+
+test_expect_success 'merge z into y with "manual" per-ref only checks specific ref configuration => Conflicting 3-way merge' '
+	test_must_fail git -c notes.z.mergeStrategy="union" notes merge z &&
+	git notes merge --abort &&
+	verify_notes y y
+'
+
 cat <<EOF | sort >expect_notes_union2
 d682107b8bf7a7aea1e537a8d5cb6a12b60135f1 $commit_sha15
 5de7ea7ad4f47e7ff91989fb82234634730f75df $commit_sha14
@@ -644,4 +712,15 @@ test_expect_success 'merge y into z with "cat_sort_uniq" strategy => Non-conflic
 	verify_notes z cat_sort_uniq
 '
 
+test_expect_success 'reset to pre-merge state (z)' '
+	git update-ref refs/notes/z refs/notes/z^1 &&
+	# Verify pre-merge state
+	verify_notes z z
+'
+
+test_expect_success 'merge y into z with "cat_sort_uniq" strategy configuration option => Non-conflicting 3-way merge' '
+	git -c notes.mergeStrategy="cat_sort_uniq" notes merge y &&
+	verify_notes z cat_sort_uniq
+'
+
 test_done
diff --git a/t/t3310-notes-merge-manual-resolve.sh b/t/t3310-notes-merge-manual-resolve.sh
index 195bb97f85..d5572121da 100755
--- a/t/t3310-notes-merge-manual-resolve.sh
+++ b/t/t3310-notes-merge-manual-resolve.sh
@@ -314,6 +314,18 @@ y and z notes on 1st commit
 
 EOF
 
+test_expect_success 'do not allow mixing --commit and --abort' '
+	test_must_fail git notes merge --commit --abort
+'
+
+test_expect_success 'do not allow mixing --commit and --strategy' '
+	test_must_fail git notes merge --commit --strategy theirs
+'
+
+test_expect_success 'do not allow mixing --abort and --strategy' '
+	test_must_fail git notes merge --abort --strategy theirs
+'
+
 test_expect_success 'finalize conflicting merge (z => m)' '
 	# Resolve conflicts and finalize merge
 	cat >.git/NOTES_MERGE_WORKTREE/$commit_sha1 <<EOF &&