v3, 5 partst4202-log: add tests for --merges=

revision.c, revision.h

diff --git a/revision.c b/revision.c
index 6399a04..c3c3dcc 100644
--- a/revision.c
+++ b/revision.c
@@ -1678,6 +1678,23 @@ static void add_message_grep(struct rev_info *revs, const char *pattern)
 	add_grep(revs, pattern, GREP_PATTERN_BODY);
 }
 
+int parse_merges_opt(struct rev_info *revs, const char *param)
+{
+	if (!strcmp(param, "show")) {
+		revs->min_parents = 0;
+		revs->max_parents = -1;
+	} else if (!strcmp(param, "only")) {
+		revs->min_parents = 2;
+		revs->max_parents = -1;
+	} else if (!strcmp(param, "hide")) {
+		revs->min_parents = 0;
+		revs->max_parents = 1;
+	} else {
+		return -1;
+	}
+	return 0;
+}
+
 static int handle_revision_opt(struct rev_info *revs, int argc, const char **argv,
 			       int *unkc, const char **unkv)
 {
@@ -1800,6 +1817,9 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 		revs->show_all = 1;
 	} else if (!strcmp(arg, "--remove-empty")) {
 		revs->remove_empty_trees = 1;
+	} else if (starts_with(arg, "--merges=")) {
+		if (parse_merges_opt(revs, arg + 9))
+			die("unknown option: %s", arg);
 	} else if (!strcmp(arg, "--merges")) {
 		revs->min_parents = 2;
 	} else if (!strcmp(arg, "--no-merges")) {
diff --git a/revision.h b/revision.h
index 0ea8b4e..f9df58c 100644
--- a/revision.h
+++ b/revision.h
@@ -240,6 +240,7 @@ extern int setup_revisions(int argc, const char **argv, struct rev_info *revs,
 extern void parse_revision_opt(struct rev_info *revs, struct parse_opt_ctx_t *ctx,
 			       const struct option *options,
 			       const char * const usagestr[]);
+extern int parse_merges_opt(struct rev_info *, const char *);
 #define REVARG_CANNOT_BE_FILENAME 01
 #define REVARG_COMMITTISH 02
 extern int handle_revision_arg(const char *arg, struct rev_info *revs,

diff --git a/builtin/log.c b/builtin/log.c
index dd8f3fc..c7a7aad 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -36,6 +36,7 @@ static int decoration_given;
 static int use_mailmap_config;
 static const char *fmt_patch_subject_prefix = "PATCH";
 static const char *fmt_pretty;
+static const char *log_merges;
 
 static const char * const builtin_log_usage[] = {
 	N_("git log [<options>] [<revision range>] [[--] <path>...]"),
@@ -386,6 +387,9 @@ static int git_log_config(const char *var, const char *value, void *cb)
 			decoration_style = 0; /* maybe warn? */
 		return 0;
 	}
+	if (!strcmp(var, "log.merges")) {
+		return git_config_string(&log_merges, var, value);
+	}
 	if (!strcmp(var, "log.showroot")) {
 		default_show_root = git_config_bool(var, value);
 		return 0;
@@ -628,6 +632,8 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 
 	init_revisions(&rev, prefix);
 	rev.always_show_header = 1;
+	if (log_merges && parse_merges_opt(&rev, log_merges))
+		die("unknown config value for log.merges: %s", log_merges);
 	memset(&opt, 0, sizeof(opt));
 	opt.def = "HEAD";
 	opt.revarg_opt = REVARG_COMMITTISH;

Documentation/git-log.txt, Documentation/rev-list-options.txt

diff --git a/Documentation/git-log.txt b/Documentation/git-log.txt
index 18bc716..e16f0f8 100644
--- a/Documentation/git-log.txt
+++ b/Documentation/git-log.txt
@@ -190,6 +190,9 @@ log.showRoot::
 	`git log -p` output would be shown without a diff attached.
 	The default is `true`.
 
+log.merges::
+    Default for `--merges=` option. Defaults to `show`.
+
 mailmap.*::
 	See linkgit:git-shortlog[1].
 
diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index f620ee4..88f152f 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -96,6 +96,23 @@ if it is part of the log message.
 --remove-empty::
 	Stop when a given path disappears from the tree.
 
+--merges={show|hide|only}::
+
+	Limit the output by type of commits.
+
+	`hide`;;
+		Hide merge commits from the output.
+
+	`only`;;
+		Hide non-merge commits from the output (i.e showing
+		only merge commits).
+
+	`show`;;
+		Do not hide either merge or non-merge commits. This
+		is primarily useful when the user has non-standard
+		setting of `log.merges` configuration variable that
+		needs to be overriden from the command line.
+
 --merges::
 	Print only merge commits. This is exactly the same as `--min-parents=2`.
 

diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 1b2e981..3edcd81 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -270,6 +270,35 @@ cat > expect <<\EOF
 * initial
 EOF
 
+test_expect_success 'setup merges=' '
+	git log --min-parents=2 --pretty=tformat:%s >expect_only &&
+	git log --max-parents=1 --pretty=tformat:%s >expect_hide &&
+	git log --min-parents=-1 --pretty=tformat:%s >expect_show
+'
+
+test_log_merges() {
+	expect=expect_$1
+	config=${2:+-c log.merges=$2}
+	option=${3:+--merges=$3}
+	option=${4:-$option}
+	test_expect_success "merges${config:+ $config}${option:+ $option}" "
+		git $config log $option --pretty=tformat:%s >actual &&
+		test_cmp $expect actual
+	"
+}
+
+states="show only hide"
+for c in '' $states
+do
+	for o in '' $states
+	do
+		test_log_merges ${o:-${c:-show}} "$c" "$o"
+	done
+done
+
+test_log_merges hide show '' --no-merges
+test_log_merges only hide '' '--merges --max-parents=2'
+
 test_expect_success 'log --graph with merge' '
 	git log --graph --date-order --pretty=tformat:%s |
 		sed "s/ *\$//" >actual &&

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index fbe5972..a75d7f5 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1406,7 +1406,7 @@ _git_ls_tree ()
 __git_log_common_options="
 	--not --all
 	--branches --tags --remotes
-	--first-parent --merges --no-merges
+	--first-parent --merges --merges= --no-merges
 	--max-count=
 	--max-age= --since= --after=
 	--min-age= --until= --before=
@@ -1451,7 +1451,11 @@ _git_log ()
 		__gitcomp "long short" "" "${cur##--decorate=}"
 		return
 		;;
-	--*)
+	--merges=*)
+		__gitcomp "show hide only" "" "${cur##--merges=}"
+		return
+		;;
+		--*)
 		__gitcomp "
 			$__git_log_common_options
 			$__git_log_shortlog_options
@@ -1861,6 +1865,10 @@ _git_config ()
 		__gitcomp "$__git_log_date_formats"
 		return
 		;;
+	log.merges)
+		__gitcomp "show hide only"
+		return
+		;;
 	sendemail.aliasesfiletype)
 		__gitcomp "mutt mailrc pine elm gnus"
 		return
@@ -2150,6 +2158,7 @@ _git_config ()
 		interactive.singlekey
 		log.date
 		log.decorate
+		log.merges
 		log.showroot
 		mailmap.file
 		man.

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index a75d7f5..83b2359 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1454,9 +1454,9 @@ _git_log ()
 	--merges=*)
 		__gitcomp "show hide only" "" "${cur##--merges=}"
 		return
 		;;
-		--*)
+	--*)
 		__gitcomp "
 			$__git_log_common_options
 			$__git_log_shortlog_options
 			$__git_log_gitk_options