[PATCH 3/5] diff-merges: implement log.diffMergesForce config

[Sergey Organov <sorganov@gmail.com>]

Force specified log format for -c, --cc, and --remerge-diff options
instead of their respective formats. The override is useful when some
external tool hard-codes diff for merges format option.

Using any of the above options twice or more will get back the
original meaning of the option no matter what configuration says.

Signed-off-by: Sergey Organov <sorganov@gmail.com>
---
 Documentation/config/log.txt | 11 +++++++++++
 builtin/log.c                |  2 ++
 diff-merges.c                | 32 ++++++++++++++++++++++++++------
 diff-merges.h                |  2 ++
 t/t4013-diff-various.sh      | 18 ++++++++++++++++++
 t/t9902-completion.sh        |  3 +++
 6 files changed, 62 insertions(+), 6 deletions(-)

diff --git a/Documentation/config/log.txt b/Documentation/config/log.txt
index 265a57312e58..7452c7fad638 100644
--- a/Documentation/config/log.txt
+++ b/Documentation/config/log.txt
@@ -43,6 +43,17 @@ log.diffMergesHide::
 log.diffMerges-m-imply-p::
 	`true` enables implication of `-p` by `-m`.
 
+log.diffMergesForce::
+	Use specified log format for -c, --cc, and --remerge-diff
+	options instead of their respective formats when the option
+	appears on the command line one time. See `--diff-merges` in
+	linkgit:git-log[1] for allowed values. Using 'off' or 'none'
+	disables the override (default).
++
+The override is useful when external tool hard-codes one of the above
+options. Using any of these options two (or more) times will get back
+the original meaning of the options.
+
 log.follow::
 	If `true`, `git log` will act as if the `--follow` option was used when
 	a single <path> is given.  This has the same limitations as `--follow`,
diff --git a/builtin/log.c b/builtin/log.c
index 332b5e478cc5..1e8d0a2545a9 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -585,6 +585,8 @@ static int git_log_config(const char *var, const char *value, void *cb)
 		return diff_merges_hide_config(git_config_bool(var, value));
 	if (!strcmp(var, "log.diffmerges-m-imply-p"))
 		return diff_merges_m_imply_p_config(git_config_bool(var, value));
+	if (!strcmp(var, "log.diffmergesforce"))
+		return diff_merges_force_config(value);
 	if (!strcmp(var, "log.showroot")) {
 		default_show_root = git_config_bool(var, value);
 		return 0;
diff --git a/diff-merges.c b/diff-merges.c
index 1fbf476d378e..cedd7652bf42 100644
--- a/diff-merges.c
+++ b/diff-merges.c
@@ -6,6 +6,7 @@ typedef void (*diff_merges_setup_func_t)(struct rev_info *);
 static void set_separate(struct rev_info *revs);
 
 static diff_merges_setup_func_t set_to_default = set_separate;
+static diff_merges_setup_func_t force_func = NULL;
 static int suppress_m_parsing;
 static int hide = 0;
 static int m_imply_p = 0;
@@ -150,6 +151,21 @@ int diff_merges_m_imply_p_config(int on)
 	return 0;
 }
 
+int diff_merges_force_config(const char *value)
+{
+	diff_merges_setup_func_t func = func_by_opt(value);
+
+	if (!func)
+		return -1;
+
+	if (func == set_none)
+		force_func = NULL;
+	else if (func != set_hide && func != set_no_hide)
+		force_func = func;
+
+	return 0;
+}
+
 void diff_merges_suppress_m_parsing(void)
 {
 	suppress_m_parsing = 1;
@@ -160,20 +176,18 @@ int diff_merges_parse_opts(struct rev_info *revs, const char **argv)
 	int argcount = 1;
 	const char *optarg;
 	const char *arg = argv[0];
+	diff_merges_setup_func_t set_func = NULL;
 
 	if (!suppress_m_parsing && !strcmp(arg, "-m")) {
 		set_to_default(revs);
 		set_hide(revs);
 		revs->merges_imply_patch = m_imply_p;
 	} else if (!strcmp(arg, "-c")) {
-		set_combined(revs);
-		revs->merges_imply_patch = 1;
+		set_func = set_combined;
 	} else if (!strcmp(arg, "--cc")) {
-		set_dense_combined(revs);
-		revs->merges_imply_patch = 1;
+		set_func = set_dense_combined;
 	} else if (!strcmp(arg, "--remerge-diff")) {
-		set_remerge_diff(revs);
-		revs->merges_imply_patch = 1;
+		set_func = set_remerge_diff;
 	} else if (!strcmp(arg, "--no-diff-merges")) {
 		set_none(revs);
 	} else if (!strcmp(arg, "--combined-all-paths")) {
@@ -183,6 +197,12 @@ int diff_merges_parse_opts(struct rev_info *revs, const char **argv)
 	} else
 		return 0;
 
+	if (set_func != NULL) {
+		(force_func ? force_func : set_func)(revs);
+		force_func = NULL;
+		revs->merges_imply_patch = 1;
+	}
+
 	revs->explicit_diff_merges = 1;
 	return argcount;
 }
diff --git a/diff-merges.h b/diff-merges.h
index 9f0b3901fe82..6ef0cc87bb2a 100644
--- a/diff-merges.h
+++ b/diff-merges.h
@@ -15,6 +15,8 @@ int diff_merges_hide_config(int hide);
 
 int diff_merges_m_imply_p_config(int on);
 
+int diff_merges_force_config(const char *value);
+
 void diff_merges_suppress_m_parsing(void);
 
 int diff_merges_parse_opts(struct rev_info *revs, const char **argv);
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 1789dd6063c5..8a90d2dac360 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -557,6 +557,24 @@ test_expect_success 'git config log.diffMerges-m-imply-p has proper effect' '
 	test_cmp expected actual
 '
 
+test_expect_success 'git config log.diffMergesForce has proper effect' '
+	git log -m -p master >result &&
+	process_diffs result >expected &&
+	test_config log.diffMergesForce on &&
+	git log --cc master >result &&
+	process_diffs result >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'git config log.diffMergesForce override by duplicate' '
+	git log --cc master >result &&
+	process_diffs result >expected &&
+	test_config log.diffMergesForce on &&
+	git log --cc --cc master >result &&
+	process_diffs result >actual &&
+	test_cmp expected actual
+'
+
 # -m in "git diff-index" means "match missing", that differs
 # from its meaning in "git diff". Let's check it in diff-index.
 # The line in the output for removed file should disappear when
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 26a7e4ff877c..411e08b2fa1b 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -2498,6 +2498,7 @@ test_expect_success 'git config - variable name' '
 	log.decorate Z
 	log.diffMerges Z
 	log.diffMergesHide Z
+	log.diffMergesForce Z
 	log.diffMerges-m-imply-p Z
 	EOF
 '
@@ -2528,6 +2529,7 @@ test_expect_success 'git -c - variable name' '
 	log.decorate=Z
 	log.diffMerges=Z
 	log.diffMergesHide=Z
+	log.diffMergesForce=Z
 	log.diffMerges-m-imply-p=Z
 	EOF
 '
@@ -2552,6 +2554,7 @@ test_expect_success 'git clone --config= - variable name' '
 	log.decorate=Z
 	log.diffMerges=Z
 	log.diffMergesHide=Z
+	log.diffMergesForce=Z
 	log.diffMerges-m-imply-p=Z
 	EOF
 '
-- 
2.37.3.526.g5f84746cb16b