format-patch: add format.coverLetter configuration variable

Also, add a new option: 'auto', so if there's more than one patch, the
cover letter is generated, otherwise it's not.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1096,6 +1096,11 @@ format.signoff::
     the rights to submit this work under the same open source license.
     Please see the 'SubmittingPatches' document for further discussion.
 
+format.coverLetter::
+	A boolean that controls whether to generate a cover-letter when
+	format-patch is invoked, but in addition can be set to "auto", to
+	generate a cover-letter only when there's more than one patch.
+
 filter.<driver>.clean::
 	The command which is used to convert the content of a worktree
 	file to a blob upon checkin.  See linkgit:gitattributes[5] for

Documentation/git-format-patch.txt

@@ -20,7 +20,7 @@ SYNOPSIS
 		   [--ignore-if-in-upstream]
 		   [--subject-prefix=Subject-Prefix] [(--reroll-count|-v) <n>]
 		   [--to=<email>] [--cc=<email>]
-		   [--cover-letter] [--quiet] [--notes[=<ref>]]
+		   [--[no-]cover-letter] [--quiet] [--notes[=<ref>]]
 		   [<common diff options>]
 		   [ <since> | <revision range> ]
 
@@ -195,7 +195,7 @@ will want to ensure that threading is disabled for `git send-email`.
 	`Cc:`, and custom) headers added so far from config or command
 	line.
 
---cover-letter::
+--[no-]cover-letter::
 	In addition to the patches, generate a cover letter file
 	containing the shortlog and the overall diffstat.  You can
 	fill in a description in the file before sending it out.
@@ -260,6 +260,7 @@ attachments, and sign off patches with configuration variables.
 	cc = <email>
 	attach [ = mime-boundary-string ]
 	signoff = true
+	coverletter = auto
 ------------
 
 

builtin/log.c

@@ -622,6 +622,14 @@ static void add_header(const char *value)
 static int thread;
 static int do_signoff;
 static const char *signature = git_version_string;
+static int config_cover_letter;
+
+enum {
+	COVER_UNSET,
+	COVER_OFF,
+	COVER_ON,
+	COVER_AUTO
+};
 
 static int git_format_config(const char *var, const char *value, void *cb)
 {
@@ -683,6 +691,14 @@ static int git_format_config(const char *var, const char *value, void *cb)
 	}
 	if (!strcmp(var, "format.signature"))
 		return git_config_string(&signature, var, value);
+	if (!strcmp(var, "format.coverletter")) {
+		if (value && !strcasecmp(value, "auto")) {
+			config_cover_letter = COVER_AUTO;
+			return 0;
+		}
+		config_cover_letter = git_config_bool(var, value) ? COVER_ON : COVER_OFF;
+		return 0;
+	}
 
 	return git_log_config(var, value, cb);
 }
@@ -1074,7 +1090,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	int start_number = -1;
 	int just_numbers = 0;
 	int ignore_if_in_upstream = 0;
-	int cover_letter = 0;
+	int cover_letter = -1;
 	int boundary_count = 0;
 	int no_binary_diff = 0;
 	struct commit *origin = NULL, *head = NULL;
@@ -1309,11 +1325,6 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	 */
 	rev.show_root_diff = 1;
 
-	if (cover_letter) {
-		if (!branch_name)
-			branch_name = find_branch_name(&rev);
-	}
-
 	if (ignore_if_in_upstream) {
 		/* Don't say anything if head and upstream are the same. */
 		if (rev.pending.nr == 2) {
@@ -1354,6 +1365,13 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		numbered = 1;
 	if (numbered)
 		rev.total = total + start_number - 1;
+	if (cover_letter == -1) {
+		if (config_cover_letter == COVER_AUTO)
+			cover_letter = (total > 1);
+		else
+			cover_letter = (config_cover_letter == COVER_ON);
+	}
+
 	if (in_reply_to || thread || cover_letter)
 		rev.ref_message_ids = xcalloc(1, sizeof(struct string_list));
 	if (in_reply_to) {
@@ -1365,6 +1383,8 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	if (cover_letter) {
 		if (thread)
 			gen_message_id(&rev, "cover");
+		if (!branch_name)
+			branch_name = find_branch_name(&rev);
 		make_cover_letter(&rev, use_stdout,
 				  origin, nr, list, head, branch_name, quiet);
 		total++;

t/t4014-format-patch.sh

@@ -1289,4 +1289,32 @@ test_expect_success 'cover letter with nothing' '
 	test_line_count = 0 actual
 '
 
+test_expect_success 'cover letter auto' '
+	mkdir -p tmp &&
+	test_when_finished "rm -rf tmp;
+		git config --unset format.coverletter" &&
+
+	git config format.coverletter auto &&
+	git format-patch -o tmp -1 >list &&
+	test_line_count = 1 list &&
+	git format-patch -o tmp -2 >list &&
+	test_line_count = 3 list
+'
+
+test_expect_success 'cover letter auto user override' '
+	mkdir -p tmp &&
+	test_when_finished "rm -rf tmp;
+		git config --unset format.coverletter" &&
+
+	git config format.coverletter auto &&
+	git format-patch -o tmp --cover-letter -1 >list &&
+	test_line_count = 2 list &&
+	git format-patch -o tmp --cover-letter -2 >list &&
+	test_line_count = 3 list &&
+	git format-patch -o tmp --no-cover-letter -1 >list &&
+	test_line_count = 1 list &&
+	git format-patch -o tmp --no-cover-letter -2 >list &&
+	test_line_count = 2 list
+'
+
 test_done