format-patch: autonumber by default

format-patch is most commonly used for multiple patches at once when
sending a patchset, in which case we want to number the patches; on
the other hand, single patches are not usually expected to be
numbered.

In other words, the typical behavior expected from format-patch is the
one obtained by enabling autonumber, so we set it to be the default.

Users that want to disable numbering for a particular patchset can do
so with the existing -N command-line switch.  Users that want to
change the default behavior can use the format.numbering config key.

Signed-off-by: Brian Gernhardt <benji@silverinsanity.com>
Test-updates-by: Jeff King <peff@peff.net>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -640,10 +640,11 @@ fetch.unpackLimit::
 	`transfer.unpackLimit` is used instead.
 
 format.numbered::
-	A boolean which can enable sequence numbers in patch subjects.
-	Setting this option to "auto" will enable it only if there is
-	more than one patch.  See --numbered option in
-	linkgit:git-format-patch[1].
+	A boolean which can enable or disable sequence numbers in patch
+	subjects.  It defaults to "auto" which enables it only if there
+	is more than one patch.  It can be enabled or disabled for all
+	messages by setting it to "true" or "false".  See --numbered
+	option in linkgit:git-format-patch[1].
 
 format.headers::
 	Additional email headers to include in a patch to be submitted

Documentation/git-format-patch.txt

@@ -58,8 +58,10 @@ output, unless the --stdout option is specified.
 If -o is specified, output files are created in <dir>.  Otherwise
 they are created in the current working directory.
 
-If -n is specified, instead of "[PATCH] Subject", the first line
-is formatted as "[PATCH n/m] Subject".
+By default, the subject of a single patch is "[PATCH] First Line" and
+the subject when multiple patches are output is "[PATCH n/m] First
+Line". To force 1/1 to be added for a single patch, use -n.  To omit
+patch numbers from the subject, use -N
 
 If given --thread, 'git-format-patch' will generate In-Reply-To and
 References headers to make the second and subsequent patch mails appear
@@ -81,7 +83,7 @@ include::diff-options.txt[]
 
 -n::
 --numbered::
-	Name output in '[PATCH n/m]' format.
+	Name output in '[PATCH n/m]' format, even with a single patch.
 
 -N::
 --no-numbered::

builtin-log.c

@@ -426,7 +426,7 @@ static int istitlechar(char c)
 
 static const char *fmt_patch_suffix = ".patch";
 static int numbered = 0;
-static int auto_number = 0;
+static int auto_number = 1;
 
 static char **extra_hdr;
 static int extra_hdr_nr;
@@ -485,6 +485,7 @@ static int git_format_config(const char *var, const char *value, void *cb)
 			return 0;
 		}
 		numbered = git_config_bool(var, value);
+		auto_number = auto_number && numbered;
 		return 0;
 	}
 

t/t4013-diff-various.sh

@@ -236,12 +236,15 @@ show --patch-with-stat --summary side
 format-patch --stdout initial..side
 format-patch --stdout initial..master^
 format-patch --stdout initial..master
+format-patch --stdout --no-numbered initial..master
+format-patch --stdout --numbered initial..master
 format-patch --attach --stdout initial..side
 format-patch --attach --stdout initial..master^
 format-patch --attach --stdout initial..master
 format-patch --inline --stdout initial..side
 format-patch --inline --stdout initial..master^
 format-patch --inline --stdout initial..master
+format-patch --inline --stdout initial..master
 format-patch --inline --stdout --subject-prefix=TESTCASE initial..master
 config format.subjectprefix DIFFERENT_PREFIX
 format-patch --inline --stdout initial..master^^

t/t4013/diff.format-patch_--attach_--stdout_initial..master

@@ -2,7 +2,7 @@ $ git format-patch --attach --stdout initial..master
 From 1bde4ae5f36c8d9abe3a0fce0c6aab3c4a12fe44 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:01:00 +0000
-Subject: [PATCH] Second
+Subject: [PATCH 1/3] Second
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 
@@ -63,7 +63,7 @@ index 01e79c3..0000000
 From 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:02:00 +0000
-Subject: [PATCH] Third
+Subject: [PATCH 2/3] Third
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 
@@ -111,7 +111,7 @@ index 0000000..b1e6722
 From c7a2ab9e8eac7b117442a607d5a9b3950ae34d5a Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:03:00 +0000
-Subject: [PATCH] Side
+Subject: [PATCH 3/3] Side
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 

t/t4013/diff.format-patch_--attach_--stdout_initial..master^

@@ -2,7 +2,7 @@ $ git format-patch --attach --stdout initial..master^
 From 1bde4ae5f36c8d9abe3a0fce0c6aab3c4a12fe44 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:01:00 +0000
-Subject: [PATCH] Second
+Subject: [PATCH 1/2] Second
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 
@@ -63,7 +63,7 @@ index 01e79c3..0000000
 From 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:02:00 +0000
-Subject: [PATCH] Third
+Subject: [PATCH 2/2] Third
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 

t/t4013/diff.format-patch_--inline_--stdout_--subject-prefix=TESTCASE_initial..master

@@ -2,7 +2,7 @@ $ git format-patch --inline --stdout --subject-prefix=TESTCASE initial..master
 From 1bde4ae5f36c8d9abe3a0fce0c6aab3c4a12fe44 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:01:00 +0000
-Subject: [TESTCASE] Second
+Subject: [TESTCASE 1/3] Second
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 
@@ -63,7 +63,7 @@ index 01e79c3..0000000
 From 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:02:00 +0000
-Subject: [TESTCASE] Third
+Subject: [TESTCASE 2/3] Third
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 
@@ -111,7 +111,7 @@ index 0000000..b1e6722
 From c7a2ab9e8eac7b117442a607d5a9b3950ae34d5a Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:03:00 +0000
-Subject: [TESTCASE] Side
+Subject: [TESTCASE 3/3] Side
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 

t/t4013/diff.format-patch_--inline_--stdout_initial..master

@@ -2,7 +2,7 @@ $ git format-patch --inline --stdout initial..master
 From 1bde4ae5f36c8d9abe3a0fce0c6aab3c4a12fe44 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:01:00 +0000
-Subject: [PATCH] Second
+Subject: [PATCH 1/3] Second
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 
@@ -63,7 +63,7 @@ index 01e79c3..0000000
 From 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:02:00 +0000
-Subject: [PATCH] Third
+Subject: [PATCH 2/3] Third
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 
@@ -111,7 +111,7 @@ index 0000000..b1e6722
 From c7a2ab9e8eac7b117442a607d5a9b3950ae34d5a Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:03:00 +0000
-Subject: [PATCH] Side
+Subject: [PATCH 3/3] Side
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 

t/t4013/diff.format-patch_--inline_--stdout_initial..master^

@@ -2,7 +2,7 @@ $ git format-patch --inline --stdout initial..master^
 From 1bde4ae5f36c8d9abe3a0fce0c6aab3c4a12fe44 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:01:00 +0000
-Subject: [PATCH] Second
+Subject: [PATCH 1/2] Second
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 
@@ -63,7 +63,7 @@ index 01e79c3..0000000
 From 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0 Mon Sep 17 00:00:00 2001
 From: A U Thor <author@example.com>
 Date: Mon, 26 Jun 2006 00:02:00 +0000
-Subject: [PATCH] Third
+Subject: [PATCH 2/2] Third
 MIME-Version: 1.0
 Content-Type: multipart/mixed; boundary="------------g-i-t--v-e-r-s-i-o-n"
 

t/t4013/diff.format-patch_--stdout_--no-numbered_initial..master

@@ -0,0 +1,127 @@
+$ git format-patch --stdout --no-numbered initial..master
+From 1bde4ae5f36c8d9abe3a0fce0c6aab3c4a12fe44 Mon Sep 17 00:00:00 2001
+From: A U Thor <author@example.com>
+Date: Mon, 26 Jun 2006 00:01:00 +0000
+Subject: [PATCH] Second
+
+This is the second commit.
+---
+ dir/sub |    2 ++
+ file0   |    3 +++
+ file2   |    3 ---
+ 3 files changed, 5 insertions(+), 3 deletions(-)
+ delete mode 100644 file2
+
+diff --git a/dir/sub b/dir/sub
+index 35d242b..8422d40 100644
+--- a/dir/sub
++++ b/dir/sub
+@@ -1,2 +1,4 @@
+ A
+ B
++C
++D
+diff --git a/file0 b/file0
+index 01e79c3..b414108 100644
+--- a/file0
++++ b/file0
+@@ -1,3 +1,6 @@
+ 1
+ 2
+ 3
++4
++5
++6
+diff --git a/file2 b/file2
+deleted file mode 100644
+index 01e79c3..0000000
+--- a/file2
++++ /dev/null
+@@ -1,3 +0,0 @@
+-1
+-2
+-3
+-- 
+g-i-t--v-e-r-s-i-o-n
+
+
+From 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0 Mon Sep 17 00:00:00 2001
+From: A U Thor <author@example.com>
+Date: Mon, 26 Jun 2006 00:02:00 +0000
+Subject: [PATCH] Third
+
+---
+ dir/sub |    2 ++
+ file1   |    3 +++
+ 2 files changed, 5 insertions(+), 0 deletions(-)
+ create mode 100644 file1
+
+diff --git a/dir/sub b/dir/sub
+index 8422d40..cead32e 100644
+--- a/dir/sub
++++ b/dir/sub
+@@ -2,3 +2,5 @@ A
+ B
+ C
+ D
++E
++F
+diff --git a/file1 b/file1
+new file mode 100644
+index 0000000..b1e6722
+--- /dev/null
++++ b/file1
+@@ -0,0 +1,3 @@
++A
++B
++C
+-- 
+g-i-t--v-e-r-s-i-o-n
+
+
+From c7a2ab9e8eac7b117442a607d5a9b3950ae34d5a Mon Sep 17 00:00:00 2001
+From: A U Thor <author@example.com>
+Date: Mon, 26 Jun 2006 00:03:00 +0000
+Subject: [PATCH] Side
+
+---
+ dir/sub |    2 ++
+ file0   |    3 +++
+ file3   |    4 ++++
+ 3 files changed, 9 insertions(+), 0 deletions(-)
+ create mode 100644 file3
+
+diff --git a/dir/sub b/dir/sub
+index 35d242b..7289e35 100644
+--- a/dir/sub
++++ b/dir/sub
+@@ -1,2 +1,4 @@
+ A
+ B
++1
++2
+diff --git a/file0 b/file0
+index 01e79c3..f4615da 100644
+--- a/file0
++++ b/file0
+@@ -1,3 +1,6 @@
+ 1
+ 2
+ 3
++A
++B
++C
+diff --git a/file3 b/file3
+new file mode 100644
+index 0000000..7289e35
+--- /dev/null
++++ b/file3
+@@ -0,0 +1,4 @@
++A
++B
++1
++2
+-- 
+g-i-t--v-e-r-s-i-o-n
+
+$