[PATCH] Changed timestamp behavior of options -c/-C/--amend

[Erick Mattos <erick.mattos@gmail.com>]

The code herein changes commit timestamp recording from a source in a
more intuitive way.

Description:
When we use one of the options above we are normally trying to do mainly
two things: one is using the source as a template and second is to
recreate a commit with corrections.

In the first case timestamp should by default be taken by the time we
are doing the commit, not by the source.  On the second case the actual
behavior is acceptable.

Anyway this update creates new options for choosing the source timestamp
or a new one.  And set as default for -c option (editing one) to take a
new timestamp and for -C option the source timestamp.  That is because
we are normally using the source as template when we we are editing and
as a correction when we are just copying it.

Those options are also useful for --amend option which is by default
behaving the same.

Signed-off-by: Erick Mattos <erick.mattos@gmail.com>
---
 Documentation/git-commit.txt |   10 ++++++++--
 builtin-commit.c             |   15 ++++++++++++---
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index 0578a40..27c61d2 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -10,6 +10,7 @@ SYNOPSIS
 [verse]
 'git commit' [-a | --interactive] [-s] [-v] [-u<mode>] [--amend] [--dry-run]
 	   [(-c | -C) <commit>] [-F <file> | -m <msg>]
+	   [(--old-timestamp | --new-timestamp)]
 	   [--allow-empty] [--no-verify] [-e] [--author=<author>]
 	   [--cleanup=<mode>] [--] [[-i | -o ]<file>...]
 
@@ -61,13 +62,16 @@ OPTIONS
 -C <commit>::
 --reuse-message=<commit>::
 	Take an existing commit object, and reuse the log message
-	and the authorship information (including the timestamp)
-	when creating the commit.
+	and the authorship information when creating the commit.
+	By default, timestamp is taken from specified commit unless
+	option --new-timestamp is included.
 
 -c <commit>::
 --reedit-message=<commit>::
 	Like '-C', but with '-c' the editor is invoked, so that
 	the user can further edit the commit message.
+	By default, timestamp is recalculated and not taken from
+	specified commit unless option --old-timestamp is included.
 
 -F <file>::
 --file=<file>::
@@ -134,6 +138,8 @@ OPTIONS
 	current tip -- if it was a merge, it will have the parents of
 	the current tip as parents -- so the current top commit is
 	discarded.
+	By default, timestamp is taken from latest commit unless option
+	--new-timestamp is included.
 +
 --
 It is a rough equivalent for:
diff --git a/builtin-commit.c b/builtin-commit.c
index c395cbf..a924584 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -52,6 +52,7 @@ static char *edit_message, *use_message;
 static char *author_name, *author_email, *author_date;
 static int all, edit_flag, also, interactive, only, amend, signoff;
 static int quiet, verbose, no_verify, allow_empty, dry_run;
+static int old_timestamp, new_timestamp;
 static char *untracked_files_arg;
 /*
  * The default commit message cleanup mode will remove the lines
@@ -91,8 +92,10 @@ static struct option builtin_commit_options[] = {
 	OPT_FILENAME('F', "file", &logfile, "read log from file"),
 	OPT_STRING(0, "author", &force_author, "AUTHOR", "override author for commit"),
 	OPT_CALLBACK('m', "message", &message, "MESSAGE", "specify commit message", opt_parse_m),
-	OPT_STRING('c', "reedit-message", &edit_message, "COMMIT", "reuse and edit message from specified commit "),
+	OPT_STRING('c', "reedit-message", &edit_message, "COMMIT", "reuse and edit message from specified commit"),
 	OPT_STRING('C', "reuse-message", &use_message, "COMMIT", "reuse message from specified commit"),
+	OPT_BOOLEAN(0, "old-timestamp", &old_timestamp, "reuse previous commit's timestamp"),
+	OPT_BOOLEAN(0, "new-timestamp", &new_timestamp, "regenerate timestamp, ignoring previous one"),
 	OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
 	OPT_FILENAME('t', "template", &template_file, "use specified template file"),
 	OPT_BOOLEAN('e', "edit", &edit_flag, "force edit of commit"),
@@ -396,7 +399,8 @@ static void determine_author_info(void)
 
 		name = xstrndup(a + 8, lb - (a + 8));
 		email = xstrndup(lb + 2, rb - (lb + 2));
-		date = xstrndup(rb + 2, eol - (rb + 2));
+		if (!new_timestamp)
+			date = xstrndup(rb + 2, eol - (rb + 2));
 	}
 
 	if (force_author) {
@@ -763,11 +767,16 @@ static int parse_and_validate_options(int argc, const char *argv[],
 		die("You have nothing to amend.");
 	if (amend && in_merge)
 		die("You are in the middle of a merge -- cannot amend.");
+	if (old_timestamp && new_timestamp)
+		die("You can not use --old-timesamp and --new-timestamp together.");
 
 	if (use_message)
 		f++;
-	if (edit_message)
+	if (edit_message) {
+		if (!old_timestamp)
+			new_timestamp = 1;
 		f++;
+	}
 	if (logfile)
 		f++;
 	if (f > 1)
-- 
1.6.5.2.102.g3ad0