[PATCH v4 0/4] CHERRY_PICK_HEAD

[PATCH v4 0/4] CHERRY_PICK_HEAD

[Jay Soffian]

As compared to v3:

- Adds pristine-detach to the start of the series. I thought it made sense to
  refactor before adding the additional tests instead of after.

- Fixes t3404#16. This was due to CHERRY_PICK_HEAD overriding the authorship set
  by git rebase --interactive when used with --no-commit. Now we just don't
  write CHERRY_PICK_HEAD when --no-commit is given. This also addresses Junio's
  concern that doing so would be a regression.

  (That said, I wonder if rebase --interactive should use --reset-author when
  committing after using cherry-pick --no-commit just in case.)

- Addresses (I think) the various other feedback given in
  http://thread.gmane.org/gmane.comp.version-control.git/167031

Jay Soffian (3):
  Introduce CHERRY_PICK_HEAD
  bash: teach __git_ps1 about CHERRY_PICK_HEAD
  Teach commit about CHERRY_PICK_HEAD

Jonathan Nieder (1):
  t3507: introduce pristine-detach helper

 Documentation/git-cherry-pick.txt      |   19 ++++
 Documentation/git-commit.txt           |    7 +-
 Documentation/revisions.txt            |    5 +-
 branch.c                               |    1 +
 builtin/commit.c                       |  156 +++++++++++++++++++++++---------
 builtin/merge.c                        |    7 ++
 builtin/revert.c                       |   75 +++++-----------
 contrib/completion/git-completion.bash |    2 +
 t/t3507-cherry-pick-conflict.sh        |  150 ++++++++++++++++++++-----------
 t/t7509-commit.sh                      |   29 ++++++
 wt-status.c                            |    4 +-
 wt-status.h                            |    9 ++-
 12 files changed, 308 insertions(+), 156 deletions(-)

-- 
1.7.4.1.51.g615e0

[PATCH v4 1/4] t3507: introduce pristine-detach helper

[Jay Soffian]

From: Jonathan Nieder <jrnieder@gmail.com>

All the tests in t3507 (cherry-pick with conflicts) begin with the
same checkout + read-tree + clean incantation to ensure a predictable
starting point.  Factor out a function for that so the interesting
part of the tests is easier to read.

The "update-index --refresh" and "diff-index --exit-code HEAD" are not
necessary as the point of this testsuite is not about testing
"read-tree --reset".

Improved-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 t/t3507-cherry-pick-conflict.sh |   76 +++++++++++---------------------------
 1 files changed, 22 insertions(+), 54 deletions(-)

diff --git a/t/t3507-cherry-pick-conflict.sh b/t/t3507-cherry-pick-conflict.sh
index 607bf25..2313d79 100755
--- a/t/t3507-cherry-pick-conflict.sh
+++ b/t/t3507-cherry-pick-conflict.sh
@@ -11,6 +11,18 @@ test_description='test cherry-pick and revert with conflicts
 
 . ./test-lib.sh
 
+test_cmp_rev () {
+	git rev-parse --verify "$1" >expect.rev &&
+	git rev-parse --verify "$2" >actual.rev &&
+	test_cmp expect.rev actual.rev
+}
+
+pristine_detach () {
+	git checkout -f "$1^0" &&
+	git read-tree -u --reset HEAD &&
+	git clean -d -f -f -q -x
+}
+
 test_expect_success setup '
 
 	echo unrelated >unrelated &&
@@ -23,13 +35,7 @@ test_expect_success setup '
 '
 
 test_expect_success 'failed cherry-pick does not advance HEAD' '
-
-	git checkout -f initial^0 &&
-	git read-tree -u --reset HEAD &&
-	git clean -d -f -f -q -x &&
-
-	git update-index --refresh &&
-	git diff-index --exit-code HEAD &&
+	pristine_detach initial &&
 
 	head=$(git rev-parse HEAD) &&
 	test_must_fail git cherry-pick picked &&
@@ -39,12 +45,7 @@ test_expect_success 'failed cherry-pick does not advance HEAD' '
 '
 
 test_expect_success 'advice from failed cherry-pick' "
-	git checkout -f initial^0 &&
-	git read-tree -u --reset HEAD &&
-	git clean -d -f -f -q -x &&
-
-	git update-index --refresh &&
-	git diff-index --exit-code HEAD &&
+	pristine_detach initial &&
 
 	picked=\$(git rev-parse --short picked) &&
 	cat <<-EOF >expected &&
@@ -59,13 +60,7 @@ test_expect_success 'advice from failed cherry-pick' "
 "
 
 test_expect_success 'failed cherry-pick produces dirty index' '
-
-	git checkout -f initial^0 &&
-	git read-tree -u --reset HEAD &&
-	git clean -d -f -f -q -x &&
-
-	git update-index --refresh &&
-	git diff-index --exit-code HEAD &&
+	pristine_detach initial &&
 
 	test_must_fail git cherry-pick picked &&
 
@@ -74,9 +69,7 @@ test_expect_success 'failed cherry-pick produces dirty index' '
 '
 
 test_expect_success 'failed cherry-pick registers participants in index' '
-
-	git read-tree -u --reset HEAD &&
-	git clean -d -f -f -q -x &&
+	pristine_detach initial &&
 	{
 		git checkout base -- foo &&
 		git ls-files --stage foo &&
@@ -90,10 +83,7 @@ test_expect_success 'failed cherry-pick registers participants in index' '
 		2 s/ 0	/ 2	/
 		3 s/ 0	/ 3	/
 	" < stages > expected &&
-	git checkout -f initial^0 &&
-
-	git update-index --refresh &&
-	git diff-index --exit-code HEAD &&
+	git read-tree -u --reset HEAD &&
 
 	test_must_fail git cherry-pick picked &&
 	git ls-files --stage --unmerged > actual &&
@@ -102,10 +92,7 @@ test_expect_success 'failed cherry-pick registers participants in index' '
 '
 
 test_expect_success 'failed cherry-pick describes conflict in work tree' '
-
-	git checkout -f initial^0 &&
-	git read-tree -u --reset HEAD &&
-	git clean -d -f -f -q -x &&
+	pristine_detach initial &&
 	cat <<-EOF > expected &&
 	<<<<<<< HEAD
 	a
@@ -114,9 +101,6 @@ test_expect_success 'failed cherry-pick describes conflict in work tree' '
 	>>>>>>> objid picked
 	EOF
 
-	git update-index --refresh &&
-	git diff-index --exit-code HEAD &&
-
 	test_must_fail git cherry-pick picked &&
 
 	sed "s/[a-f0-9]*\.\.\./objid/" foo > actual &&
@@ -124,11 +108,8 @@ test_expect_success 'failed cherry-pick describes conflict in work tree' '
 '
 
 test_expect_success 'diff3 -m style' '
-
+	pristine_detach initial &&
 	git config merge.conflictstyle diff3 &&
-	git checkout -f initial^0 &&
-	git read-tree -u --reset HEAD &&
-	git clean -d -f -f -q -x &&
 	cat <<-EOF > expected &&
 	<<<<<<< HEAD
 	a
@@ -139,9 +120,6 @@ test_expect_success 'diff3 -m style' '
 	>>>>>>> objid picked
 	EOF
 
-	git update-index --refresh &&
-	git diff-index --exit-code HEAD &&
-
 	test_must_fail git cherry-pick picked &&
 
 	sed "s/[a-f0-9]*\.\.\./objid/" foo > actual &&
@@ -149,10 +127,8 @@ test_expect_success 'diff3 -m style' '
 '
 
 test_expect_success 'revert also handles conflicts sanely' '
-
 	git config --unset merge.conflictstyle &&
-	git read-tree -u --reset HEAD &&
-	git clean -d -f -f -q -x &&
+	pristine_detach initial &&
 	cat <<-EOF > expected &&
 	<<<<<<< HEAD
 	a
@@ -173,10 +149,7 @@ test_expect_success 'revert also handles conflicts sanely' '
 		2 s/ 0	/ 2	/
 		3 s/ 0	/ 3	/
 	" < stages > expected-stages &&
-	git checkout -f initial^0 &&
-
-	git update-index --refresh &&
-	git diff-index --exit-code HEAD &&
+	git read-tree -u --reset HEAD &&
 
 	head=$(git rev-parse HEAD) &&
 	test_must_fail git revert picked &&
@@ -192,10 +165,8 @@ test_expect_success 'revert also handles conflicts sanely' '
 '
 
 test_expect_success 'revert conflict, diff3 -m style' '
+	pristine_detach initial &&
 	git config merge.conflictstyle diff3 &&
-	git checkout -f initial^0 &&
-	git read-tree -u --reset HEAD &&
-	git clean -d -f -f -q -x &&
 	cat <<-EOF > expected &&
 	<<<<<<< HEAD
 	a
@@ -206,9 +177,6 @@ test_expect_success 'revert conflict, diff3 -m style' '
 	>>>>>>> parent of objid picked
 	EOF
 
-	git update-index --refresh &&
-	git diff-index --exit-code HEAD &&
-
 	test_must_fail git revert picked &&
 
 	sed "s/[a-f0-9]*\.\.\./objid/" foo > actual &&
-- 
1.7.4.1.51.g615e0

[PATCH v4 2/4] Introduce CHERRY_PICK_HEAD

[Jay Soffian]

When a cherry-pick conflicts git advises:

 $ git commit -c <original commit id>

to preserve the original commit message and authorship. Instead, let's
record the original commit id in CHERRY_PICK_HEAD and advise:

  $ git commit -c CHERRY_PICK_HEAD

A later patch teaches git to handle the '-c CHERRY_PICK_HEAD' part.
Note that we record CHERRY_PICK_HEAD even in the case where there
are no conflicts so that we may use it to communicate authorship to
commit; this will then allow us to remove set_author_ident_env from
revert.c. However, we do not record CHERRY_PICK_HEAD when --no-commit
is used, as presumably the user intends to further edit the commit
and possibly even cherry-pick additional commits on top.

Tests and documentation contributed by Jonathan Nieder.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
---
 Documentation/git-cherry-pick.txt |   19 +++++++++
 Documentation/revisions.txt       |    5 ++-
 branch.c                          |    1 +
 builtin/commit.c                  |    1 +
 builtin/merge.c                   |    7 +++
 builtin/revert.c                  |   27 ++++++++++++-
 t/t3507-cherry-pick-conflict.sh   |   76 ++++++++++++++++++++++++++++++++++++-
 7 files changed, 132 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-cherry-pick.txt b/Documentation/git-cherry-pick.txt
index 749d68a..5d85daa 100644
--- a/Documentation/git-cherry-pick.txt
+++ b/Documentation/git-cherry-pick.txt
@@ -16,6 +16,25 @@ Given one or more existing commits, apply the change each one
 introduces, recording a new commit for each.  This requires your
 working tree to be clean (no modifications from the HEAD commit).
 
+When it is not obvious how to apply a change, the following
+happens:
+
+1. The current branch and `HEAD` pointer stay at the last commit
+   successfully made.
+2. The `CHERRY_PICK_HEAD` ref is set to point at the commit that
+   introduced the change that is difficult to apply.
+3. Paths in which the change applied cleanly are updated both
+   in the index file and in your working tree.
+4. For conflicting paths, the index file records up to three
+   versions, as described in the "TRUE MERGE" section of
+   linkgit:git-merge[1].  The working tree files will include
+   a description of the conflict bracketed by the usual
+   conflict markers `<<<<<<<` and `>>>>>>>`.
+5. No other modifications are made.
+
+See linkgit:git-merge[1] for some hints on resolving such
+conflicts.
+
 OPTIONS
 -------
 <commit>...::
diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index 9e92734..04fceee 100644
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -25,7 +25,8 @@ blobs contained in a commit.
   first match in the following rules:
 
   . if `$GIT_DIR/<name>` exists, that is what you mean (this is usually
-    useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD` and `MERGE_HEAD`);
+    useful only for `HEAD`, `FETCH_HEAD`, `ORIG_HEAD`, `MERGE_HEAD`
+    and `CHERRY_PICK_HEAD`);
 
   . otherwise, `refs/<name>` if exists;
 
@@ -46,6 +47,8 @@ you can change the tip of the branch back to the state before you ran
 them easily.
 MERGE_HEAD records the commit(s) you are merging into your branch
 when you run 'git merge'.
+CHERRY_PICK_HEAD records the commit you are cherry-picking
+when you run 'git cherry-pick'.
 +
 Note that any of the `refs/*` cases above may come either from
 the `$GIT_DIR/refs` directory or from the `$GIT_DIR/packed-refs` file.
diff --git a/branch.c b/branch.c
index 93dc866..dc23e95 100644
--- a/branch.c
+++ b/branch.c
@@ -217,6 +217,7 @@ void create_branch(const char *head,
 
 void remove_branch_state(void)
 {
+	unlink(git_path("CHERRY_PICK_HEAD"));
 	unlink(git_path("MERGE_HEAD"));
 	unlink(git_path("MERGE_RR"));
 	unlink(git_path("MERGE_MSG"));
diff --git a/builtin/commit.c b/builtin/commit.c
index d7f55e3..7acd559 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1424,6 +1424,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		die("cannot update HEAD ref");
 	}
 
+	unlink(git_path("CHERRY_PICK_HEAD"));
 	unlink(git_path("MERGE_HEAD"));
 	unlink(git_path("MERGE_MSG"));
 	unlink(git_path("MERGE_MODE"));
diff --git a/builtin/merge.c b/builtin/merge.c
index 8c58c3c..1b94c94 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -971,6 +971,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		else
 			die("You have not concluded your merge (MERGE_HEAD exists).");
 	}
+	if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
+		if (advice_resolve_conflict)
+			die("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
+			    "Please, commit your changes before you can merge.");
+		else
+			die("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).");
+	}
 	resolve_undo_clear();
 
 	if (verbosity < 0)
diff --git a/builtin/revert.c b/builtin/revert.c
index dc1b702..deecaab 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -248,6 +248,22 @@ static void set_author_ident_env(const char *message)
 			sha1_to_hex(commit->object.sha1));
 }
 
+static void write_cherry_pick_head(void)
+{
+	int fd;
+	struct strbuf buf = STRBUF_INIT;
+
+	strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
+
+	fd = open(git_path("CHERRY_PICK_HEAD"), O_WRONLY | O_CREAT, 0666);
+	if (fd < 0)
+		die_errno("Could not open '%s' for writing",
+			  git_path("CHERRY_PICK_HEAD"));
+	if (write_in_full(fd, buf.buf, buf.len) != buf.len || close(fd))
+		die_errno("Could not write to '%s'", git_path("CHERRY_PICK_HEAD"));
+	strbuf_release(&buf);
+}
+
 static void advise(const char *advice, ...)
 {
 	va_list params;
@@ -263,6 +279,12 @@ static void print_advice(void)
 
 	if (msg) {
 		fprintf(stderr, "%s\n", msg);
+		/*
+		 * A conflict has occured but the porcelain
+		 * (typically rebase --interactive) wants to take care
+		 * of the commit itself so remove CHERRY_PICK_HEAD
+		 */
+		unlink(git_path("CHERRY_PICK_HEAD"));
 		return;
 	}
 
@@ -270,8 +292,7 @@ static void print_advice(void)
 	advise("with 'git add <paths>' or 'git rm <paths>'");
 
 	if (action == CHERRY_PICK)
-		advise("and commit the result with 'git commit -c %s'",
-		       find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
+		advise("and commit the result with 'git commit -c CHERRY_PICK_HEAD'");
 }
 
 static void write_message(struct strbuf *msgbuf, const char *filename)
@@ -504,6 +525,8 @@ static int do_pick_commit(void)
 			strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 			strbuf_addstr(&msgbuf, ")\n");
 		}
+		if (!no_commit)
+			write_cherry_pick_head();
 	}
 
 	if (!strategy || !strcmp(strategy, "recursive") || action == REVERT) {
diff --git a/t/t3507-cherry-pick-conflict.sh b/t/t3507-cherry-pick-conflict.sh
index 2313d79..e0bf356 100755
--- a/t/t3507-cherry-pick-conflict.sh
+++ b/t/t3507-cherry-pick-conflict.sh
@@ -52,13 +52,87 @@ test_expect_success 'advice from failed cherry-pick' "
 	error: could not apply \$picked... picked
 	hint: after resolving the conflicts, mark the corrected paths
 	hint: with 'git add <paths>' or 'git rm <paths>'
-	hint: and commit the result with 'git commit -c \$picked'
+	hint: and commit the result with 'git commit -c CHERRY_PICK_HEAD'
 	EOF
 	test_must_fail git cherry-pick picked 2>actual &&
 
 	test_cmp expected actual
 "
 
+test_expect_success 'failed cherry-pick sets CHERRY_PICK_HEAD' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick picked &&
+	test_cmp_rev picked CHERRY_PICK_HEAD
+'
+
+test_expect_success 'successful cherry-pick does not set CHERRY_PICK_HEAD' '
+	pristine_detach initial &&
+	git cherry-pick base &&
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
+test_expect_success 'cherry-pick --no-commit does not set CHERRY_PICK_HEAD' '
+	pristine_detach initial &&
+	git cherry-pick --no-commit base &&
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
+test_expect_success 'GIT_CHERRY_PICK_HELP suppresses CHERRY_PICK_HEAD' '
+	pristine_detach initial &&
+	(
+		GIT_CHERRY_PICK_HELP="and then do something else" &&
+		export GIT_CHERRY_PICK_HELP &&
+		test_must_fail git cherry-pick picked
+	) &&
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
+test_expect_success 'git reset clears CHERRY_PICK_HEAD' '
+	pristine_detach initial &&
+
+	test_must_fail git cherry-pick picked &&
+	git reset &&
+
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
+test_expect_success 'failed commit does not clear CHERRY_PICK_HEAD' '
+	pristine_detach initial &&
+
+	test_must_fail git cherry-pick picked &&
+	test_must_fail git commit &&
+
+	test_cmp_rev picked CHERRY_PICK_HEAD
+'
+
+test_expect_success 'cancelled commit does not clear CHERRY_PICK_HEAD' '
+	pristine_detach initial &&
+
+	test_must_fail git cherry-pick picked &&
+	echo resolved >foo &&
+	git add foo &&
+	git update-index --refresh -q &&
+	test_must_fail git diff-index --exit-code HEAD &&
+	(
+		GIT_EDITOR=false &&
+		export GIT_EDITOR &&
+		test_must_fail git commit
+	) &&
+
+	test_cmp_rev picked CHERRY_PICK_HEAD
+'
+
+test_expect_success 'successful commit clears CHERRY_PICK_HEAD' '
+	pristine_detach initial &&
+
+	test_must_fail git cherry-pick picked &&
+	echo resolved >foo &&
+	git add foo &&
+	git commit &&
+
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD
+'
+
 test_expect_success 'failed cherry-pick produces dirty index' '
 	pristine_detach initial &&
 
-- 
1.7.4.1.51.g615e0

[PATCH v4 3/4] bash: teach __git_ps1 about CHERRY_PICK_HEAD

[Jay Soffian]

Make the git prompt (when enabled) show a CHERRY-PICKING indicator
when we are in the middle of a conflicted cherry-pick, analogous
to the existing MERGING and BISECTING flags.

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 contrib/completion/git-completion.bash |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 893b771..0b0b913 100755
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -246,6 +246,8 @@ __git_ps1 ()
 				fi
 			elif [ -f "$g/MERGE_HEAD" ]; then
 				r="|MERGING"
+			elif [ -f "$g/CHERRY_PICK_HEAD" ]; then
+				r="|CHERRY-PICKING"
 			elif [ -f "$g/BISECT_LOG" ]; then
 				r="|BISECTING"
 			fi
-- 
1.7.4.1.51.g615e0

[PATCH v4 4/4] Teach commit about CHERRY_PICK_HEAD

[Jay Soffian]

Previously the user was advised to use commit -c CHERRY_PICK_HEAD after
a conflicting cherry-pick. While this would preserve the original
commit's authorship, it would sadly discard cherry-pick's carefully
crafted MERGE_MSG (which contains the list of conflicts as well as the
original commit-id in the case of cherry-pick -x).

On the other hand, if a bare 'commit' were performed, it would preserve
the MERGE_MSG while resetting the authorship.

In other words, there was no way to simultaneously take the authorship
from CHERRY_PICK_HEAD and the commit message from MERGE_MSG.

This change fixes that situation. A bare 'commit' will now take the
authorship from CHERRY_PICK_HEAD and the commit message from MERGE_MSG.
If the user wishes to reset authorship, that must now be done explicitly
via --reset-author.

A side-benefit of passing commit authorship along this way is that we
can eliminate redundant authorship parsing code from revert.c.

(Also removed an unused include from revert.c)

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
---
 Documentation/git-commit.txt    |    7 +-
 builtin/commit.c                |  155 ++++++++++++++++++++++++++++-----------
 builtin/revert.c                |   56 +--------------
 t/t3507-cherry-pick-conflict.sh |    2 +-
 t/t7509-commit.sh               |   29 +++++++
 wt-status.c                     |    4 +-
 wt-status.h                     |    9 ++-
 7 files changed, 158 insertions(+), 104 deletions(-)

diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index b586c0f..fd6a1f7 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -84,9 +84,10 @@ OPTIONS
 	linkgit:git-rebase[1] for details.
 
 --reset-author::
-	When used with -C/-c/--amend options, declare that the
-	authorship of the resulting commit now belongs of the committer.
-	This also renews the author timestamp.
+	When used with -C/-c/--amend options, or when committing after a
+	a conflicting cherry-pick, declare that the authorship of the
+	resulting commit now belongs of the committer. This also renews
+	the author timestamp.
 
 --short::
 	When doing a dry-run, give the output in the short-format. See
diff --git a/builtin/commit.c b/builtin/commit.c
index 7acd559..85e88b7 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -54,9 +54,17 @@ static const char empty_amend_advice[] =
 "it empty. You can repeat your command with --allow-empty, or you can\n"
 "remove the commit entirely with \"git reset HEAD^\".\n";
 
+static const char empty_cherry_pick_advice[] =
+"The previous cherry-pick is now empty, possibly due to conflict resolution.\n"
+"If you wish to commit it anyway, use:\n"
+"\n"
+"    git commit --allow-empty\n"
+"\n"
+"Otherwise, please use 'git reset'\n";
+
 static unsigned char head_sha1[20];
 
-static char *use_message_buffer;
+static const char *use_message_buffer;
 static const char commit_editmsg[] = "COMMIT_EDITMSG";
 static struct lock_file index_lock; /* real index */
 static struct lock_file false_lock; /* used only for partial commits */
@@ -68,6 +76,11 @@ static enum {
 
 static const char *logfile, *force_author;
 static const char *template_file;
+/*
+ * The _message variables are commit names from which to take
+ * the commit message and/or authorship.
+ */
+static const char *author_message, *author_message_buffer;
 static char *edit_message, *use_message;
 static char *fixup_message, *squash_message;
 static int all, edit_flag, also, interactive, only, amend, signoff;
@@ -88,7 +101,8 @@ static enum {
 } cleanup_mode;
 static char *cleanup_arg;
 
-static int use_editor = 1, initial_commit, in_merge, include_status = 1;
+static enum commit_whence whence;
+static int use_editor = 1, initial_commit, include_status = 1;
 static int show_ignored_in_status;
 static const char *only_include_assumed;
 static struct strbuf message;
@@ -163,6 +177,36 @@ static struct option builtin_commit_options[] = {
 	OPT_END()
 };
 
+static void determine_whence(struct wt_status *s)
+{
+	if (file_exists(git_path("MERGE_HEAD")))
+		whence = FROM_MERGE;
+	else if (file_exists(git_path("CHERRY_PICK_HEAD")))
+		whence = FROM_CHERRY_PICK;
+	else
+		whence = FROM_COMMIT;
+	if (s)
+		s->whence = whence;
+}
+
+static const char *whence_s(void)
+{
+	char *s = "";
+
+	switch (whence) {
+	case FROM_COMMIT:
+		break;
+	case FROM_MERGE:
+		s = "merge";
+		break;
+	case FROM_CHERRY_PICK:
+		s = "cherry-pick";
+		break;
+	}
+
+	return s;
+}
+
 static void rollback_index_files(void)
 {
 	switch (commit_style) {
@@ -378,8 +422,8 @@ static char *prepare_index(int argc, const char **argv, const char *prefix, int
 	 */
 	commit_style = COMMIT_PARTIAL;
 
-	if (in_merge)
-		die("cannot do a partial commit during a merge.");
+	if (whence != FROM_COMMIT)
+		die("cannot do a partial commit during a %s.", whence_s());
 
 	memset(&partial, 0, sizeof(partial));
 	partial.strdup_strings = 1;
@@ -469,18 +513,18 @@ static void determine_author_info(struct strbuf *author_ident)
 	email = getenv("GIT_AUTHOR_EMAIL");
 	date = getenv("GIT_AUTHOR_DATE");
 
-	if (use_message && !renew_authorship) {
+	if (author_message) {
 		const char *a, *lb, *rb, *eol;
 
-		a = strstr(use_message_buffer, "\nauthor ");
+		a = strstr(author_message_buffer, "\nauthor ");
 		if (!a)
-			die("invalid commit: %s", use_message);
+			die("invalid commit: %s", author_message);
 
 		lb = strchrnul(a + strlen("\nauthor "), '<');
 		rb = strchrnul(lb, '>');
 		eol = strchrnul(rb, '\n');
 		if (!*lb || !*rb || !*eol)
-			die("invalid commit: %s", use_message);
+			die("invalid commit: %s", author_message);
 
 		if (lb == a + strlen("\nauthor "))
 			/* \nauthor <foo@example.com> */
@@ -641,11 +685,15 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 	}
 
 	/*
-	 * This final case does not modify the template message,
-	 * it just sets the argument to the prepare-commit-msg hook.
+	 * The remaining cases don't modify the template message, but
+	 * just set the argument(s) to the prepare-commit-msg hook.
 	 */
-	else if (in_merge)
+	else if (whence == FROM_MERGE)
 		hook_arg1 = "merge";
+	else if (whence == FROM_CHERRY_PICK) {
+		hook_arg1 = "commit";
+		hook_arg2 = "CHERRY_PICK_HEAD";
+	}
 
 	if (squash_message) {
 		/*
@@ -694,16 +742,18 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 	strbuf_addstr(&committer_ident, git_committer_info(0));
 	if (use_editor && include_status) {
 		char *ai_tmp, *ci_tmp;
-		if (in_merge)
+		if (whence != FROM_COMMIT)
 			fprintf(fp,
 				"#\n"
-				"# It looks like you may be committing a MERGE.\n"
+				"# It looks like you may be committing a %s.\n"
 				"# If this is not correct, please remove the file\n"
 				"#	%s\n"
 				"# and try again.\n"
 				"#\n",
-				git_path("MERGE_HEAD"));
-
+				whence_s(),
+				git_path(whence == FROM_MERGE
+					 ? "MERGE_HEAD"
+					 : "CHERRY_PICK_HEAD"));
 		fprintf(fp,
 			"\n"
 			"# Please enter the commit message for your changes.");
@@ -766,11 +816,18 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 
 	fclose(fp);
 
-	if (!commitable && !in_merge && !allow_empty &&
+	/*
+	 * Reject an attempt to record a non-merge empty commit without
+	 * explicit --allow-empty. In the cherry-pick case, it may be
+	 * empty due to conflict resolution, which the user should okay.
+	 */
+	if (!commitable && whence != FROM_MERGE && !allow_empty &&
 	    !(amend && is_a_merge(head_sha1))) {
 		run_status(stdout, index_file, prefix, 0, s);
 		if (amend)
 			fputs(empty_amend_advice, stderr);
+		else if (whence == FROM_CHERRY_PICK)
+			fputs(empty_cherry_pick_advice, stderr);
 		return 0;
 	}
 
@@ -898,6 +955,28 @@ static void handle_untracked_files_arg(struct wt_status *s)
 		die("Invalid untracked files mode '%s'", untracked_files_arg);
 }
 
+static const char *read_commit_message(const char *name)
+{
+	const char *out_enc, *out;
+	struct commit *commit;
+
+	commit = lookup_commit_reference_by_name(name);
+	if (!commit)
+		die("could not lookup commit %s", name);
+	out_enc = get_commit_output_encoding();
+	out = logmsg_reencode(commit, out_enc);
+
+	/*
+	 * If we failed to reencode the buffer, just copy it
+	 * byte for byte so the user can try to fix it up.
+	 * This also handles the case where input and output
+	 * encodings are identical.
+	 */
+	if (out == NULL)
+		out = xstrdup(commit->buffer);
+	return out;
+}
+
 static int parse_and_validate_options(int argc, const char *argv[],
 				      const char * const usage[],
 				      const char *prefix,
@@ -927,8 +1006,8 @@ static int parse_and_validate_options(int argc, const char *argv[],
 	/* Sanity check options */
 	if (amend && initial_commit)
 		die("You have nothing to amend.");
-	if (amend && in_merge)
-		die("You are in the middle of a merge -- cannot amend.");
+	if (amend && whence != FROM_COMMIT)
+		die("You are in the middle of a %s -- cannot amend.", whence_s());
 	if (fixup_message && squash_message)
 		die("Options --squash and --fixup cannot be used together");
 	if (use_message)
@@ -947,26 +1026,18 @@ static int parse_and_validate_options(int argc, const char *argv[],
 		use_message = edit_message;
 	if (amend && !use_message && !fixup_message)
 		use_message = "HEAD";
-	if (!use_message && renew_authorship)
+	if (!use_message && whence != FROM_CHERRY_PICK && renew_authorship)
 		die("--reset-author can be used only with -C, -c or --amend.");
 	if (use_message) {
-		const char *out_enc;
-		struct commit *commit;
-
-		commit = lookup_commit_reference_by_name(use_message);
-		if (!commit)
-			die("could not lookup commit %s", use_message);
-		out_enc = get_commit_output_encoding();
-		use_message_buffer = logmsg_reencode(commit, out_enc);
-
-		/*
-		 * If we failed to reencode the buffer, just copy it
-		 * byte for byte so the user can try to fix it up.
-		 * This also handles the case where input and output
-		 * encodings are identical.
-		 */
-		if (use_message_buffer == NULL)
-			use_message_buffer = xstrdup(commit->buffer);
+		use_message_buffer = read_commit_message(use_message);
+		if (!renew_authorship) {
+			author_message = use_message;
+			author_message_buffer = use_message_buffer;
+		}
+	}
+	if (whence == FROM_CHERRY_PICK && !renew_authorship) {
+		author_message = "CHERRY_PICK_HEAD";
+		author_message_buffer = read_commit_message(author_message);
 	}
 
 	if (!!also + !!only + !!all + !!interactive > 1)
@@ -1117,7 +1188,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 	wt_status_prepare(&s);
 	gitmodules_config();
 	git_config(git_status_config, &s);
-	in_merge = file_exists(git_path("MERGE_HEAD"));
+	determine_whence(&s);
 	argc = parse_options(argc, argv, prefix,
 			     builtin_status_options,
 			     builtin_status_usage, 0);
@@ -1140,7 +1211,6 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 	}
 
 	s.is_initial = get_sha1(s.reference, sha1) ? 1 : 0;
-	s.in_merge = in_merge;
 	s.ignore_submodule_arg = ignore_submodule_arg;
 	wt_status_collect(&s);
 
@@ -1302,8 +1372,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 
 	wt_status_prepare(&s);
 	git_config(git_commit_config, &s);
-	in_merge = file_exists(git_path("MERGE_HEAD"));
-	s.in_merge = in_merge;
+	determine_whence(&s);
 
 	if (s.use_color == -1)
 		s.use_color = git_use_color_default;
@@ -1340,7 +1409,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 
 		for (c = commit->parents; c; c = c->next)
 			pptr = &commit_list_insert(c->item, pptr)->next;
-	} else if (in_merge) {
+	} else if (whence == FROM_MERGE) {
 		struct strbuf m = STRBUF_INIT;
 		FILE *fp;
 
@@ -1369,7 +1438,9 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 			parents = reduce_heads(parents);
 	} else {
 		if (!reflog_msg)
-			reflog_msg = "commit";
+			reflog_msg = (whence == FROM_CHERRY_PICK)
+					? "commit (cherry-pick)"
+					: "commit";
 		pptr = &commit_list_insert(lookup_commit(head_sha1), pptr)->next;
 	}
 
diff --git a/builtin/revert.c b/builtin/revert.c
index deecaab..c57b872 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -3,7 +3,6 @@
 #include "object.h"
 #include "commit.h"
 #include "tag.h"
-#include "wt-status.h"
 #include "run-command.h"
 #include "exec_cmd.h"
 #include "utf8.h"
@@ -198,56 +197,6 @@ static void add_message_to_msg(struct strbuf *msgbuf, const char *message)
 	strbuf_addstr(msgbuf, p);
 }
 
-static void set_author_ident_env(const char *message)
-{
-	const char *p = message;
-	if (!p)
-		die ("Could not read commit message of %s",
-				sha1_to_hex(commit->object.sha1));
-	while (*p && *p != '\n') {
-		const char *eol;
-
-		for (eol = p; *eol && *eol != '\n'; eol++)
-			; /* do nothing */
-		if (!prefixcmp(p, "author ")) {
-			char *line, *pend, *email, *timestamp;
-
-			p += 7;
-			line = xmemdupz(p, eol - p);
-			email = strchr(line, '<');
-			if (!email)
-				die ("Could not extract author email from %s",
-					sha1_to_hex(commit->object.sha1));
-			if (email == line)
-				pend = line;
-			else
-				for (pend = email; pend != line + 1 &&
-						isspace(pend[-1]); pend--);
-					; /* do nothing */
-			*pend = '\0';
-			email++;
-			timestamp = strchr(email, '>');
-			if (!timestamp)
-				die ("Could not extract author time from %s",
-					sha1_to_hex(commit->object.sha1));
-			*timestamp = '\0';
-			for (timestamp++; *timestamp && isspace(*timestamp);
-					timestamp++)
-				; /* do nothing */
-			setenv("GIT_AUTHOR_NAME", line, 1);
-			setenv("GIT_AUTHOR_EMAIL", email, 1);
-			setenv("GIT_AUTHOR_DATE", timestamp, 1);
-			free(line);
-			return;
-		}
-		p = eol;
-		if (*p == '\n')
-			p++;
-	}
-	die ("No author information found in %s",
-			sha1_to_hex(commit->object.sha1));
-}
-
 static void write_cherry_pick_head(void)
 {
 	int fd;
@@ -290,9 +239,7 @@ static void print_advice(void)
 
 	advise("after resolving the conflicts, mark the corrected paths");
 	advise("with 'git add <paths>' or 'git rm <paths>'");
-
-	if (action == CHERRY_PICK)
-		advise("and commit the result with 'git commit -c CHERRY_PICK_HEAD'");
+	advise("and commit the result with 'git commit'");
 }
 
 static void write_message(struct strbuf *msgbuf, const char *filename)
@@ -518,7 +465,6 @@ static int do_pick_commit(void)
 		base_label = msg.parent_label;
 		next = commit;
 		next_label = msg.label;
-		set_author_ident_env(msg.message);
 		add_message_to_msg(&msgbuf, msg.message);
 		if (no_replay) {
 			strbuf_addstr(&msgbuf, "(cherry picked from commit ");
diff --git a/t/t3507-cherry-pick-conflict.sh b/t/t3507-cherry-pick-conflict.sh
index e0bf356..9574180 100755
--- a/t/t3507-cherry-pick-conflict.sh
+++ b/t/t3507-cherry-pick-conflict.sh
@@ -52,7 +52,7 @@ test_expect_success 'advice from failed cherry-pick' "
 	error: could not apply \$picked... picked
 	hint: after resolving the conflicts, mark the corrected paths
 	hint: with 'git add <paths>' or 'git rm <paths>'
-	hint: and commit the result with 'git commit -c CHERRY_PICK_HEAD'
+	hint: and commit the result with 'git commit'
 	EOF
 	test_must_fail git cherry-pick picked 2>actual &&
 
diff --git a/t/t7509-commit.sh b/t/t7509-commit.sh
index 77b6920..b61fd3c 100755
--- a/t/t7509-commit.sh
+++ b/t/t7509-commit.sh
@@ -157,4 +157,33 @@ test_expect_success '--reset-author should be rejected without -c/-C/--amend' '
 	test_must_fail git commit -a --reset-author -m done
 '
 
+test_expect_success 'commit respects CHERRY_PICK_HEAD and MERGE_MSG' '
+	echo "cherry-pick 1a" >>foo &&
+	test_tick &&
+	git commit -am "cherry-pick 1" --author="Cherry <cherry@pick.er>" &&
+	git tag cherry-pick-head &&
+	git rev-parse cherry-pick-head >.git/CHERRY_PICK_HEAD &&
+	echo "This is a MERGE_MSG" >.git/MERGE_MSG &&
+	echo "cherry-pick 1b" >>foo &&
+	test_tick &&
+	git commit -a &&
+	author_header cherry-pick-head >expect &&
+	author_header HEAD >actual &&
+	test_cmp expect actual &&
+
+	echo "This is a MERGE_MSG" >expect &&
+	message_body HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--reset-author with CHERRY_PICK_HEAD' '
+	git rev-parse cherry-pick-head >.git/CHERRY_PICK_HEAD &&
+	echo "cherry-pick 2" >>foo &&
+	test_tick &&
+	git commit -am "cherry-pick 2" --reset-author &&
+	echo "author $GIT_AUTHOR_NAME <$GIT_AUTHOR_EMAIL> $GIT_AUTHOR_DATE" >expect &&
+	author_header HEAD >actual &&
+	test_cmp expect actual
+'
+
 test_done
diff --git a/wt-status.c b/wt-status.c
index 123582b..fbaaf54 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -60,7 +60,7 @@ static void wt_status_print_unmerged_header(struct wt_status *s)
 	color_fprintf_ln(s->fp, c, "# Unmerged paths:");
 	if (!advice_status_hints)
 		return;
-	if (s->in_merge)
+	if (s->whence != FROM_COMMIT)
 		;
 	else if (!s->is_initial)
 		color_fprintf_ln(s->fp, c, "#   (use \"git reset %s <file>...\" to unstage)", s->reference);
@@ -77,7 +77,7 @@ static void wt_status_print_cached_header(struct wt_status *s)
 	color_fprintf_ln(s->fp, c, "# Changes to be committed:");
 	if (!advice_status_hints)
 		return;
-	if (s->in_merge)
+	if (s->whence != FROM_COMMIT)
 		; /* NEEDSWORK: use "git reset --unresolve"??? */
 	else if (!s->is_initial)
 		color_fprintf_ln(s->fp, c, "#   (use \"git reset %s <file>...\" to unstage)", s->reference);
diff --git a/wt-status.h b/wt-status.h
index 20b17cf..cec482a 100644
--- a/wt-status.h
+++ b/wt-status.h
@@ -24,6 +24,13 @@ enum untracked_status_type {
 	SHOW_ALL_UNTRACKED_FILES
 };
 
+/* from where does this commit originate */
+enum commit_whence {
+	FROM_COMMIT,     /* normal */
+	FROM_MERGE,      /* commit came from merge */
+	FROM_CHERRY_PICK /* commit came from cherry-pick */
+};
+
 struct wt_status_change_data {
 	int worktree_status;
 	int index_status;
@@ -40,7 +47,7 @@ struct wt_status {
 	const char **pathspec;
 	int verbose;
 	int amend;
-	int in_merge;
+	enum commit_whence whence;
 	int nowarn;
 	int use_color;
 	int relative_paths;
-- 
1.7.4.1.51.g615e0