Add a command "fixup" to rebase --interactive

The command is like "squash", except that it discards the commit message
of the corresponding commit.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-rebase.txt

@@ -382,9 +382,12 @@ If you just want to edit the commit message for a commit, replace the
 command "pick" with the command "reword".
 
 If you want to fold two or more commits into one, replace the command
-"pick" with "squash" for the second and subsequent commit.  If the
-commits had different authors, it will attribute the squashed commit to
-the author of the first commit.
+"pick" for the second and subsequent commits with "squash" or "fixup".
+If the commits had different authors, the folded commit will be
+attributed to the author of the first commit.  The suggested commit
+message for the folded commit is the concatenation of the commit
+messages of the first commit and of those with the "squash" command,
+but omits the commit messages of commits with the "fixup" command.
 
 'git-rebase' will stop when "pick" has been replaced with "edit" or
 when a command fails due to merge errors. When you are done editing
@@ -512,8 +515,8 @@ Easy case: The changes are literally the same.::
 Hard case: The changes are not the same.::
 
 	This happens if the 'subsystem' rebase had conflicts, or used
-	`\--interactive` to omit, edit, or squash commits; or if the
-	upstream used one of `commit \--amend`, `reset`, or
+	`\--interactive` to omit, edit, squash, or fixup commits; or
+	if the upstream used one of `commit \--amend`, `reset`, or
 	`filter-branch`.
 
 

git-rebase--interactive.sh

@@ -302,7 +302,10 @@ nth_string () {
 
 make_squash_message () {
 	if test -f "$SQUASH_MSG"; then
-		COUNT=$(($(sed -n "s/^# This is [^0-9]*\([1-9][0-9]*\).*/\1/p" \
+		# We want to be careful about matching only the commit
+		# message comment lines generated by this function.
+		# "[snrt][tdh]" matches the nth_string endings.
+		COUNT=$(($(sed -n "s/^# Th[^0-9]*\([1-9][0-9]*\)[snrt][tdh] commit message.*:/\1/p" \
 			< "$SQUASH_MSG" | sed -ne '$p')+1))
 		echo "# This is a combination of $COUNT commits."
 		sed -e 1d -e '2,/^./{
@@ -315,10 +318,23 @@ make_squash_message () {
 		echo
 		git cat-file commit HEAD | sed -e '1,/^$/d'
 	fi
-	echo
-	echo "# This is the $(nth_string $COUNT) commit message:"
-	echo
-	git cat-file commit $1 | sed -e '1,/^$/d'
+	case $1 in
+	squash)
+		echo
+		echo "# This is the $(nth_string $COUNT) commit message:"
+		echo
+		git cat-file commit $2 | sed -e '1,/^$/d'
+		;;
+	fixup)
+		echo
+		echo "# The $(nth_string $COUNT) commit message will be skipped:"
+		echo
+		# Comment the lines of the commit message out using
+		# "#	" rather than "# " to make them less likely to
+		# confuse the sed regexp above.
+		git cat-file commit $2 | sed -e '1,/^$/d' -e 's/^/#	/'
+		;;
+	esac
 }
 
 peek_next_command () {
@@ -367,20 +383,28 @@ do_next () {
 		warn
 		exit 0
 		;;
-	squash|s)
-		comment_for_reflog squash
+	squash|s|fixup|f)
+		case "$command" in
+		squash|s)
+			squash_style=squash
+			;;
+		fixup|f)
+			squash_style=fixup
+			;;
+		esac
+		comment_for_reflog $squash_style
 
 		test -f "$DONE" && has_action "$DONE" ||
-			die "Cannot 'squash' without a previous commit"
+			die "Cannot '$squash_style' without a previous commit"
 
 		mark_action_done
-		make_squash_message $sha1 > "$MSG"
+		make_squash_message $squash_style $sha1 > "$MSG"
 		failed=f
 		author_script=$(get_author_ident_from_commit HEAD)
 		output git reset --soft HEAD^
 		pick_one -n $sha1 || failed=t
 		case "$(peek_next_command)" in
-		squash|s)
+		squash|s|fixup|f)
 			USE_OUTPUT=output
 			MSG_OPT=-F
 			EDIT_OR_FILE="$MSG"
@@ -768,6 +792,7 @@ first and then run 'git rebase --continue' again."
 #  r, reword = use commit, but edit the commit message
 #  e, edit = use commit, but stop for amending
 #  s, squash = use commit, but meld into previous commit
+#  f, fixup = like "squash", but discard this commit's log message
 #
 # If you remove a line here THAT COMMIT WILL BE LOST.
 # However, if you remove everything, the rebase will be aborted.

t/lib-rebase.sh

@@ -9,8 +9,9 @@
 #
 #	"[<lineno1>] [<lineno2>]..."
 #
-#   If a line number is prefixed with "squash", "edit", or "reword", the
-#   respective line's command will be replaced with the specified one.
+#   If a line number is prefixed with "squash", "fixup", "edit", or
+#   "reword", the respective line's command will be replaced with the
+#   specified one.
 
 set_fake_editor () {
 	echo "#!$SHELL_PATH" >fake-editor.sh
@@ -32,7 +33,7 @@ cat "$1".tmp
 action=pick
 for line in $FAKE_LINES; do
 	case $line in
-	squash|edit|reword)
+	squash|fixup|edit|reword)
 		action="$line";;
 	*)
 		echo sed -n "${line}s/^pick/$action/p"

t/t3404-rebase-interactive.sh

@@ -235,6 +235,36 @@ test_expect_success 'multi-squash only fires up editor once' '
 	test 1 = $(git show | grep ONCE | wc -l)
 '
 
+test_expect_success 'multi-fixup only fires up editor once' '
+	git checkout -b multi-fixup E &&
+	base=$(git rev-parse HEAD~4) &&
+	FAKE_COMMIT_AMEND="ONCE" FAKE_LINES="1 fixup 2 fixup 3 fixup 4" \
+		git rebase -i $base &&
+	test $base = $(git rev-parse HEAD^) &&
+	test 1 = $(git show | grep ONCE | wc -l) &&
+	git checkout to-be-rebased &&
+	git branch -D multi-fixup
+'
+
+cat > expect-squash-fixup << EOF
+B
+
+D
+
+ONCE
+EOF
+
+test_expect_success 'squash and fixup generate correct log messages' '
+	git checkout -b squash-fixup E &&
+	base=$(git rev-parse HEAD~4) &&
+	FAKE_COMMIT_AMEND="ONCE" FAKE_LINES="1 fixup 2 squash 3 fixup 4" \
+		git rebase -i $base &&
+	git cat-file commit HEAD | sed -e 1,/^\$/d > actual-squash-fixup &&
+	test_cmp expect-squash-fixup actual-squash-fixup &&
+	git checkout to-be-rebased &&
+	git branch -D squash-fixup
+'
+
 test_expect_success 'squash works as expected' '
 	for n in one two three four
 	do