git bisect start on a tag revision fails

git bisect start on a tag revision fails

[Reece Dunn]

Hi,

When hunting bugs with the wine source code
(git://source.winehq.org/git/wine.git), both Dan Kegel and I have
found the following berhaviour with git bisect:

$ git checkout wine-0.9.54
HEAD is now at 8f954cc... Release 0.9.54.
$ git bisect start
fatal: ref HEAD is not a symbolic ref
Bad HEAD - I need a symbolic ref

Whereas doing:

$ git checkout master
$ git bisect start

then:

$ git checkout wine-0.9.54
$ git bisect good

works.

Is it possible to have bisect support non-symbolic refs?

- Reece

[PATCH] bisect: allow starting with a detached HEAD

[Johannes Schindelin]

Instead of insisting on a symbolic ref, bisect now accepts detached
HEADs, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---

	On Sun, 10 Feb 2008, Reece Dunn wrote:

	> When hunting bugs with the wine source code
	> (git://source.winehq.org/git/wine.git), both Dan Kegel and I have
	> found the following berhaviour with git bisect:
	> 
	> $ git checkout wine-0.9.54
	> HEAD is now at 8f954cc... Release 0.9.54.
	> $ git bisect start
	> fatal: ref HEAD is not a symbolic ref
	> Bad HEAD - I need a symbolic ref

	Woohoo!  test_expect_failure is nice... it tells you about
	a fixed behaviour, too!

	(Of course, I changed it to test_expect_success now...)

 git-bisect.sh               |    8 ++++++--
 t/t6030-bisect-porcelain.sh |   12 ++++++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/git-bisect.sh b/git-bisect.sh
index 5385249..393fa35 100755
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -26,6 +26,9 @@ OPTIONS_SPEC=
 . git-sh-setup
 require_work_tree
 
+_x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
+_x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
+
 sq() {
 	@@PERL@@ -e '
 		for (@ARGV) {
@@ -60,7 +63,8 @@ bisect_start() {
 	# top-of-line master first!
 	#
 	head=$(GIT_DIR="$GIT_DIR" git symbolic-ref HEAD) ||
-	die "Bad HEAD - I need a symbolic ref"
+	head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) ||
+	die "Bad HEAD - I need a HEAD"
 	case "$head" in
 	refs/heads/bisect)
 		if [ -s "$GIT_DIR/head-name" ]; then
@@ -70,7 +74,7 @@ bisect_start() {
 		fi
 		git checkout $branch || exit
 		;;
-	refs/heads/*)
+	refs/heads/*|$_x40)
 		[ -s "$GIT_DIR/head-name" ] && die "won't bisect on seeked tree"
 		echo "${head#refs/heads/}" >"$GIT_DIR/head-name"
 		;;
diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
index 2ba4b00..ec71123 100755
--- a/t/t6030-bisect-porcelain.sh
+++ b/t/t6030-bisect-porcelain.sh
@@ -254,6 +254,18 @@ test_expect_success 'bisect run & skip: find first bad' '
 	grep "$HASH6 is first bad commit" my_bisect_log.txt
 '
 
+test_expect_success 'bisect starting with a detached HEAD' '
+
+	git bisect reset &&
+	git checkout master^ &&
+	HEAD=$(git rev-parse --verify HEAD) &&
+	git bisect start &&
+	test $HEAD = $(cat .git/head-name) &&
+	git bisect reset &&
+	test $HEAD = $(git rev-parse --verify HEAD)
+
+'
+
 #
 #
 test_done
-- 
1.5.4.1264.gb53928