Merge branch 'ad/bisect-cleanup'

Code and documentation clean-up to "git bisect".

* ad/bisect-cleanup:
  bisect: don't mix option parsing and non-trivial code
  bisect: simplify the addition of new bisect terms
  bisect: replace hardcoded "bad|good" by variables
  Documentation/bisect: revise overall content
  Documentation/bisect: move getting help section to the end
  bisect: correction of typo

6 files changed, 266 insertions, 116 deletions

diff --git a/Documentation/git-bisect.txt b/Documentation/git-bisect.txt
index 4cb52a7302..e97f2de21b 100644
--- a/Documentation/git-bisect.txt
+++ b/Documentation/git-bisect.txt
@@ -3,7 +3,7 @@ git-bisect(1)
 
 NAME
 ----
-git-bisect - Find by binary search the change that introduced a bug
+git-bisect - Use binary search to find the commit that introduced a bug
 
 
 SYNOPSIS
@@ -16,7 +16,6 @@ DESCRIPTION
 The command takes various subcommands, and different options depending
 on the subcommand:
 
- git bisect help
  git bisect start [--no-checkout] [<bad> [<good>...]] [--] [<paths>...]
  git bisect bad [<rev>]
  git bisect good [<rev>...]
@@ -26,64 +25,71 @@ on the subcommand:
  git bisect replay <logfile>
  git bisect log
  git bisect run <cmd>...
+ git bisect help
 
-This command uses 'git rev-list --bisect' to help drive the
-binary search process to find which change introduced a bug, given an
-old "good" commit object name and a later "bad" commit object name.
-
-Getting help
-~~~~~~~~~~~~
-
-Use "git bisect" to get a short usage description, and "git bisect
-help" or "git bisect -h" to get a long usage description.
+This command uses a binary search algorithm to find which commit in
+your project's history introduced a bug. You use it by first telling
+it a "bad" commit that is known to contain the bug, and a "good"
+commit that is known to be before the bug was introduced. Then `git
+bisect` picks a commit between those two endpoints and asks you
+whether the selected commit is "good" or "bad". It continues narrowing
+down the range until it finds the exact commit that introduced the
+change.
 
 Basic bisect commands: start, bad, good
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Using the Linux kernel tree as an example, basic use of the bisect
-command is as follows:
+As an example, suppose you are trying to find the commit that broke a
+feature that was known to work in version `v2.6.13-rc2` of your
+project. You start a bisect session as follows:
 
 ------------------------------------------------
 $ git bisect start
 $ git bisect bad                 # Current version is bad
-$ git bisect good v2.6.13-rc2    # v2.6.13-rc2 was the last version
-                                 # tested that was good
+$ git bisect good v2.6.13-rc2    # v2.6.13-rc2 is known to be good
 ------------------------------------------------
 
-When you have specified at least one bad and one good version, the
-command bisects the revision tree and outputs something similar to
-the following:
+Once you have specified at least one bad and one good commit, `git
+bisect` selects a commit in the middle of that range of history,
+checks it out, and outputs something similar to the following:
 
 ------------------------------------------------
-Bisecting: 675 revisions left to test after this
+Bisecting: 675 revisions left to test after this (roughly 10 steps)
 ------------------------------------------------
 
-The state in the middle of the set of revisions is then checked out.
-You would now compile that kernel and boot it. If the booted kernel
-works correctly, you would then issue the following command:
+You should now compile the checked-out version and test it. If that
+version works correctly, type
 
 ------------------------------------------------
-$ git bisect good			# this one is good
+$ git bisect good
 ------------------------------------------------
 
-The output of this command would be something similar to the following:
+If that version is broken, type
 
 ------------------------------------------------
-Bisecting: 337 revisions left to test after this
+$ git bisect bad
 ------------------------------------------------
 
-You keep repeating this process, compiling the tree, testing it, and
-depending on whether it is good or bad issuing the command "git bisect good"
-or "git bisect bad" to ask for the next bisection.
+Then `git bisect` will respond with something like
+
+------------------------------------------------
+Bisecting: 337 revisions left to test after this (roughly 9 steps)
+------------------------------------------------
+
+Keep repeating the process: compile the tree, test it, and depending
+on whether it is good or bad run `git bisect good` or `git bisect bad`
+to ask for the next commit that needs testing.
+
+Eventually there will be no more revisions left to inspect, and the
+command will print out a description of the first bad commit. The
+reference `refs/bisect/bad` will be left pointing at that commit.
 
-Eventually there will be no more revisions left to bisect, and you
-will have been left with the first bad kernel revision in "refs/bisect/bad".
 
 Bisect reset
 ~~~~~~~~~~~~
 
 After a bisect session, to clean up the bisection state and return to
-the original HEAD (i.e., to quit bisecting), issue the following command:
+the original HEAD, issue the following command:
 
 ------------------------------------------------
 $ git bisect reset
@@ -100,9 +106,10 @@ instead:
 $ git bisect reset <commit>
 ------------------------------------------------
 
-For example, `git bisect reset HEAD` will leave you on the current
-bisection commit and avoid switching commits at all, while `git bisect
-reset bisect/bad` will check out the first bad revision.
+For example, `git bisect reset bisect/bad` will check out the first
+bad revision, while `git bisect reset HEAD` will leave you on the
+current bisection commit and avoid switching commits at all.
+
 
 Bisect visualize
 ~~~~~~~~~~~~~~~~
@@ -147,17 +154,17 @@ $ git bisect replay that-file
 Avoiding testing a commit
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 
-If, in the middle of a bisect session, you know that the next suggested
-revision is not a good one to test (e.g. the change the commit
-introduces is known not to work in your environment and you know it
-does not have anything to do with the bug you are chasing), you may
-want to find a nearby commit and try that instead.
+If, in the middle of a bisect session, you know that the suggested
+revision is not a good one to test (e.g. it fails to build and you
+know that the failure does not have anything to do with the bug you
+are chasing), you can manually select a nearby commit and test that
+one instead.
 
 For example:
 
 ------------
 $ git bisect good/bad			# previous round was good or bad.
-Bisecting: 337 revisions left to test after this
+Bisecting: 337 revisions left to test after this (roughly 9 steps)
 $ git bisect visualize			# oops, that is uninteresting.
 $ git reset --hard HEAD~3		# try 3 revisions before what
 					# was suggested
@@ -169,18 +176,19 @@ the revision as good or bad in the usual manner.
 Bisect skip
 ~~~~~~~~~~~~
 
-Instead of choosing by yourself a nearby commit, you can ask Git
-to do it for you by issuing the command:
+Instead of choosing a nearby commit by yourself, you can ask Git to do
+it for you by issuing the command:
 
 ------------
 $ git bisect skip                 # Current version cannot be tested
 ------------
 
-But Git may eventually be unable to tell the first bad commit among
-a bad commit and one or more skipped commits.
+However, if you skip a commit adjacent to the one you are looking for,
+Git will be unable to tell exactly which of those commits was the
+first bad one.
 
-You can even skip a range of commits, instead of just one commit,
-using the "'<commit1>'..'<commit2>'" notation. For example:
+You can also skip a range of commits, instead of just one commit,
+using range notation. For example:
 
 ------------
 $ git bisect skip v2.5..v2.6
@@ -196,8 +204,8 @@ would issue the command:
 $ git bisect skip v2.5 v2.5..v2.6
 ------------
 
-This tells the bisect process that the commits between `v2.5` included
-and `v2.6` included should be skipped.
+This tells the bisect process that the commits between `v2.5` and
+`v2.6` (inclusive) should be skipped.
 
 
 Cutting down bisection by giving more parameters to bisect start
@@ -231,14 +239,14 @@ or bad, you can bisect by issuing the command:
 $ git bisect run my_script arguments
 ------------
 
-Note that the script (`my_script` in the above example) should
-exit with code 0 if the current source code is good, and exit with a
-code between 1 and 127 (inclusive), except 125, if the current
-source code is bad.
+Note that the script (`my_script` in the above example) should exit
+with code 0 if the current source code is good/old, and exit with a
+code between 1 and 127 (inclusive), except 125, if the current source
+code is bad/new.
 
 Any other exit code will abort the bisect process. It should be noted
-that a program that terminates via "exit(-1)" leaves $? = 255, (see the
-exit(3) manual page), as the value is chopped with "& 0377".
+that a program that terminates via `exit(-1)` leaves $? = 255, (see the
+exit(3) manual page), as the value is chopped with `& 0377`.
 
 The special exit code 125 should be used when the current source code
 cannot be tested. If the script exits with this code, the current
@@ -247,7 +255,7 @@ as the highest sensible value to use for this purpose, because 126 and 127
 are used by POSIX shells to signal specific error status (127 is for
 command not found, 126 is for command found but not executable---these
 details do not matter, as they are normal errors in the script, as far as
-"bisect run" is concerned).
+`bisect run` is concerned).
 
 You may often find that during a bisect session you want to have
 temporary modifications (e.g. s/#define DEBUG 0/#define DEBUG 1/ in a
@@ -260,7 +268,7 @@ next revision to test, the script can apply the patch
 before compiling, run the real test, and afterwards decide if the
 revision (possibly with the needed patch) passed the test and then
 rewind the tree to the pristine state.  Finally the script should exit
-with the status of the real test to let the "git bisect run" command loop
+with the status of the real test to let the `git bisect run` command loop
 determine the eventual outcome of the bisect session.
 
 OPTIONS
@@ -307,12 +315,12 @@ $ git bisect run ~/test.sh
 $ git bisect reset                   # quit the bisect session
 ------------
 +
-Here we use a "test.sh" custom script. In this script, if "make"
+Here we use a `test.sh` custom script. In this script, if `make`
 fails, we skip the current commit.
-"check_test_case.sh" should "exit 0" if the test case passes,
-and "exit 1" otherwise.
+`check_test_case.sh` should `exit 0` if the test case passes,
+and `exit 1` otherwise.
 +
-It is safer if both "test.sh" and "check_test_case.sh" are
+It is safer if both `test.sh` and `check_test_case.sh` are
 outside the repository to prevent interactions between the bisect,
 make and test processes and the scripts.
 
@@ -379,6 +387,11 @@ In this case, when 'git bisect run' finishes, bisect/bad will refer to a commit
 has at least one parent whose reachable graph is fully traversable in the sense
 required by 'git pack objects'.
 
+Getting help
+~~~~~~~~~~~~
+
+Use `git bisect` to get a short usage description, and `git bisect
+help` or `git bisect -h` to get a long usage description.
 
 SEE ALSO
 --------
diff --git a/bisect.c b/bisect.c
index 03d5cd9454..857cf59aa3 100644
--- a/bisect.c
+++ b/bisect.c
@@ -21,6 +21,9 @@ static const char *argv_checkout[] = {"checkout", "-q", NULL, "--", NULL};
 static const char *argv_show_branch[] = {"show-branch", NULL, NULL};
 static const char *argv_update_ref[] = {"update-ref", "--no-deref", "BISECT_HEAD", NULL, NULL};
 
+static const char *term_bad;
+static const char *term_good;
+
 /* Remember to update object flag allocation in object.h */
 #define COUNTED		(1u<<16)
 
@@ -403,15 +406,21 @@ struct commit_list *find_bisection(struct commit_list *list,
 static int register_ref(const char *refname, const struct object_id *oid,
 			int flags, void *cb_data)
 {
-	if (!strcmp(refname, "bad")) {
+	struct strbuf good_prefix = STRBUF_INIT;
+	strbuf_addstr(&good_prefix, term_good);
+	strbuf_addstr(&good_prefix, "-");
+
+	if (!strcmp(refname, term_bad)) {
 		current_bad_oid = xmalloc(sizeof(*current_bad_oid));
 		oidcpy(current_bad_oid, oid);
-	} else if (starts_with(refname, "good-")) {
+	} else if (starts_with(refname, good_prefix.buf)) {
 		sha1_array_append(&good_revs, oid->hash);
 	} else if (starts_with(refname, "skip-")) {
 		sha1_array_append(&skipped_revs, oid->hash);
 	}
 
+	strbuf_release(&good_prefix);
+
 	return 0;
 }
 
@@ -634,7 +643,7 @@ static void exit_if_skipped_commits(struct commit_list *tried,
 		return;
 
 	printf("There are only 'skip'ped commits left to test.\n"
-	       "The first bad commit could be any of:\n");
+	       "The first %s commit could be any of:\n", term_bad);
 	print_commit_list(tried, "%s\n", "%s\n");
 	if (bad)
 		printf("%s\n", oid_to_hex(bad));
@@ -732,18 +741,24 @@ static void handle_bad_merge_base(void)
 	if (is_expected_rev(current_bad_oid)) {
 		char *bad_hex = oid_to_hex(current_bad_oid);
 		char *good_hex = join_sha1_array_hex(&good_revs, ' ');
-
-		fprintf(stderr, "The merge base %s is bad.\n"
-			"This means the bug has been fixed "
-			"between %s and [%s].\n",
-			bad_hex, bad_hex, good_hex);
-
+		if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
+			fprintf(stderr, "The merge base %s is bad.\n"
+				"This means the bug has been fixed "
+				"between %s and [%s].\n",
+				bad_hex, bad_hex, good_hex);
+		} else {
+			fprintf(stderr, "The merge base %s is %s.\n"
+				"This means the first '%s' commit is "
+				"between %s and [%s].\n",
+				bad_hex, term_bad, term_good, bad_hex, good_hex);
+		}
 		exit(3);
 	}
 
-	fprintf(stderr, "Some good revs are not ancestor of the bad rev.\n"
+	fprintf(stderr, "Some %s revs are not ancestor of the %s rev.\n"
 		"git bisect cannot work properly in this case.\n"
-		"Maybe you mistake good and bad revs?\n");
+		"Maybe you mistook %s and %s revs?\n",
+		term_good, term_bad, term_good, term_bad);
 	exit(1);
 }
 
@@ -755,10 +770,10 @@ static void handle_skipped_merge_base(const unsigned char *mb)
 
 	warning("the merge base between %s and [%s] "
 		"must be skipped.\n"
-		"So we cannot be sure the first bad commit is "
+		"So we cannot be sure the first %s commit is "
 		"between %s and %s.\n"
 		"We continue anyway.",
-		bad_hex, good_hex, mb_hex, bad_hex);
+		bad_hex, good_hex, term_bad, mb_hex, bad_hex);
 	free(good_hex);
 }
 
@@ -839,7 +854,7 @@ static void check_good_are_ancestors_of_bad(const char *prefix, int no_checkout)
 	int fd;
 
 	if (!current_bad_oid)
-		die("a bad revision is needed");
+		die("a %s revision is needed", term_bad);
 
 	/* Check if file BISECT_ANCESTORS_OK exists. */
 	if (!stat(filename, &st) && S_ISREG(st.st_mode))
@@ -890,6 +905,36 @@ static void show_diff_tree(const char *prefix, struct commit *commit)
 }
 
 /*
+ * The terms used for this bisect session are stored in BISECT_TERMS.
+ * We read them and store them to adapt the messages accordingly.
+ * Default is bad/good.
+ */
+void read_bisect_terms(const char **read_bad, const char **read_good)
+{
+	struct strbuf str = STRBUF_INIT;
+	const char *filename = git_path("BISECT_TERMS");
+	FILE *fp = fopen(filename, "r");
+
+	if (!fp) {
+		if (errno == ENOENT) {
+			*read_bad = "bad";
+			*read_good = "good";
+			return;
+		} else {
+			die("could not read file '%s': %s", filename,
+				strerror(errno));
+		}
+	} else {
+		strbuf_getline(&str, fp, '\n');
+		*read_bad = strbuf_detach(&str, NULL);
+		strbuf_getline(&str, fp, '\n');
+		*read_good = strbuf_detach(&str, NULL);
+	}
+	strbuf_release(&str);
+	fclose(fp);
+}
+
+/*
  * We use the convention that exiting with an exit code 10 means that
  * the bisection process finished successfully.
  * In this case the calling shell script should exit 0.
@@ -905,6 +950,7 @@ int bisect_next_all(const char *prefix, int no_checkout)
 	const unsigned char *bisect_rev;
 	char bisect_rev_hex[GIT_SHA1_HEXSZ + 1];
 
+	read_bisect_terms(&term_bad, &term_good);
 	if (read_bisect_refs())
 		die("reading bisect refs failed");
 
@@ -926,8 +972,10 @@ int bisect_next_all(const char *prefix, int no_checkout)
 		 */
 		exit_if_skipped_commits(tried, NULL);
 
-		printf("%s was both good and bad\n",
-		       oid_to_hex(current_bad_oid));
+		printf("%s was both %s and %s\n",
+		       oid_to_hex(current_bad_oid),
+		       term_good,
+		       term_bad);
 		exit(1);
 	}
 
@@ -942,7 +990,8 @@ int bisect_next_all(const char *prefix, int no_checkout)
 
 	if (!hashcmp(bisect_rev, current_bad_oid->hash)) {
 		exit_if_skipped_commits(tried, current_bad_oid);
-		printf("%s is the first bad commit\n", bisect_rev_hex);
+		printf("%s is the first %s commit\n", bisect_rev_hex,
+			term_bad);
 		show_diff_tree(prefix, revs.commits->item);
 		/* This means the bisection process succeeded. */
 		exit(10);
diff --git a/bisect.h b/bisect.h
index 2a6c831f3e..acd12ef802 100644
--- a/bisect.h
+++ b/bisect.h
@@ -26,4 +26,6 @@ extern int bisect_next_all(const char *prefix, int no_checkout);
 
 extern int estimate_bisect_steps(int all);
 
+extern void read_bisect_terms(const char **bad, const char **good);
+
 #endif
diff --git a/git-bisect.sh b/git-bisect.sh
index ae3fec22c4..ea63223ab3 100755
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -32,6 +32,8 @@ OPTIONS_SPEC=
 
 _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"
+TERM_BAD=bad
+TERM_GOOD=good
 
 bisect_head()
 {
@@ -75,6 +77,8 @@ bisect_start() {
 	orig_args=$(git rev-parse --sq-quote "$@")
 	bad_seen=0
 	eval=''
+	must_write_terms=0
+	revs=''
 	if test "z$(git rev-parse --is-bare-repository)" != zfalse
 	then
 		mode=--no-checkout
@@ -99,16 +103,27 @@ bisect_start() {
 				die "$(eval_gettext "'\$arg' does not appear to be a valid revision")"
 				break
 			}
-			case $bad_seen in
-			0) state='bad' ; bad_seen=1 ;;
-			*) state='good' ;;
-			esac
-			eval="$eval bisect_write '$state' '$rev' 'nolog' &&"
+			revs="$revs $rev"
 			shift
 			;;
 		esac
 	done
 
+	for rev in $revs
+	do
+		# The user ran "git bisect start <sha1>
+		# <sha1>", hence did not explicitly specify
+		# the terms, but we are already starting to
+		# set references named with the default terms,
+		# and won't be able to change afterwards.
+		must_write_terms=1
+
+		case $bad_seen in
+		0) state=$TERM_BAD ; bad_seen=1 ;;
+		*) state=$TERM_GOOD ;;
+		esac
+		eval="$eval bisect_write '$state' '$rev' 'nolog' &&"
+	done
 	#
 	# Verify HEAD.
 	#
@@ -170,6 +185,10 @@ bisect_start() {
 	} &&
 	git rev-parse --sq-quote "$@" >"$GIT_DIR/BISECT_NAMES" &&
 	eval "$eval true" &&
+	if test $must_write_terms -eq 1
+	then
+		write_terms "$TERM_BAD" "$TERM_GOOD"
+	fi &&
 	echo "git bisect start$orig_args" >>"$GIT_DIR/BISECT_LOG" || exit
 	#
 	# Check if we can proceed to the next bisect state.
@@ -184,9 +203,12 @@ bisect_write() {
 	rev="$2"
 	nolog="$3"
 	case "$state" in
-		bad)		tag="$state" ;;
-		good|skip)	tag="$state"-"$rev" ;;
-		*)		die "$(eval_gettext "Bad bisect_write argument: \$state")" ;;
+		"$TERM_BAD")
+			tag="$state" ;;
+		"$TERM_GOOD"|skip)
+			tag="$state"-"$rev" ;;
+		*)
+			die "$(eval_gettext "Bad bisect_write argument: \$state")" ;;
 	esac
 	git update-ref "refs/bisect/$tag" "$rev" || exit
 	echo "# $state: $(git show-branch $rev)" >>"$GIT_DIR/BISECT_LOG"
@@ -227,15 +249,16 @@ bisect_skip() {
 bisect_state() {
 	bisect_autostart
 	state=$1
+	check_and_set_terms $state
 	case "$#,$state" in
 	0,*)
 		die "$(gettext "Please call 'bisect_state' with at least one argument.")" ;;
-	1,bad|1,good|1,skip)
+	1,"$TERM_BAD"|1,"$TERM_GOOD"|1,skip)
 		rev=$(git rev-parse --verify $(bisect_head)) ||
 			die "$(gettext "Bad rev input: $(bisect_head)")"
 		bisect_write "$state" "$rev"
 		check_expected_revs "$rev" ;;
-	2,bad|*,good|*,skip)
+	2,"$TERM_BAD"|*,"$TERM_GOOD"|*,skip)
 		shift
 		hash_list=''
 		for rev in "$@"
@@ -249,8 +272,8 @@ bisect_state() {
 			bisect_write "$state" "$rev"
 		done
 		check_expected_revs $hash_list ;;
-	*,bad)
-		die "$(gettext "'git bisect bad' can take only one argument.")" ;;
+	*,"$TERM_BAD")
+		die "$(eval_gettext "'git bisect \$TERM_BAD' can take only one argument.")" ;;
 	*)
 		usage ;;
 	esac
@@ -259,21 +282,21 @@ bisect_state() {
 
 bisect_next_check() {
 	missing_good= missing_bad=
-	git show-ref -q --verify refs/bisect/bad || missing_bad=t
-	test -n "$(git for-each-ref "refs/bisect/good-*")" || missing_good=t
+	git show-ref -q --verify refs/bisect/$TERM_BAD || missing_bad=t
+	test -n "$(git for-each-ref "refs/bisect/$TERM_GOOD-*")" || missing_good=t
 
 	case "$missing_good,$missing_bad,$1" in
 	,,*)
-		: have both good and bad - ok
+		: have both $TERM_GOOD and $TERM_BAD - ok
 		;;
 	*,)
 		# do not have both but not asked to fail - just report.
 		false
 		;;
-	t,,good)
+	t,,"$TERM_GOOD")
 		# have bad but not good.  we could bisect although
 		# this is less optimum.
-		gettextln "Warning: bisecting only with a bad commit." >&2
+		eval_gettextln "Warning: bisecting only with a \$TERM_BAD commit." >&2
 		if test -t 0
 		then
 			# TRANSLATORS: Make sure to include [Y] and [n] in your
@@ -283,18 +306,20 @@ bisect_next_check() {
 			read yesno
 			case "$yesno" in [Nn]*) exit 1 ;; esac
 		fi
-		: bisect without good...
+		: bisect without $TERM_GOOD...
 		;;
 	*)
-
+		bad_syn=$(bisect_voc bad)
+		good_syn=$(bisect_voc good)
 		if test -s "$GIT_DIR/BISECT_START"
 		then
-			gettextln "You need to give me at least one good and one bad revision.
-(You can use \"git bisect bad\" and \"git bisect good\" for that.)" >&2
+
+			eval_gettextln "You need to give me at least one \$bad_syn and one \$good_syn revision.
+(You can use \"git bisect \$bad_syn\" and \"git bisect \$good_syn\" for that.)" >&2
 		else
-			gettextln "You need to start by \"git bisect start\".
-You then need to give me at least one good and one bad revision.
-(You can use \"git bisect bad\" and \"git bisect good\" for that.)" >&2
+			eval_gettextln "You need to start by \"git bisect start\".
+You then need to give me at least one \$good_syn and one \$bad_syn revision.
+(You can use \"git bisect \$bad_syn\" and \"git bisect \$good_syn\" for that.)" >&2
 		fi
 		exit 1 ;;
 	esac
@@ -307,7 +332,7 @@ bisect_auto_next() {
 bisect_next() {
 	case "$#" in 0) ;; *) usage ;; esac
 	bisect_autostart
-	bisect_next_check good
+	bisect_next_check $TERM_GOOD
 
 	# Perform all bisection computation, display and checkout
 	git bisect--helper --next-all $(test -f "$GIT_DIR/BISECT_HEAD" && echo --no-checkout)
@@ -316,18 +341,18 @@ bisect_next() {
 	# Check if we should exit because bisection is finished
 	if test $res -eq 10
 	then
-		bad_rev=$(git show-ref --hash --verify refs/bisect/bad)
+		bad_rev=$(git show-ref --hash --verify refs/bisect/$TERM_BAD)
 		bad_commit=$(git show-branch $bad_rev)
-		echo "# first bad commit: $bad_commit" >>"$GIT_DIR/BISECT_LOG"
+		echo "# first $TERM_BAD commit: $bad_commit" >>"$GIT_DIR/BISECT_LOG"
 		exit 0
 	elif test $res -eq 2
 	then
 		echo "# only skipped commits left to test" >>"$GIT_DIR/BISECT_LOG"
-		good_revs=$(git for-each-ref --format="%(objectname)" "refs/bisect/good-*")
-		for skipped in $(git rev-list refs/bisect/bad --not $good_revs)
+		good_revs=$(git for-each-ref --format="%(objectname)" "refs/bisect/$TERM_GOOD-*")
+		for skipped in $(git rev-list refs/bisect/$TERM_BAD --not $good_revs)
 		do
 			skipped_commit=$(git show-branch $skipped)
-			echo "# possible first bad commit: $skipped_commit" >>"$GIT_DIR/BISECT_LOG"
+			echo "# possible first $TERM_BAD commit: $skipped_commit" >>"$GIT_DIR/BISECT_LOG"
 		done
 		exit $res
 	fi
@@ -397,6 +422,7 @@ bisect_clean_state() {
 	rm -f "$GIT_DIR/BISECT_LOG" &&
 	rm -f "$GIT_DIR/BISECT_NAMES" &&
 	rm -f "$GIT_DIR/BISECT_RUN" &&
+	rm -f "$GIT_DIR/BISECT_TERMS" &&
 	# Cleanup head-name if it got left by an old version of git-bisect
 	rm -f "$GIT_DIR/head-name" &&
 	git update-ref -d --no-deref BISECT_HEAD &&
@@ -417,11 +443,13 @@ bisect_replay () {
 			rev="$command"
 			command="$bisect"
 		fi
+		get_terms
+		check_and_set_terms "$command"
 		case "$command" in
 		start)
 			cmd="bisect_start $rev"
 			eval "$cmd" ;;
-		good|bad|skip)
+		"$TERM_GOOD"|"$TERM_BAD"|skip)
 			bisect_write "$command" "$rev" ;;
 		*)
 			die "$(gettext "?? what are you talking about?")" ;;
@@ -455,9 +483,9 @@ exit code \$res from '\$command' is < 0 or >= 128" >&2
 			state='skip'
 		elif [ $res -gt 0 ]
 		then
-			state='bad'
+			state="$TERM_BAD"
 		else
-			state='good'
+			state="$TERM_GOOD"
 		fi
 
 		# We have to use a subshell because "bisect_state" can exit.
@@ -466,7 +494,7 @@ exit code \$res from '\$command' is < 0 or >= 128" >&2
 
 		cat "$GIT_DIR/BISECT_RUN"
 
-		if sane_grep "first bad commit could be any of" "$GIT_DIR/BISECT_RUN" \
+		if sane_grep "first $TERM_BAD commit could be any of" "$GIT_DIR/BISECT_RUN" \
 			>/dev/null
 		then
 			gettextln "bisect run cannot continue any more" >&2
@@ -480,7 +508,7 @@ exit code \$res from '\$command' is < 0 or >= 128" >&2
 			exit $res
 		fi
 
-		if sane_grep "is the first bad commit" "$GIT_DIR/BISECT_RUN" >/dev/null
+		if sane_grep "is the first $TERM_BAD commit" "$GIT_DIR/BISECT_RUN" >/dev/null
 		then
 			gettextln "bisect run success"
 			exit 0;
@@ -494,18 +522,62 @@ bisect_log () {
 	cat "$GIT_DIR/BISECT_LOG"
 }
 
+get_terms () {
+	if test -s "$GIT_DIR/BISECT_TERMS"
+	then
+		{
+		read TERM_BAD
+		read TERM_GOOD
+		} <"$GIT_DIR/BISECT_TERMS"
+	fi
+}
+
+write_terms () {
+	TERM_BAD=$1
+	TERM_GOOD=$2
+	printf '%s\n%s\n' "$TERM_BAD" "$TERM_GOOD" >"$GIT_DIR/BISECT_TERMS"
+}
+
+check_and_set_terms () {
+	cmd="$1"
+	case "$cmd" in
+	skip|start|terms) ;;
+	*)
+		if test -s "$GIT_DIR/BISECT_TERMS" && test "$cmd" != "$TERM_BAD" && test "$cmd" != "$TERM_GOOD"
+		then
+			die "$(eval_gettext "Invalid command: you're currently in a \$TERM_BAD/\$TERM_GOOD bisect.")"
+		fi
+		case "$cmd" in
+		bad|good)
+			if ! test -s "$GIT_DIR/BISECT_TERMS"
+			then
+				write_terms bad good
+			fi
+			;;
+		esac ;;
+	esac
+}
+
+bisect_voc () {
+	case "$1" in
+	bad) echo "bad" ;;
+	good) echo "good" ;;
+	esac
+}
+
 case "$#" in
 0)
 	usage ;;
 *)
 	cmd="$1"
+	get_terms
 	shift
 	case "$cmd" in
 	help)
 		git bisect -h ;;
 	start)
 		bisect_start "$@" ;;
-	bad|good)
+	bad|good|"$TERM_BAD"|"$TERM_GOOD")
 		bisect_state "$cmd" "$@" ;;
 	skip)
 		bisect_skip "$@" ;;
diff --git a/revision.c b/revision.c
index cf60c5d817..5350139599 100644
--- a/revision.c
+++ b/revision.c
@@ -18,9 +18,13 @@
 #include "commit-slab.h"
 #include "dir.h"
 #include "cache-tree.h"
+#include "bisect.h"
 
 volatile show_early_output_fn_t show_early_output;
 
+static const char *term_bad;
+static const char *term_good;
+
 char *path_name(const struct name_path *path, const char *name)
 {
 	const struct name_path *p;
@@ -2076,14 +2080,23 @@ void parse_revision_opt(struct rev_info *revs, struct parse_opt_ctx_t *ctx,
 	ctx->argc -= n;
 }
 
+static int for_each_bisect_ref(const char *submodule, each_ref_fn fn, void *cb_data, const char *term) {
+	struct strbuf bisect_refs = STRBUF_INIT;
+	int status;
+	strbuf_addf(&bisect_refs, "refs/bisect/%s", term);
+	status = for_each_ref_in_submodule(submodule, bisect_refs.buf, fn, cb_data);
+	strbuf_release(&bisect_refs);
+	return status;
+}
+
 static int for_each_bad_bisect_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-	return for_each_ref_in_submodule(submodule, "refs/bisect/bad", fn, cb_data);
+	return for_each_bisect_ref(submodule, fn, cb_data, term_bad);
 }
 
 static int for_each_good_bisect_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 {
-	return for_each_ref_in_submodule(submodule, "refs/bisect/good", fn, cb_data);
+	return for_each_bisect_ref(submodule, fn, cb_data, term_good);
 }
 
 static int handle_revision_pseudo_opt(const char *submodule,
@@ -2112,6 +2125,7 @@ static int handle_revision_pseudo_opt(const char *submodule,
 		handle_refs(submodule, revs, *flags, for_each_branch_ref_submodule);
 		clear_ref_exclusion(&revs->ref_excludes);
 	} else if (!strcmp(arg, "--bisect")) {
+		read_bisect_terms(&term_bad, &term_good);
 		handle_refs(submodule, revs, *flags, for_each_bad_bisect_ref);
 		handle_refs(submodule, revs, *flags ^ (UNINTERESTING | BOTTOM), for_each_good_bisect_ref);
 		revs->bisect = 1;
diff --git a/t/t6030-bisect-porcelain.sh b/t/t6030-bisect-porcelain.sh
index 06b4868109..9e2c203747 100755
--- a/t/t6030-bisect-porcelain.sh
+++ b/t/t6030-bisect-porcelain.sh
@@ -362,7 +362,7 @@ test_expect_success 'bisect starting with a detached HEAD' '
 test_expect_success 'bisect errors out if bad and good are mistaken' '
 	git bisect reset &&
 	test_must_fail git bisect start $HASH2 $HASH4 2> rev_list_error &&
-	grep "mistake good and bad" rev_list_error &&
+	grep "mistook good and bad" rev_list_error &&
 	git bisect reset
 '