Merge branch 'em/checkout-orphan'

* em/checkout-orphan:
  log_ref_setup: don't return stack-allocated array
  bash completion: add --orphan to 'git checkout'
  t3200: test -l with core.logAllRefUpdates options
  checkout --orphan: respect -l option always
  refs: split log_ref_write logic into log_ref_setup
  Documentation: alter checkout --orphan description

Documentation/git-checkout.txt

@@ -91,22 +91,29 @@ explicitly give a name with '-b' in such a case.
 	details.
 
 --orphan::
-	Create a new branch named <new_branch>, unparented to any other
-	branch.  The new branch you switch to does not have any commit
-	and after the first one it will become the root of a new history
-	completely unconnected from all the other branches.
+	Create a new 'orphan' branch, named <new_branch>, started from
+	<start_point> and switch to it.  The first commit made on this
+	new branch will have no parents and it will be the root of a new
+	history totally disconnected from all the other branches and
+	commits.
 +
-When you use "--orphan", the index and the working tree are kept intact.
-This allows you to start a new history that records set of paths similar
-to that of the start-point commit, which is useful when you want to keep
-different branches for different audiences you are working to like when
-you have an open source and commercial versions of a software, for example.
+The index and the working tree are adjusted as if you had previously run
+"git checkout <start_point>".  This allows you to start a new history
+that records a set of paths similar to <start_point> by easily running
+"git commit -a" to make the root commit.
 +
-If you want to start a disconnected history that records set of paths
-totally different from the original branch, you may want to first clear
-the index and the working tree, by running "git rm -rf ." from the
-top-level of the working tree, before preparing your files (by copying
-from elsewhere, extracting a tarball, etc.) in the working tree.
+This can be useful when you want to publish the tree from a commit
+without exposing its full history. You might want to do this to publish
+an open source branch of a project whose current tree is "clean", but
+whose full history contains proprietary or otherwise encumbered bits of
+code.
++
+If you want to start a disconnected history that records a set of paths
+that is totally different from the one of <start_point>, then you should
+clear the index and the working tree right after creating the orphan
+branch by running "git rm -rf ." from the top level of the working tree.
+Afterwards you will be ready to prepare your new files, repopulating the
+working tree, by copying them from elsewhere, extracting a tarball, etc.
 
 -m::
 --merge::

builtin/checkout.c

@@ -493,7 +493,24 @@ static void update_refs_for_switch(struct checkout_opts *opts,
 	struct strbuf msg = STRBUF_INIT;
 	const char *old_desc;
 	if (opts->new_branch) {
-		if (!opts->new_orphan_branch)
+		if (opts->new_orphan_branch) {
+			if (opts->new_branch_log && !log_all_ref_updates) {
+				int temp;
+				char log_file[PATH_MAX];
+				char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
+
+				temp = log_all_ref_updates;
+				log_all_ref_updates = 1;
+				if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
+					fprintf(stderr, "Can not do reflog for '%s'\n",
+					    opts->new_orphan_branch);
+					log_all_ref_updates = temp;
+					return;
+				}
+				log_all_ref_updates = temp;
+			}
+		}
+		else
 			create_branch(old->name, opts->new_branch, new->name, 0,
 				      opts->new_branch_log, opts->track);
 		new->name = opts->new_branch;
@@ -517,6 +534,14 @@ static void update_refs_for_switch(struct checkout_opts *opts,
 					opts->new_branch ? " a new" : "",
 					new->name);
 		}
+		if (old->path && old->name) {
+			char log_file[PATH_MAX], ref_file[PATH_MAX];
+
+			git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
+			git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
+			if (!file_exists(ref_file) && file_exists(log_file))
+				remove_path(log_file);
+		}
 	} else if (strcmp(new->name, "HEAD")) {
 		update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 			   REF_NODEREF, DIE_ON_ERR);
@@ -684,8 +709,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	if (opts.new_orphan_branch) {
 		if (opts.new_branch)
 			die("--orphan and -b are mutually exclusive");
-		if (opts.track > 0 || opts.new_branch_log)
-			die("--orphan cannot be used with -t or -l");
+		if (opts.track > 0)
+			die("--orphan cannot be used with -t");
 		opts.new_branch = opts.new_orphan_branch;
 	}
 

contrib/completion/git-completion.bash

@@ -842,7 +842,7 @@ _git_checkout ()
 	--*)
 		__gitcomp "
 			--quiet --ours --theirs --track --no-track --merge
-			--conflict= --patch
+			--conflict= --orphan --patch
 			"
 		;;
 	*)

refs.c

@@ -1258,52 +1258,65 @@ static int copy_msg(char *buf, const char *msg)
 	return cp - buf;
 }
 
-static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
-			 const unsigned char *new_sha1, const char *msg)
+int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
 {
-	int logfd, written, oflags = O_APPEND | O_WRONLY;
-	unsigned maxlen, len;
-	int msglen;
-	char log_file[PATH_MAX];
-	char *logrec;
-	const char *committer;
-
-	if (log_all_ref_updates < 0)
-		log_all_ref_updates = !is_bare_repository();
-
-	git_snpath(log_file, sizeof(log_file), "logs/%s", ref_name);
+	int logfd, oflags = O_APPEND | O_WRONLY;
 
+	git_snpath(logfile, bufsize, "logs/%s", ref_name);
 	if (log_all_ref_updates &&
 	    (!prefixcmp(ref_name, "refs/heads/") ||
 	     !prefixcmp(ref_name, "refs/remotes/") ||
 	     !prefixcmp(ref_name, "refs/notes/") ||
 	     !strcmp(ref_name, "HEAD"))) {
-		if (safe_create_leading_directories(log_file) < 0)
+		if (safe_create_leading_directories(logfile) < 0)
 			return error("unable to create directory for %s",
-				     log_file);
+				     logfile);
 		oflags |= O_CREAT;
 	}
 
-	logfd = open(log_file, oflags, 0666);
+	logfd = open(logfile, oflags, 0666);
 	if (logfd < 0) {
 		if (!(oflags & O_CREAT) && errno == ENOENT)
 			return 0;
 
 		if ((oflags & O_CREAT) && errno == EISDIR) {
-			if (remove_empty_directories(log_file)) {
+			if (remove_empty_directories(logfile)) {
 				return error("There are still logs under '%s'",
-					     log_file);
+					     logfile);
 			}
-			logfd = open(log_file, oflags, 0666);
+			logfd = open(logfile, oflags, 0666);
 		}
 
 		if (logfd < 0)
 			return error("Unable to append to %s: %s",
-				     log_file, strerror(errno));
+				     logfile, strerror(errno));
 	}
 
-	adjust_shared_perm(log_file);
+	adjust_shared_perm(logfile);
+	close(logfd);
+	return 0;
+}
 
+static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
+			 const unsigned char *new_sha1, const char *msg)
+{
+	int logfd, result, written, oflags = O_APPEND | O_WRONLY;
+	unsigned maxlen, len;
+	int msglen;
+	char log_file[PATH_MAX];
+	char *logrec;
+	const char *committer;
+
+	if (log_all_ref_updates < 0)
+		log_all_ref_updates = !is_bare_repository();
+
+	result = log_ref_setup(ref_name, log_file, sizeof(log_file));
+	if (result)
+		return result;
+
+	logfd = open(log_file, oflags);
+	if (logfd < 0)
+		return 0;
 	msglen = msg ? strlen(msg) : 0;
 	committer = git_committer_info(0);
 	maxlen = strlen(committer) + msglen + 100;

refs.h

@@ -68,6 +68,9 @@ extern void unlock_ref(struct ref_lock *lock);
 /** Writes sha1 into the ref specified by the lock. **/
 extern int write_ref_sha1(struct ref_lock *lock, const unsigned char *sha1, const char *msg);
 
+/** Setup reflog before using. **/
+int log_ref_setup(const char *ref_name, char *logfile, int bufsize);
+
 /** Reads log for the value of ref during at_time. **/
 extern int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1, char **msg, unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt);
 

t/t2017-checkout-orphan.sh

@@ -49,6 +49,62 @@ test_expect_success '--orphan must be rejected with -b' '
 	test refs/heads/master = "$(git symbolic-ref HEAD)"
 '
 
+test_expect_success '--orphan must be rejected with -t' '
+	git checkout master &&
+	test_must_fail git checkout --orphan new -t master &&
+	test refs/heads/master = "$(git symbolic-ref HEAD)"
+'
+
+test_expect_success '--orphan ignores branch.autosetupmerge' '
+	git checkout master &&
+	git config branch.autosetupmerge always &&
+	git checkout --orphan gamma &&
+	test -z "$(git config branch.gamma.merge)" &&
+	test refs/heads/gamma = "$(git symbolic-ref HEAD)" &&
+	test_must_fail git rev-parse --verify HEAD^
+'
+
+test_expect_success '--orphan makes reflog by default' '
+	git checkout master &&
+	git config --unset core.logAllRefUpdates &&
+	git checkout --orphan delta &&
+	! test -f .git/logs/refs/heads/delta &&
+	test_must_fail PAGER= git reflog show delta &&
+	git commit -m Delta &&
+	test -f .git/logs/refs/heads/delta &&
+	PAGER= git reflog show delta
+'
+
+test_expect_success '--orphan does not make reflog when core.logAllRefUpdates = false' '
+	git checkout master &&
+	git config core.logAllRefUpdates false &&
+	git checkout --orphan epsilon &&
+	! test -f .git/logs/refs/heads/epsilon &&
+	test_must_fail PAGER= git reflog show epsilon &&
+	git commit -m Epsilon &&
+	! test -f .git/logs/refs/heads/epsilon &&
+	test_must_fail PAGER= git reflog show epsilon
+'
+
+test_expect_success '--orphan with -l makes reflog when core.logAllRefUpdates = false' '
+	git checkout master &&
+	git checkout -l --orphan zeta &&
+	test -f .git/logs/refs/heads/zeta &&
+	test_must_fail PAGER= git reflog show zeta &&
+	git commit -m Zeta &&
+	PAGER= git reflog show zeta
+'
+
+test_expect_success 'giving up --orphan not committed when -l and core.logAllRefUpdates = false deletes reflog' '
+	git checkout master &&
+	git checkout -l --orphan eta &&
+	test -f .git/logs/refs/heads/eta &&
+	test_must_fail PAGER= git reflog show eta &&
+	git checkout master &&
+	! test -f .git/logs/refs/heads/eta &&
+	test_must_fail PAGER= git reflog show eta
+'
+
 test_expect_success '--orphan is rejected with an existing name' '
 	git checkout master &&
 	test_must_fail git checkout --orphan master &&
@@ -60,31 +116,11 @@ test_expect_success '--orphan refuses to switch if a merge is needed' '
 	git reset --hard &&
 	echo local >>"$TEST_FILE" &&
 	cat "$TEST_FILE" >"$TEST_FILE.saved" &&
-	test_must_fail git checkout --orphan gamma master^ &&
+	test_must_fail git checkout --orphan new master^ &&
 	test refs/heads/master = "$(git symbolic-ref HEAD)" &&
 	test_cmp "$TEST_FILE" "$TEST_FILE.saved" &&
 	git diff-index --quiet --cached HEAD &&
 	git reset --hard
 '
 
-test_expect_success '--orphan does not mix well with -t' '
-	git checkout master &&
-	test_must_fail git checkout -t master --orphan gamma &&
-	test refs/heads/master = "$(git symbolic-ref HEAD)"
-'
-
-test_expect_success '--orphan ignores branch.autosetupmerge' '
-	git checkout -f master &&
-	git config branch.autosetupmerge always &&
-	git checkout --orphan delta &&
-	test -z "$(git config branch.delta.merge)" &&
-	test refs/heads/delta = "$(git symbolic-ref HEAD)" &&
-	test_must_fail git rev-parse --verify HEAD^
-'
-
-test_expect_success '--orphan does not mix well with -l' '
-	git checkout -f master &&
-	test_must_fail git checkout -l --orphan gamma
-'
-
 test_done

t/t3200-branch.sh

@@ -224,6 +224,30 @@ test_expect_success \
 	 test -f .git/logs/refs/heads/g/h/i &&
 	 diff expect .git/logs/refs/heads/g/h/i'
 
+test_expect_success 'checkout -b makes reflog by default' '
+	git checkout master &&
+	git config --unset core.logAllRefUpdates &&
+	git checkout -b alpha &&
+	test -f .git/logs/refs/heads/alpha &&
+	PAGER= git reflog show alpha
+'
+
+test_expect_success 'checkout -b does not make reflog when core.logAllRefUpdates = false' '
+	git checkout master &&
+	git config core.logAllRefUpdates false &&
+	git checkout -b beta &&
+	! test -f .git/logs/refs/heads/beta &&
+	test_must_fail PAGER= git reflog show beta
+'
+
+test_expect_success 'checkout -b with -l makes reflog when core.logAllRefUpdates = false' '
+	git checkout master &&
+	git checkout -lb gamma &&
+	git config --unset core.logAllRefUpdates &&
+	test -f .git/logs/refs/heads/gamma &&
+	PAGER= git reflog show gamma
+'
+
 test_expect_success 'avoid ambiguous track' '
 	git config branch.autosetupmerge true &&
 	git config remote.ambi1.url lalala &&