From 5c3146487459b80898b50686740bb273b2c2b022 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:38 -0400
Subject: Documentation/git-checkout: fix incorrect worktree prune command

This was missed when "git prune --worktrees" became "git worktree prune".

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-checkout.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 72def5b68..ce223e69a 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -444,7 +444,7 @@ When you are done with a linked working tree you can simply delete it.
 The working tree's entry in the repository's $GIT_DIR/worktrees
 directory will eventually be removed automatically (see
 `gc.pruneworktreesexpire` in linkgit::git-config[1]), or you can run
-`git prune --worktrees` in the main or any linked working tree to
+`git worktree prune` in the main or any linked working tree to
 clean up any stale entries in $GIT_DIR/worktrees.
 
 If you move a linked working directory to another file system, or
-- 
cgit v1.2.1


From 4f09825e58ce1da7af8cc96bff5a6b118790fffa Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:39 -0400
Subject: Documentation/git-worktree: associate options with commands

git-worktree options affect some worktree commands but not others, but
this is not necessarily obvious from the option descriptions. Make this
clear by indicating explicitly which commands are affected by which
options.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 41103e548..1ac1217b0 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -28,15 +28,15 @@ OPTIONS
 
 -n::
 --dry-run::
-	Do not remove anything; just report what it would
+	With `prune`, do not remove anything; just report what it would
 	remove.
 
 -v::
 --verbose::
-	Report all removals.
+	With `prune`, report all removals.
 
 --expire <time>::
-	Only expire unused worktrees older than <time>.
+	With `prune`, only expire unused worktrees older than <time>.
 
 SEE ALSO
 --------
-- 
cgit v1.2.1


From 93a36493e2c9478c496328118dc52f6b270c7408 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:40 -0400
Subject: Documentation: move linked worktree description from checkout to
 worktree

Now that the git-worktree command exists, its documentation page is the
natural place for the linked worktree description to reside. Relocate
the "MULTIPLE WORKING TREES" description verbatim from git-checkout.txt
to git-worktree.txt.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-checkout.txt | 69 ++----------------------------------------
 Documentation/git-worktree.txt | 62 +++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 67 deletions(-)

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index ce223e69a..77b7141f0 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -229,8 +229,8 @@ section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
 	Check out a branch in a separate working directory at
 	`<path>`. A new working directory is linked to the current
 	repository, sharing everything except working directory
-	specific files such as HEAD, index... See "MULTIPLE WORKING
-	TREES" section for more information.
+	specific files such as HEAD, index, etc. See
+	linkgit:git-worktree[1] for a description of linked worktrees.
 
 --ignore-other-worktrees::
 	`git checkout` refuses when the wanted ref is already checked
@@ -401,71 +401,6 @@ $ git reflog -2 HEAD # or
 $ git log -g -2 HEAD
 ------------
 
-MULTIPLE WORKING TREES
-----------------------
-
-A git repository can support multiple working trees, allowing you to check
-out more than one branch at a time.  With `git checkout --to` a new working
-tree is associated with the repository.  This new working tree is called a
-"linked working tree" as opposed to the "main working tree" prepared by "git
-init" or "git clone".  A repository has one main working tree (if it's not a
-bare repository) and zero or more linked working trees.
-
-Each linked working tree has a private sub-directory in the repository's
-$GIT_DIR/worktrees directory.  The private sub-directory's name is usually
-the base name of the linked working tree's path, possibly appended with a
-number to make it unique.  For example, when `$GIT_DIR=/path/main/.git` the
-command `git checkout --to /path/other/test-next next` creates the linked
-working tree in `/path/other/test-next` and also creates a
-`$GIT_DIR/worktrees/test-next` directory (or `$GIT_DIR/worktrees/test-next1`
-if `test-next` is already taken).
-
-Within a linked working tree, $GIT_DIR is set to point to this private
-directory (e.g. `/path/main/.git/worktrees/test-next` in the example) and
-$GIT_COMMON_DIR is set to point back to the main working tree's $GIT_DIR
-(e.g. `/path/main/.git`). These settings are made in a `.git` file located at
-the top directory of the linked working tree.
-
-Path resolution via `git rev-parse --git-path` uses either
-$GIT_DIR or $GIT_COMMON_DIR depending on the path. For example, in the
-linked working tree `git rev-parse --git-path HEAD` returns
-`/path/main/.git/worktrees/test-next/HEAD` (not
-`/path/other/test-next/.git/HEAD` or `/path/main/.git/HEAD`) while `git
-rev-parse --git-path refs/heads/master` uses
-$GIT_COMMON_DIR and returns `/path/main/.git/refs/heads/master`,
-since refs are shared across all working trees.
-
-See linkgit:gitrepository-layout[5] for more information. The rule of
-thumb is do not make any assumption about whether a path belongs to
-$GIT_DIR or $GIT_COMMON_DIR when you need to directly access something
-inside $GIT_DIR. Use `git rev-parse --git-path` to get the final path.
-
-When you are done with a linked working tree you can simply delete it.
-The working tree's entry in the repository's $GIT_DIR/worktrees
-directory will eventually be removed automatically (see
-`gc.pruneworktreesexpire` in linkgit::git-config[1]), or you can run
-`git worktree prune` in the main or any linked working tree to
-clean up any stale entries in $GIT_DIR/worktrees.
-
-If you move a linked working directory to another file system, or
-within a file system that does not support hard links, you need to run
-at least one git command inside the linked working directory
-(e.g. `git status`) in order to update its entry in $GIT_DIR/worktrees
-so that it does not get automatically removed.
-
-To prevent a $GIT_DIR/worktrees entry from from being pruned (which
-can be useful in some situations, such as when the
-entry's working tree is stored on a portable device), add a file named
-'locked' to the entry's directory. The file contains the reason in
-plain text. For example, if a linked working tree's `.git` file points
-to `/path/main/.git/worktrees/test-next` then a file named
-`/path/main/.git/worktrees/test-next/locked` will prevent the
-`test-next` entry from being pruned.  See
-linkgit:gitrepository-layout[5] for details.
-
-Multiple checkout support for submodules is incomplete. It is NOT
-recommended to make multiple checkouts of a superproject.
-
 EXAMPLES
 --------
 
diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 1ac1217b0..3d288967f 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -17,6 +17,68 @@ DESCRIPTION
 Manage multiple worktrees attached to the same repository. These are
 created by the command `git checkout --to`.
 
+A git repository can support multiple working trees, allowing you to check
+out more than one branch at a time.  With `git checkout --to` a new working
+tree is associated with the repository.  This new working tree is called a
+"linked working tree" as opposed to the "main working tree" prepared by "git
+init" or "git clone".  A repository has one main working tree (if it's not a
+bare repository) and zero or more linked working trees.
+
+Each linked working tree has a private sub-directory in the repository's
+$GIT_DIR/worktrees directory.  The private sub-directory's name is usually
+the base name of the linked working tree's path, possibly appended with a
+number to make it unique.  For example, when `$GIT_DIR=/path/main/.git` the
+command `git checkout --to /path/other/test-next next` creates the linked
+working tree in `/path/other/test-next` and also creates a
+`$GIT_DIR/worktrees/test-next` directory (or `$GIT_DIR/worktrees/test-next1`
+if `test-next` is already taken).
+
+Within a linked working tree, $GIT_DIR is set to point to this private
+directory (e.g. `/path/main/.git/worktrees/test-next` in the example) and
+$GIT_COMMON_DIR is set to point back to the main working tree's $GIT_DIR
+(e.g. `/path/main/.git`). These settings are made in a `.git` file located at
+the top directory of the linked working tree.
+
+Path resolution via `git rev-parse --git-path` uses either
+$GIT_DIR or $GIT_COMMON_DIR depending on the path. For example, in the
+linked working tree `git rev-parse --git-path HEAD` returns
+`/path/main/.git/worktrees/test-next/HEAD` (not
+`/path/other/test-next/.git/HEAD` or `/path/main/.git/HEAD`) while `git
+rev-parse --git-path refs/heads/master` uses
+$GIT_COMMON_DIR and returns `/path/main/.git/refs/heads/master`,
+since refs are shared across all working trees.
+
+See linkgit:gitrepository-layout[5] for more information. The rule of
+thumb is do not make any assumption about whether a path belongs to
+$GIT_DIR or $GIT_COMMON_DIR when you need to directly access something
+inside $GIT_DIR. Use `git rev-parse --git-path` to get the final path.
+
+When you are done with a linked working tree you can simply delete it.
+The working tree's entry in the repository's $GIT_DIR/worktrees
+directory will eventually be removed automatically (see
+`gc.pruneworktreesexpire` in linkgit::git-config[1]), or you can run
+`git worktree prune` in the main or any linked working tree to
+clean up any stale entries in $GIT_DIR/worktrees.
+
+If you move a linked working directory to another file system, or
+within a file system that does not support hard links, you need to run
+at least one git command inside the linked working directory
+(e.g. `git status`) in order to update its entry in $GIT_DIR/worktrees
+so that it does not get automatically removed.
+
+To prevent a $GIT_DIR/worktrees entry from from being pruned (which
+can be useful in some situations, such as when the
+entry's working tree is stored on a portable device), add a file named
+'locked' to the entry's directory. The file contains the reason in
+plain text. For example, if a linked working tree's `.git` file points
+to `/path/main/.git/worktrees/test-next` then a file named
+`/path/main/.git/worktrees/test-next/locked` will prevent the
+`test-next` entry from being pruned.  See
+linkgit:gitrepository-layout[5] for details.
+
+Multiple checkout support for submodules is incomplete. It is NOT
+recommended to make multiple checkouts of a superproject.
+
 COMMANDS
 --------
 prune::
-- 
cgit v1.2.1


From 6d3824cf92c14d81ffb2ecaa76e35a811b7f596f Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:41 -0400
Subject: Documentation/git-worktree: add BUGS section

Relocate submodule warning to BUGS and enumerate missing commands.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 3d288967f..bf6a1e229 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -76,9 +76,6 @@ to `/path/main/.git/worktrees/test-next` then a file named
 `test-next` entry from being pruned.  See
 linkgit:gitrepository-layout[5] for details.
 
-Multiple checkout support for submodules is incomplete. It is NOT
-recommended to make multiple checkouts of a superproject.
-
 COMMANDS
 --------
 prune::
@@ -100,6 +97,22 @@ OPTIONS
 --expire <time>::
 	With `prune`, only expire unused worktrees older than <time>.
 
+BUGS
+----
+Multiple checkout support for submodules is incomplete. It is NOT
+recommended to make multiple checkouts of a superproject.
+
+git-worktree could provide more automation for tasks currently
+performed manually or via other commands, such as:
+
+- `add` to create a new linked worktree
+- `remove` to remove a linked worktree and its administrative files (and
+  warn if the worktree is dirty)
+- `mv` to move or rename a worktree and update its administrative files
+- `list` to list linked worktrees
+- `lock` to prevent automatic pruning of administrative files (for instance,
+  for a worktree on a portable device)
+
 SEE ALSO
 --------
 
-- 
cgit v1.2.1


From af189b4cbec7f6ff4687c8ca78b2455c1f28923c Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:42 -0400
Subject: Documentation/git-worktree: split technical info from general
 description

The DESCRIPTION section should provide a high-level overview of linked
worktree functionality to bring users up to speed quickly, without
overloading them with low-level details, so relocate the technical
information to a new DETAILS section.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 70 ++++++++++++++++++++++--------------------
 1 file changed, 36 insertions(+), 34 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index bf6a1e229..2954dc6dc 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -24,47 +24,18 @@ tree is associated with the repository.  This new working tree is called a
 init" or "git clone".  A repository has one main working tree (if it's not a
 bare repository) and zero or more linked working trees.
 
-Each linked working tree has a private sub-directory in the repository's
-$GIT_DIR/worktrees directory.  The private sub-directory's name is usually
-the base name of the linked working tree's path, possibly appended with a
-number to make it unique.  For example, when `$GIT_DIR=/path/main/.git` the
-command `git checkout --to /path/other/test-next next` creates the linked
-working tree in `/path/other/test-next` and also creates a
-`$GIT_DIR/worktrees/test-next` directory (or `$GIT_DIR/worktrees/test-next1`
-if `test-next` is already taken).
-
-Within a linked working tree, $GIT_DIR is set to point to this private
-directory (e.g. `/path/main/.git/worktrees/test-next` in the example) and
-$GIT_COMMON_DIR is set to point back to the main working tree's $GIT_DIR
-(e.g. `/path/main/.git`). These settings are made in a `.git` file located at
-the top directory of the linked working tree.
-
-Path resolution via `git rev-parse --git-path` uses either
-$GIT_DIR or $GIT_COMMON_DIR depending on the path. For example, in the
-linked working tree `git rev-parse --git-path HEAD` returns
-`/path/main/.git/worktrees/test-next/HEAD` (not
-`/path/other/test-next/.git/HEAD` or `/path/main/.git/HEAD`) while `git
-rev-parse --git-path refs/heads/master` uses
-$GIT_COMMON_DIR and returns `/path/main/.git/refs/heads/master`,
-since refs are shared across all working trees.
-
-See linkgit:gitrepository-layout[5] for more information. The rule of
-thumb is do not make any assumption about whether a path belongs to
-$GIT_DIR or $GIT_COMMON_DIR when you need to directly access something
-inside $GIT_DIR. Use `git rev-parse --git-path` to get the final path.
-
 When you are done with a linked working tree you can simply delete it.
-The working tree's entry in the repository's $GIT_DIR/worktrees
-directory will eventually be removed automatically (see
+The working tree's administrative files in the repository (see
+"DETAILS" below) will eventually be removed automatically (see
 `gc.pruneworktreesexpire` in linkgit::git-config[1]), or you can run
 `git worktree prune` in the main or any linked working tree to
-clean up any stale entries in $GIT_DIR/worktrees.
+clean up any stale administrative files.
 
 If you move a linked working directory to another file system, or
 within a file system that does not support hard links, you need to run
 at least one git command inside the linked working directory
-(e.g. `git status`) in order to update its entry in $GIT_DIR/worktrees
-so that it does not get automatically removed.
+(e.g. `git status`) in order to update its administrative files in the
+repository so that they do not get automatically pruned.
 
 To prevent a $GIT_DIR/worktrees entry from from being pruned (which
 can be useful in some situations, such as when the
@@ -97,6 +68,37 @@ OPTIONS
 --expire <time>::
 	With `prune`, only expire unused worktrees older than <time>.
 
+DETAILS
+-------
+Each linked working tree has a private sub-directory in the repository's
+$GIT_DIR/worktrees directory.  The private sub-directory's name is usually
+the base name of the linked working tree's path, possibly appended with a
+number to make it unique.  For example, when `$GIT_DIR=/path/main/.git` the
+command `git checkout --to /path/other/test-next next` creates the linked
+working tree in `/path/other/test-next` and also creates a
+`$GIT_DIR/worktrees/test-next` directory (or `$GIT_DIR/worktrees/test-next1`
+if `test-next` is already taken).
+
+Within a linked working tree, $GIT_DIR is set to point to this private
+directory (e.g. `/path/main/.git/worktrees/test-next` in the example) and
+$GIT_COMMON_DIR is set to point back to the main working tree's $GIT_DIR
+(e.g. `/path/main/.git`). These settings are made in a `.git` file located at
+the top directory of the linked working tree.
+
+Path resolution via `git rev-parse --git-path` uses either
+$GIT_DIR or $GIT_COMMON_DIR depending on the path. For example, in the
+linked working tree `git rev-parse --git-path HEAD` returns
+`/path/main/.git/worktrees/test-next/HEAD` (not
+`/path/other/test-next/.git/HEAD` or `/path/main/.git/HEAD`) while `git
+rev-parse --git-path refs/heads/master` uses
+$GIT_COMMON_DIR and returns `/path/main/.git/refs/heads/master`,
+since refs are shared across all working trees.
+
+See linkgit:gitrepository-layout[5] for more information. The rule of
+thumb is do not make any assumption about whether a path belongs to
+$GIT_DIR or $GIT_COMMON_DIR when you need to directly access something
+inside $GIT_DIR. Use `git rev-parse --git-path` to get the final path.
+
 BUGS
 ----
 Multiple checkout support for submodules is incomplete. It is NOT
-- 
cgit v1.2.1


From a8ba5dd7b18ed3a3276ee23ab66569dbddc50913 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:43 -0400
Subject: Documentation/git-worktree: add high-level 'lock' overview

Due to the (current) absence of a "git worktree lock" command, locking
a worktree's administrative files to prevent automatic pruning is a
manual task, necessarily requiring low-level understanding of linked
worktree functionality. However, this level of detail does not belong
in the high-level DESCRIPTION section, so add a generalized discussion
of locking to DESCRIPTION and move the technical information to DETAILS.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 2954dc6dc..0385e9a6d 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -37,15 +37,11 @@ at least one git command inside the linked working directory
 (e.g. `git status`) in order to update its administrative files in the
 repository so that they do not get automatically pruned.
 
-To prevent a $GIT_DIR/worktrees entry from from being pruned (which
-can be useful in some situations, such as when the
-entry's working tree is stored on a portable device), add a file named
-'locked' to the entry's directory. The file contains the reason in
-plain text. For example, if a linked working tree's `.git` file points
-to `/path/main/.git/worktrees/test-next` then a file named
-`/path/main/.git/worktrees/test-next/locked` will prevent the
-`test-next` entry from being pruned.  See
-linkgit:gitrepository-layout[5] for details.
+If a linked working tree is stored on a portable device or network share
+which is not always mounted, you can prevent its administrative files from
+being pruned by creating a file named 'lock' alongside the other
+administrative files, optionally containing a plain text reason that
+pruning should be suppressed. See section "DETAILS" for more information.
 
 COMMANDS
 --------
@@ -99,6 +95,16 @@ thumb is do not make any assumption about whether a path belongs to
 $GIT_DIR or $GIT_COMMON_DIR when you need to directly access something
 inside $GIT_DIR. Use `git rev-parse --git-path` to get the final path.
 
+To prevent a $GIT_DIR/worktrees entry from from being pruned (which
+can be useful in some situations, such as when the
+entry's working tree is stored on a portable device), add a file named
+'locked' to the entry's directory. The file contains the reason in
+plain text. For example, if a linked working tree's `.git` file points
+to `/path/main/.git/worktrees/test-next` then a file named
+`/path/main/.git/worktrees/test-next/locked` will prevent the
+`test-next` entry from being pruned.  See
+linkgit:gitrepository-layout[5] for details.
+
 BUGS
 ----
 Multiple checkout support for submodules is incomplete. It is NOT
-- 
cgit v1.2.1


From 96454597562dade701fbfee19891482a97456138 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:44 -0400
Subject: Documentation/git-worktree: add EXAMPLES section

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 0385e9a6d..6afff1ed0 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -105,6 +105,28 @@ to `/path/main/.git/worktrees/test-next` then a file named
 `test-next` entry from being pruned.  See
 linkgit:gitrepository-layout[5] for details.
 
+EXAMPLES
+--------
+You are in the middle of a refactoring session and your boss comes in and
+demands that you fix something immediately. You might typically use
+linkgit:git-stash[1] to store your changes away temporarily, however, your
+worktree is in such a state of disarray (with new, moved, and removed files,
+and other bits and pieces strewn around) that you don't want to risk
+disturbing any of it. Instead, you create a temporary linked worktree to
+make the emergency fix, remove it when done, and then resume your earlier
+refactoring session.
+
+------------
+$ git branch emergency-fix master
+$ git checkout --to ../temp emergency-fix
+$ pushd ../temp
+# ... hack hack hack ...
+$ git commit -a -m 'emergency fix for boss'
+$ popd
+$ rm -rf ../temp
+$ git worktree prune
+------------
+
 BUGS
 ----
 Multiple checkout support for submodules is incomplete. It is NOT
-- 
cgit v1.2.1


From c990a4c11dd7bb671da1b30e14568ad986621488 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:45 -0400
Subject: checkout: fix bug with --to and relative HEAD

Given "git checkout --to <path> HEAD~1", the new worktree's HEAD should
begin life at the current branch's HEAD~1, however, it actually ends up
at HEAD~2. This happens because:

    1. git-checkout resolves HEAD~1

    2. to satisfy is_git_directory(), prepare_linked_worktree() creates
       a HEAD for the new worktree with the value of the resolved HEAD~1

    3. git-checkout re-invokes itself with the same arguments within the
       new worktree to populate the worktree

    4. the sub git-checkout resolves HEAD~1 relative to its own HEAD,
       which is the resolved HEAD~1 from the original invocation,
       resulting unexpectedly and incorrectly in HEAD~2 (relative to the
       original)

Fix this by unconditionally assigning the current worktree's HEAD as the
value of the new worktree's HEAD.

As a side-effect, this change also eliminates a dependence within
prepare_linked_checkout() upon 'struct branch_info'. The plan is to
eventually relocate "git checkout --to" functionality to "git worktree
add", and worktree.c won't have knowledge of 'struct branch_info', so
removal of this dependency is a step toward that goal.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/checkout.c     | 16 ++++++++++++----
 t/t2025-checkout-to.sh | 10 ++++++++++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 2079aa417..5ada22a39 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -863,6 +863,7 @@ static int prepare_linked_checkout(const struct checkout_opts *opts,
 	struct stat st;
 	struct child_process cp;
 	int counter = 0, len, ret;
+	unsigned char rev[20];
 
 	if (!new->commit)
 		die(_("no branch specified"));
@@ -920,13 +921,20 @@ static int prepare_linked_checkout(const struct checkout_opts *opts,
 		   real_path(get_git_common_dir()), name);
 	/*
 	 * This is to keep resolve_ref() happy. We need a valid HEAD
-	 * or is_git_directory() will reject the directory. Any valid
-	 * value would do because this value will be ignored and
-	 * replaced at the next (real) checkout.
+	 * or is_git_directory() will reject the directory. Moreover, HEAD
+	 * in the new worktree must resolve to the same value as HEAD in
+	 * the current tree since the command invoked to populate the new
+	 * worktree will be handed the branch/ref specified by the user.
+	 * For instance, if the user asks for the new worktree to be based
+	 * at HEAD~5, then the resolved HEAD~5 in the new worktree must
+	 * match the resolved HEAD~5 in the current tree in order to match
+	 * the user's expectation.
 	 */
+	if (!resolve_ref_unsafe("HEAD", 0, rev, NULL))
+		die(_("unable to resolve HEAD"));
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
-	write_file(sb.buf, 1, "%s\n", sha1_to_hex(new->commit->object.sha1));
+	write_file(sb.buf, 1, "%s\n", sha1_to_hex(rev));
 	strbuf_reset(&sb);
 	strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
 	write_file(sb.buf, 1, "../..\n");
diff --git a/t/t2025-checkout-to.sh b/t/t2025-checkout-to.sh
index a8d93366f..0fd731b4b 100755
--- a/t/t2025-checkout-to.sh
+++ b/t/t2025-checkout-to.sh
@@ -134,4 +134,14 @@ test_expect_success 'checkout with grafts' '
 	test_cmp expected actual
 '
 
+test_expect_success 'checkout --to from relative HEAD' '
+	test_commit a &&
+	test_commit b &&
+	test_commit c &&
+	git rev-parse HEAD~1 >expected &&
+	git checkout --to relhead HEAD~1 &&
+	git -C relhead rev-parse HEAD >actual &&
+	test_cmp expected actual
+'
+
 test_done
-- 
cgit v1.2.1


From 9559ce8368b533862584b2717532e3c25232f1c9 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:46 -0400
Subject: checkout: relocate --to's "no branch specified" check

The plan is to relocate "git checkout --to" functionality to "git
worktree add", however, this check expects a 'struct branch_info' which
git-worktree won't have at hand. It will, however, have access to its
own command-line from which it can pick up the branch name. Therefore,
as a preparatory step, rather than having prepare_linked_checkout()
perform this check, make it the caller's responsibility.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/checkout.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 5ada22a39..162c82226 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -865,8 +865,6 @@ static int prepare_linked_checkout(const struct checkout_opts *opts,
 	int counter = 0, len, ret;
 	unsigned char rev[20];
 
-	if (!new->commit)
-		die(_("no branch specified"));
 	if (file_exists(path) && !is_empty_dir(path))
 		die(_("'%s' already exists"), path);
 
@@ -1303,8 +1301,11 @@ static int checkout_branch(struct checkout_opts *opts,
 		free(head_ref);
 	}
 
-	if (opts->new_worktree)
+	if (opts->new_worktree) {
+		if (!new->commit)
+			die(_("no branch specified"));
 		return prepare_linked_checkout(opts, new);
+	}
 
 	if (!new->commit && opts->new_branch) {
 		unsigned char rev[20];
-- 
cgit v1.2.1


From 3c3e7f5b57f94b8f5fcba5042cf2412625c24d4a Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:47 -0400
Subject: checkout: prepare_linked_checkout: drop now-unused 'new' argument

The only references to 'new' were folded out by the last two patches.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/checkout.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 162c82226..134b6d65f 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -854,8 +854,7 @@ static void remove_junk_on_signal(int signo)
 	raise(signo);
 }
 
-static int prepare_linked_checkout(const struct checkout_opts *opts,
-				   struct branch_info *new)
+static int prepare_linked_checkout(const struct checkout_opts *opts)
 {
 	struct strbuf sb_git = STRBUF_INIT, sb_repo = STRBUF_INIT;
 	struct strbuf sb = STRBUF_INIT;
@@ -1304,7 +1303,7 @@ static int checkout_branch(struct checkout_opts *opts,
 	if (opts->new_worktree) {
 		if (!new->commit)
 			die(_("no branch specified"));
-		return prepare_linked_checkout(opts, new);
+		return prepare_linked_checkout(opts);
 	}
 
 	if (!new->commit && opts->new_branch) {
-- 
cgit v1.2.1


From 338dfd0da4b7fd3ccf0772788d64cbcdf089f486 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:48 -0400
Subject: checkout: make --to unconditionally verbose

prepare_linked_checkout() respects git-checkout's --quiet flag, however,
the plan is to relocate "git checkout --to" functionality to "git
worktree add", and git-worktree does not (yet) have a --quiet flag.
Consequently, make prepare_linked_checkout() unconditionally verbose to
ease eventual code movement to worktree.c.

(A --quiet flag can be added to git-worktree later if there is demand
for it.)

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/checkout.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 134b6d65f..90bb3cdf2 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -936,8 +936,7 @@ static int prepare_linked_checkout(const struct checkout_opts *opts)
 	strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
 	write_file(sb.buf, 1, "../..\n");
 
-	if (!opts->quiet)
-		fprintf_ln(stderr, _("Enter %s (identifier %s)"), path, name);
+	fprintf_ln(stderr, _("Enter %s (identifier %s)"), path, name);
 
 	setenv("GIT_CHECKOUT_NEW_WORKTREE", "1", 1);
 	setenv(GIT_DIR_ENVIRONMENT, sb_git.buf, 1);
-- 
cgit v1.2.1


From bdf0f375b9cf1c272233583a03eddef1772da99e Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:49 -0400
Subject: checkout: drop 'checkout_opts' dependency from
 prepare_linked_checkout

The plan is to relocate "git checkout --to" functionality to "git
worktree add", however, worktree.c won't have access to the 'struct
checkout_opts' passed to prepare_linked_worktree(), which it consults
for the pathname of the new worktree and the argv[] of the command it
should run to populate the new worktree. Facilitate relocation of
prepare_linked_worktree() by instead having it accept the pathname and
argv[] directly, thus eliminating the final references to 'struct
checkout_opts'.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/checkout.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 90bb3cdf2..e4064a84c 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -854,11 +854,11 @@ static void remove_junk_on_signal(int signo)
 	raise(signo);
 }
 
-static int prepare_linked_checkout(const struct checkout_opts *opts)
+static int prepare_linked_checkout(const char *path, const char **child_argv)
 {
 	struct strbuf sb_git = STRBUF_INIT, sb_repo = STRBUF_INIT;
 	struct strbuf sb = STRBUF_INIT;
-	const char *path = opts->new_worktree, *name;
+	const char *name;
 	struct stat st;
 	struct child_process cp;
 	int counter = 0, len, ret;
@@ -943,7 +943,7 @@ static int prepare_linked_checkout(const struct checkout_opts *opts)
 	setenv(GIT_WORK_TREE_ENVIRONMENT, path, 1);
 	memset(&cp, 0, sizeof(cp));
 	cp.git_cmd = 1;
-	cp.argv = opts->saved_argv;
+	cp.argv = child_argv;
 	ret = run_command(&cp);
 	if (!ret) {
 		is_junk = 0;
@@ -1302,7 +1302,8 @@ static int checkout_branch(struct checkout_opts *opts,
 	if (opts->new_worktree) {
 		if (!new->commit)
 			die(_("no branch specified"));
-		return prepare_linked_checkout(opts);
+		return prepare_linked_checkout(opts->new_worktree,
+					       opts->saved_argv);
 	}
 
 	if (!new->commit && opts->new_branch) {
-- 
cgit v1.2.1


From fc56361f58a20f1259e1ba2364424ec27825c37f Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:50 -0400
Subject: worktree: introduce "add" command

The plan is to relocate "git checkout --to" functionality to "git
worktree add". As a first step, introduce a bare-bones git-worktree
"add" command along with documentation. At this stage, "git worktree
add" merely invokes "git checkout --to" behind the scenes, but an
upcoming patch will move the actual functionality
(checkout.c:prepare_linked_checkout() and its helpers) to worktree.c.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 20 ++++++++++----------
 builtin/worktree.c             | 31 +++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 6afff1ed0..def3027c4 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -9,13 +9,13 @@ git-worktree - Manage multiple worktrees
 SYNOPSIS
 --------
 [verse]
+'git worktree add' <path> <branch>
 'git worktree prune' [-n] [-v] [--expire <expire>]
 
 DESCRIPTION
 -----------
 
-Manage multiple worktrees attached to the same repository. These are
-created by the command `git checkout --to`.
+Manage multiple worktrees attached to the same repository.
 
 A git repository can support multiple working trees, allowing you to check
 out more than one branch at a time.  With `git checkout --to` a new working
@@ -45,6 +45,12 @@ pruning should be suppressed. See section "DETAILS" for more information.
 
 COMMANDS
 --------
+add <path> <branch>::
+
+Create `<path>` and checkout `<branch>` into it. The new working directory
+is linked to the current repository, sharing everything except working
+directory specific files such as HEAD, index, etc.
+
 prune::
 
 Prune working tree information in $GIT_DIR/worktrees.
@@ -118,7 +124,7 @@ refactoring session.
 
 ------------
 $ git branch emergency-fix master
-$ git checkout --to ../temp emergency-fix
+$ git worktree add ../temp emergency-fix
 $ pushd ../temp
 # ... hack hack hack ...
 $ git commit -a -m 'emergency fix for boss'
@@ -133,9 +139,8 @@ Multiple checkout support for submodules is incomplete. It is NOT
 recommended to make multiple checkouts of a superproject.
 
 git-worktree could provide more automation for tasks currently
-performed manually or via other commands, such as:
+performed manually, such as:
 
-- `add` to create a new linked worktree
 - `remove` to remove a linked worktree and its administrative files (and
   warn if the worktree is dirty)
 - `mv` to move or rename a worktree and update its administrative files
@@ -143,11 +148,6 @@ performed manually or via other commands, such as:
 - `lock` to prevent automatic pruning of administrative files (for instance,
   for a worktree on a portable device)
 
-SEE ALSO
---------
-
-linkgit:git-checkout[1]
-
 GIT
 ---
 Part of the linkgit:git[1] suite
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 2a729c661..e0749c099 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -2,8 +2,11 @@
 #include "builtin.h"
 #include "dir.h"
 #include "parse-options.h"
+#include "argv-array.h"
+#include "run-command.h"
 
 static const char * const worktree_usage[] = {
+	N_("git worktree add <path> <branch>"),
 	N_("git worktree prune [<options>]"),
 	NULL
 };
@@ -119,6 +122,32 @@ static int prune(int ac, const char **av, const char *prefix)
 	return 0;
 }
 
+static int add(int ac, const char **av, const char *prefix)
+{
+	struct child_process c;
+	const char *path, *branch;
+	struct argv_array cmd = ARGV_ARRAY_INIT;
+	struct option options[] = {
+		OPT_END()
+	};
+
+	ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
+	if (ac != 2)
+		usage_with_options(worktree_usage, options);
+
+	path = prefix ? prefix_filename(prefix, strlen(prefix), av[0]) : av[0];
+	branch = av[1];
+
+	argv_array_push(&cmd, "checkout");
+	argv_array_pushl(&cmd, "--to", path, NULL);
+	argv_array_push(&cmd, branch);
+
+	memset(&c, 0, sizeof(c));
+	c.git_cmd = 1;
+	c.argv = cmd.argv;
+	return run_command(&c);
+}
+
 int cmd_worktree(int ac, const char **av, const char *prefix)
 {
 	struct option options[] = {
@@ -127,6 +156,8 @@ int cmd_worktree(int ac, const char **av, const char *prefix)
 
 	if (ac < 2)
 		usage_with_options(worktree_usage, options);
+	if (!strcmp(av[1], "add"))
+		return add(ac - 1, av + 1, prefix);
 	if (!strcmp(av[1], "prune"))
 		return prune(ac - 1, av + 1, prefix);
 	usage_with_options(worktree_usage, options);
-- 
cgit v1.2.1


From f43254440d56da1fd52216cbebd5c285b20985e6 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:51 -0400
Subject: worktree: add --force option

By default, "git worktree add" refuses to create a new worktree when
the requested branch is already checked out elsewhere. Add a --force
option to override this safeguard.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 8 +++++++-
 builtin/worktree.c             | 6 +++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index def3027c4..8891de040 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -9,7 +9,7 @@ git-worktree - Manage multiple worktrees
 SYNOPSIS
 --------
 [verse]
-'git worktree add' <path> <branch>
+'git worktree add' [-f] <path> <branch>
 'git worktree prune' [-n] [-v] [--expire <expire>]
 
 DESCRIPTION
@@ -58,6 +58,12 @@ Prune working tree information in $GIT_DIR/worktrees.
 OPTIONS
 -------
 
+-f::
+--force::
+	By default, `add` refuses to create a new worktree when	`<branch>`
+	is already checked out by another worktree. This option overrides
+	that safeguard.
+
 -n::
 --dry-run::
 	With `prune`, do not remove anything; just report what it would
diff --git a/builtin/worktree.c b/builtin/worktree.c
index e0749c099..8c35023a4 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -6,7 +6,7 @@
 #include "run-command.h"
 
 static const char * const worktree_usage[] = {
-	N_("git worktree add <path> <branch>"),
+	N_("git worktree add [<options>] <path> <branch>"),
 	N_("git worktree prune [<options>]"),
 	NULL
 };
@@ -125,9 +125,11 @@ static int prune(int ac, const char **av, const char *prefix)
 static int add(int ac, const char **av, const char *prefix)
 {
 	struct child_process c;
+	int force = 0;
 	const char *path, *branch;
 	struct argv_array cmd = ARGV_ARRAY_INIT;
 	struct option options[] = {
+		OPT__FORCE(&force, N_("checkout <branch> even if already checked out in other worktree")),
 		OPT_END()
 	};
 
@@ -140,6 +142,8 @@ static int add(int ac, const char **av, const char *prefix)
 
 	argv_array_push(&cmd, "checkout");
 	argv_array_pushl(&cmd, "--to", path, NULL);
+	if (force)
+		argv_array_push(&cmd, "--ignore-other-worktrees");
 	argv_array_push(&cmd, branch);
 
 	memset(&c, 0, sizeof(c));
-- 
cgit v1.2.1


From 39ecb27436296361371d3caadcc9bc4a4e0b556d Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:52 -0400
Subject: worktree: add --detach option

One of git-worktree's roles is to populate the new worktree, much like
git-checkout, and thus, for convenience, ought to support several of the
same shortcuts. Toward this goal, add a --detach option to detach HEAD
in the new worktree.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 6 +++++-
 builtin/worktree.c             | 5 ++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 8891de040..231271b2f 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -9,7 +9,7 @@ git-worktree - Manage multiple worktrees
 SYNOPSIS
 --------
 [verse]
-'git worktree add' [-f] <path> <branch>
+'git worktree add' [-f] [--detach] <path> <branch>
 'git worktree prune' [-n] [-v] [--expire <expire>]
 
 DESCRIPTION
@@ -64,6 +64,10 @@ OPTIONS
 	is already checked out by another worktree. This option overrides
 	that safeguard.
 
+--detach::
+	With `add`, detach HEAD in the new worktree. See "DETACHED HEAD" in
+	linkgit:git-checkout[1].
+
 -n::
 --dry-run::
 	With `prune`, do not remove anything; just report what it would
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 8c35023a4..9dc92b07a 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -125,11 +125,12 @@ static int prune(int ac, const char **av, const char *prefix)
 static int add(int ac, const char **av, const char *prefix)
 {
 	struct child_process c;
-	int force = 0;
+	int force = 0, detach = 0;
 	const char *path, *branch;
 	struct argv_array cmd = ARGV_ARRAY_INIT;
 	struct option options[] = {
 		OPT__FORCE(&force, N_("checkout <branch> even if already checked out in other worktree")),
+		OPT_BOOL(0, "detach", &detach, N_("detach HEAD at named commit")),
 		OPT_END()
 	};
 
@@ -144,6 +145,8 @@ static int add(int ac, const char **av, const char *prefix)
 	argv_array_pushl(&cmd, "--to", path, NULL);
 	if (force)
 		argv_array_push(&cmd, "--ignore-other-worktrees");
+	if (detach)
+		argv_array_push(&cmd, "--detach");
 	argv_array_push(&cmd, branch);
 
 	memset(&c, 0, sizeof(c));
-- 
cgit v1.2.1


From cbdf60fa183e3a2330849046846b400ef4a99c3b Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:53 -0400
Subject: worktree: add -b/-B options

One of git-worktree's roles is to populate the new worktree, much like
git-checkout, and thus, for convenience, ought to support several of the
same shortcuts. Toward this goal, add -b/-B options to create a new
branch and check it out in the new worktree.

(For brevity, only -b is mentioned in the synopsis; -B is omitted.)

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 13 ++++++++++---
 builtin/worktree.c             | 11 +++++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 231271b2f..f44cd7878 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -9,7 +9,7 @@ git-worktree - Manage multiple worktrees
 SYNOPSIS
 --------
 [verse]
-'git worktree add' [-f] [--detach] <path> <branch>
+'git worktree add' [-f] [--detach] [-b <new-branch>] <path> <branch>
 'git worktree prune' [-n] [-v] [--expire <expire>]
 
 DESCRIPTION
@@ -64,6 +64,14 @@ OPTIONS
 	is already checked out by another worktree. This option overrides
 	that safeguard.
 
+-b <new-branch>::
+-B <new-branch>::
+	With `add`, create a new branch named `<new-branch>` starting at
+	`<branch>`, and check out `<new-branch>` into the new worktree.
+	By default, `-b` refuses to create a new branch if it already
+	exists. `-B` overrides this safeguard, resetting `<new-branch>` to
+	`<branch>`.
+
 --detach::
 	With `add`, detach HEAD in the new worktree. See "DETACHED HEAD" in
 	linkgit:git-checkout[1].
@@ -133,8 +141,7 @@ make the emergency fix, remove it when done, and then resume your earlier
 refactoring session.
 
 ------------
-$ git branch emergency-fix master
-$ git worktree add ../temp emergency-fix
+$ git worktree add -b emergency-fix ../temp master
 $ pushd ../temp
 # ... hack hack hack ...
 $ git commit -a -m 'emergency fix for boss'
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 9dc92b07a..d6d0eee3c 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -126,15 +126,22 @@ static int add(int ac, const char **av, const char *prefix)
 {
 	struct child_process c;
 	int force = 0, detach = 0;
+	const char *new_branch = NULL, *new_branch_force = NULL;
 	const char *path, *branch;
 	struct argv_array cmd = ARGV_ARRAY_INIT;
 	struct option options[] = {
 		OPT__FORCE(&force, N_("checkout <branch> even if already checked out in other worktree")),
+		OPT_STRING('b', NULL, &new_branch, N_("branch"),
+			   N_("create a new branch")),
+		OPT_STRING('B', NULL, &new_branch_force, N_("branch"),
+			   N_("create or reset a branch")),
 		OPT_BOOL(0, "detach", &detach, N_("detach HEAD at named commit")),
 		OPT_END()
 	};
 
 	ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
+	if (new_branch && new_branch_force)
+		die(_("-b and -B are mutually exclusive"));
 	if (ac != 2)
 		usage_with_options(worktree_usage, options);
 
@@ -145,6 +152,10 @@ static int add(int ac, const char **av, const char *prefix)
 	argv_array_pushl(&cmd, "--to", path, NULL);
 	if (force)
 		argv_array_push(&cmd, "--ignore-other-worktrees");
+	if (new_branch)
+		argv_array_pushl(&cmd, "-b", new_branch, NULL);
+	if (new_branch_force)
+		argv_array_pushl(&cmd, "-B", new_branch_force, NULL);
 	if (detach)
 		argv_array_push(&cmd, "--detach");
 	argv_array_push(&cmd, branch);
-- 
cgit v1.2.1


From f194b1ef6ee81788a45053fa6f7409233fc54276 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:54 -0400
Subject: tests: worktree: retrofit "checkout --to" tests for "worktree add"

With the introduction of "git worktree add", "git checkout --to" is
slated for removal. Therefore, retrofit linked worktree creation tests
to use "git worktree add" instead.

(The test to check exclusivity of "checkout --to" and "checkout <paths>"
is dropped altogether since it becomes meaningless with retirement of
"checkout --to".)

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/t2025-checkout-to.sh            | 147 --------------------------------------
 t/t2025-worktree-add.sh           | 143 ++++++++++++++++++++++++++++++++++++
 t/t2026-prune-linked-checkouts.sh |   2 +-
 t/t7410-submodule-checkout-to.sh  |   4 +-
 4 files changed, 146 insertions(+), 150 deletions(-)
 delete mode 100755 t/t2025-checkout-to.sh
 create mode 100755 t/t2025-worktree-add.sh

diff --git a/t/t2025-checkout-to.sh b/t/t2025-checkout-to.sh
deleted file mode 100755
index 0fd731b4b..000000000
--- a/t/t2025-checkout-to.sh
+++ /dev/null
@@ -1,147 +0,0 @@
-#!/bin/sh
-
-test_description='test git checkout --to'
-
-. ./test-lib.sh
-
-test_expect_success 'setup' '
-	test_commit init
-'
-
-test_expect_success 'checkout --to not updating paths' '
-	test_must_fail git checkout --to -- init.t
-'
-
-test_expect_success 'checkout --to an existing worktree' '
-	mkdir -p existing/subtree &&
-	test_must_fail git checkout --detach --to existing master
-'
-
-test_expect_success 'checkout --to an existing empty worktree' '
-	mkdir existing_empty &&
-	git checkout --detach --to existing_empty master
-'
-
-test_expect_success 'checkout --to refuses to checkout locked branch' '
-	test_must_fail git checkout --to zere master &&
-	! test -d zere &&
-	! test -d .git/worktrees/zere
-'
-
-test_expect_success 'checking out paths not complaining about linked checkouts' '
-	(
-	cd existing_empty &&
-	echo dirty >>init.t &&
-	git checkout master -- init.t
-	)
-'
-
-test_expect_success 'checkout --to a new worktree' '
-	git rev-parse HEAD >expect &&
-	git checkout --detach --to here master &&
-	(
-		cd here &&
-		test_cmp ../init.t init.t &&
-		test_must_fail git symbolic-ref HEAD &&
-		git rev-parse HEAD >actual &&
-		test_cmp ../expect actual &&
-		git fsck
-	)
-'
-
-test_expect_success 'checkout --to a new worktree from a subdir' '
-	(
-		mkdir sub &&
-		cd sub &&
-		git checkout --detach --to here master &&
-		cd here &&
-		test_cmp ../../init.t init.t
-	)
-'
-
-test_expect_success 'checkout --to from a linked checkout' '
-	(
-		cd here &&
-		git checkout --detach --to nested-here master &&
-		cd nested-here &&
-		git fsck
-	)
-'
-
-test_expect_success 'checkout --to a new worktree creating new branch' '
-	git checkout --to there -b newmaster master &&
-	(
-		cd there &&
-		test_cmp ../init.t init.t &&
-		git symbolic-ref HEAD >actual &&
-		echo refs/heads/newmaster >expect &&
-		test_cmp expect actual &&
-		git fsck
-	)
-'
-
-test_expect_success 'die the same branch is already checked out' '
-	(
-		cd here &&
-		test_must_fail git checkout newmaster
-	)
-'
-
-test_expect_success 'not die the same branch is already checked out' '
-	(
-		cd here &&
-		git checkout --ignore-other-worktrees --to anothernewmaster newmaster
-	)
-'
-
-test_expect_success 'not die on re-checking out current branch' '
-	(
-		cd there &&
-		git checkout newmaster
-	)
-'
-
-test_expect_success 'checkout --to from a bare repo' '
-	(
-		git clone --bare . bare &&
-		cd bare &&
-		git checkout --to ../there2 -b bare-master master
-	)
-'
-
-test_expect_success 'checkout from a bare repo without --to' '
-	(
-		cd bare &&
-		test_must_fail git checkout master
-	)
-'
-
-test_expect_success 'checkout with grafts' '
-	test_when_finished rm .git/info/grafts &&
-	test_commit abc &&
-	SHA1=`git rev-parse HEAD` &&
-	test_commit def &&
-	test_commit xyz &&
-	echo "`git rev-parse HEAD` $SHA1" >.git/info/grafts &&
-	cat >expected <<-\EOF &&
-	xyz
-	abc
-	EOF
-	git log --format=%s -2 >actual &&
-	test_cmp expected actual &&
-	git checkout --detach --to grafted master &&
-	git --git-dir=grafted/.git log --format=%s -2 >actual &&
-	test_cmp expected actual
-'
-
-test_expect_success 'checkout --to from relative HEAD' '
-	test_commit a &&
-	test_commit b &&
-	test_commit c &&
-	git rev-parse HEAD~1 >expected &&
-	git checkout --to relhead HEAD~1 &&
-	git -C relhead rev-parse HEAD >actual &&
-	test_cmp expected actual
-'
-
-test_done
diff --git a/t/t2025-worktree-add.sh b/t/t2025-worktree-add.sh
new file mode 100755
index 000000000..192c93673
--- /dev/null
+++ b/t/t2025-worktree-add.sh
@@ -0,0 +1,143 @@
+#!/bin/sh
+
+test_description='test git worktree add'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit init
+'
+
+test_expect_success '"add" an existing worktree' '
+	mkdir -p existing/subtree &&
+	test_must_fail git worktree add --detach existing master
+'
+
+test_expect_success '"add" an existing empty worktree' '
+	mkdir existing_empty &&
+	git worktree add --detach existing_empty master
+'
+
+test_expect_success '"add" refuses to checkout locked branch' '
+	test_must_fail git worktree add zere master &&
+	! test -d zere &&
+	! test -d .git/worktrees/zere
+'
+
+test_expect_success 'checking out paths not complaining about linked checkouts' '
+	(
+	cd existing_empty &&
+	echo dirty >>init.t &&
+	git checkout master -- init.t
+	)
+'
+
+test_expect_success '"add" worktree' '
+	git rev-parse HEAD >expect &&
+	git worktree add --detach here master &&
+	(
+		cd here &&
+		test_cmp ../init.t init.t &&
+		test_must_fail git symbolic-ref HEAD &&
+		git rev-parse HEAD >actual &&
+		test_cmp ../expect actual &&
+		git fsck
+	)
+'
+
+test_expect_success '"add" worktree from a subdir' '
+	(
+		mkdir sub &&
+		cd sub &&
+		git worktree add --detach here master &&
+		cd here &&
+		test_cmp ../../init.t init.t
+	)
+'
+
+test_expect_success '"add" from a linked checkout' '
+	(
+		cd here &&
+		git worktree add --detach nested-here master &&
+		cd nested-here &&
+		git fsck
+	)
+'
+
+test_expect_success '"add" worktree creating new branch' '
+	git worktree add -b newmaster there master &&
+	(
+		cd there &&
+		test_cmp ../init.t init.t &&
+		git symbolic-ref HEAD >actual &&
+		echo refs/heads/newmaster >expect &&
+		test_cmp expect actual &&
+		git fsck
+	)
+'
+
+test_expect_success 'die the same branch is already checked out' '
+	(
+		cd here &&
+		test_must_fail git checkout newmaster
+	)
+'
+
+test_expect_success 'not die the same branch is already checked out' '
+	(
+		cd here &&
+		git worktree add --force anothernewmaster newmaster
+	)
+'
+
+test_expect_success 'not die on re-checking out current branch' '
+	(
+		cd there &&
+		git checkout newmaster
+	)
+'
+
+test_expect_success '"add" from a bare repo' '
+	(
+		git clone --bare . bare &&
+		cd bare &&
+		git worktree add -b bare-master ../there2 master
+	)
+'
+
+test_expect_success 'checkout from a bare repo without "add"' '
+	(
+		cd bare &&
+		test_must_fail git checkout master
+	)
+'
+
+test_expect_success 'checkout with grafts' '
+	test_when_finished rm .git/info/grafts &&
+	test_commit abc &&
+	SHA1=`git rev-parse HEAD` &&
+	test_commit def &&
+	test_commit xyz &&
+	echo "`git rev-parse HEAD` $SHA1" >.git/info/grafts &&
+	cat >expected <<-\EOF &&
+	xyz
+	abc
+	EOF
+	git log --format=%s -2 >actual &&
+	test_cmp expected actual &&
+	git worktree add --detach grafted master &&
+	git --git-dir=grafted/.git log --format=%s -2 >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success '"add" from relative HEAD' '
+	test_commit a &&
+	test_commit b &&
+	test_commit c &&
+	git rev-parse HEAD~1 >expected &&
+	git worktree add relhead HEAD~1 &&
+	git -C relhead rev-parse HEAD >actual &&
+	test_cmp expected actual
+'
+
+test_done
diff --git a/t/t2026-prune-linked-checkouts.sh b/t/t2026-prune-linked-checkouts.sh
index e872f02da..a0f1e3bb8 100755
--- a/t/t2026-prune-linked-checkouts.sh
+++ b/t/t2026-prune-linked-checkouts.sh
@@ -88,7 +88,7 @@ test_expect_success 'not prune recent checkouts' '
 
 test_expect_success 'not prune proper checkouts' '
 	test_when_finished rm -r .git/worktrees &&
-	git checkout "--to=$PWD/nop" --detach master &&
+	git worktree add --detach "$PWD/nop" master &&
 	git worktree prune &&
 	test -d .git/worktrees/nop
 '
diff --git a/t/t7410-submodule-checkout-to.sh b/t/t7410-submodule-checkout-to.sh
index 8f30aed6c..3f609e890 100755
--- a/t/t7410-submodule-checkout-to.sh
+++ b/t/t7410-submodule-checkout-to.sh
@@ -33,7 +33,7 @@ rev1_hash_sub=$(git --git-dir=origin/sub/.git show --pretty=format:%h -q "HEAD~1
 test_expect_success 'checkout main' \
     'mkdir default_checkout &&
     (cd clone/main &&
-	git checkout --to "$base_path/default_checkout/main" "$rev1_hash_main")'
+	git worktree add "$base_path/default_checkout/main" "$rev1_hash_main")'
 
 test_expect_failure 'can see submodule diffs just after checkout' \
     '(cd default_checkout/main && git diff --submodule master"^!" | grep "file1 updated")'
@@ -41,7 +41,7 @@ test_expect_failure 'can see submodule diffs just after checkout' \
 test_expect_success 'checkout main and initialize independed clones' \
     'mkdir fully_cloned_submodule &&
     (cd clone/main &&
-	git checkout --to "$base_path/fully_cloned_submodule/main" "$rev1_hash_main") &&
+	git worktree add "$base_path/fully_cloned_submodule/main" "$rev1_hash_main") &&
     (cd fully_cloned_submodule/main && git submodule update)'
 
 test_expect_success 'can see submodule diffs after independed cloning' \
-- 
cgit v1.2.1


From b979d95027242455b10e6f566b0e96c5f30cc908 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:55 -0400
Subject: checkout: retire --to option

Now that "git worktree add" has achieved user-facing feature-parity with
"git checkout --to", retire the latter.

Move the actual linked worktree creation functionality,
prepare_linked_checkout() and its helpers, verbatim from checkout.c to
worktree.c.

This effectively reverts changes to checkout.c by 529fef2 (checkout:
support checking out into a new working directory, 2014-11-30) with the
exception of merge_working_tree() and switch_branches() which still
require specialized knowledge that a the checkout is occurring in a
newly-created linked worktree (signaled to them by the private
GIT_CHECKOUT_NEW_WORKTREE environment variable).

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-checkout.txt |   7 --
 builtin/checkout.c             | 161 +----------------------------------------
 builtin/worktree.c             | 144 ++++++++++++++++++++++++++++++++++--
 3 files changed, 139 insertions(+), 173 deletions(-)

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 77b7141f0..efe6a026f 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -225,13 +225,6 @@ This means that you can use `git checkout -p` to selectively discard
 edits from your current working tree. See the ``Interactive Mode''
 section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
 
---to=<path>::
-	Check out a branch in a separate working directory at
-	`<path>`. A new working directory is linked to the current
-	repository, sharing everything except working directory
-	specific files such as HEAD, index, etc. See
-	linkgit:git-worktree[1] for a description of linked worktrees.
-
 --ignore-other-worktrees::
 	`git checkout` refuses when the wanted ref is already checked
 	out by another worktree. This option makes it check the ref
diff --git a/builtin/checkout.c b/builtin/checkout.c
index e4064a84c..b1e68b326 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -19,8 +19,6 @@
 #include "ll-merge.h"
 #include "resolve-undo.h"
 #include "submodule.h"
-#include "argv-array.h"
-#include "sigchain.h"
 
 static const char * const checkout_usage[] = {
 	N_("git checkout [options] <branch>"),
@@ -51,8 +49,6 @@ struct checkout_opts {
 	struct pathspec pathspec;
 	struct tree *source_tree;
 
-	const char *new_worktree;
-	const char **saved_argv;
 	int new_worktree_mode;
 };
 
@@ -255,9 +251,6 @@ static int checkout_paths(const struct checkout_opts *opts,
 		die(_("Cannot update paths and switch to branch '%s' at the same time."),
 		    opts->new_branch);
 
-	if (opts->new_worktree)
-		die(_("'%s' cannot be used with updating paths"), "--to");
-
 	if (opts->patch_mode)
 		return run_add_interactive(revision, "--patch=checkout",
 					   &opts->pathspec);
@@ -825,142 +818,6 @@ static int switch_branches(const struct checkout_opts *opts,
 	return ret || writeout_error;
 }
 
-static char *junk_work_tree;
-static char *junk_git_dir;
-static int is_junk;
-static pid_t junk_pid;
-
-static void remove_junk(void)
-{
-	struct strbuf sb = STRBUF_INIT;
-	if (!is_junk || getpid() != junk_pid)
-		return;
-	if (junk_git_dir) {
-		strbuf_addstr(&sb, junk_git_dir);
-		remove_dir_recursively(&sb, 0);
-		strbuf_reset(&sb);
-	}
-	if (junk_work_tree) {
-		strbuf_addstr(&sb, junk_work_tree);
-		remove_dir_recursively(&sb, 0);
-	}
-	strbuf_release(&sb);
-}
-
-static void remove_junk_on_signal(int signo)
-{
-	remove_junk();
-	sigchain_pop(signo);
-	raise(signo);
-}
-
-static int prepare_linked_checkout(const char *path, const char **child_argv)
-{
-	struct strbuf sb_git = STRBUF_INIT, sb_repo = STRBUF_INIT;
-	struct strbuf sb = STRBUF_INIT;
-	const char *name;
-	struct stat st;
-	struct child_process cp;
-	int counter = 0, len, ret;
-	unsigned char rev[20];
-
-	if (file_exists(path) && !is_empty_dir(path))
-		die(_("'%s' already exists"), path);
-
-	len = strlen(path);
-	while (len && is_dir_sep(path[len - 1]))
-		len--;
-
-	for (name = path + len - 1; name > path; name--)
-		if (is_dir_sep(*name)) {
-			name++;
-			break;
-		}
-	strbuf_addstr(&sb_repo,
-		      git_path("worktrees/%.*s", (int)(path + len - name), name));
-	len = sb_repo.len;
-	if (safe_create_leading_directories_const(sb_repo.buf))
-		die_errno(_("could not create leading directories of '%s'"),
-			  sb_repo.buf);
-	while (!stat(sb_repo.buf, &st)) {
-		counter++;
-		strbuf_setlen(&sb_repo, len);
-		strbuf_addf(&sb_repo, "%d", counter);
-	}
-	name = strrchr(sb_repo.buf, '/') + 1;
-
-	junk_pid = getpid();
-	atexit(remove_junk);
-	sigchain_push_common(remove_junk_on_signal);
-
-	if (mkdir(sb_repo.buf, 0777))
-		die_errno(_("could not create directory of '%s'"), sb_repo.buf);
-	junk_git_dir = xstrdup(sb_repo.buf);
-	is_junk = 1;
-
-	/*
-	 * lock the incomplete repo so prune won't delete it, unlock
-	 * after the preparation is over.
-	 */
-	strbuf_addf(&sb, "%s/locked", sb_repo.buf);
-	write_file(sb.buf, 1, "initializing\n");
-
-	strbuf_addf(&sb_git, "%s/.git", path);
-	if (safe_create_leading_directories_const(sb_git.buf))
-		die_errno(_("could not create leading directories of '%s'"),
-			  sb_git.buf);
-	junk_work_tree = xstrdup(path);
-
-	strbuf_reset(&sb);
-	strbuf_addf(&sb, "%s/gitdir", sb_repo.buf);
-	write_file(sb.buf, 1, "%s\n", real_path(sb_git.buf));
-	write_file(sb_git.buf, 1, "gitdir: %s/worktrees/%s\n",
-		   real_path(get_git_common_dir()), name);
-	/*
-	 * This is to keep resolve_ref() happy. We need a valid HEAD
-	 * or is_git_directory() will reject the directory. Moreover, HEAD
-	 * in the new worktree must resolve to the same value as HEAD in
-	 * the current tree since the command invoked to populate the new
-	 * worktree will be handed the branch/ref specified by the user.
-	 * For instance, if the user asks for the new worktree to be based
-	 * at HEAD~5, then the resolved HEAD~5 in the new worktree must
-	 * match the resolved HEAD~5 in the current tree in order to match
-	 * the user's expectation.
-	 */
-	if (!resolve_ref_unsafe("HEAD", 0, rev, NULL))
-		die(_("unable to resolve HEAD"));
-	strbuf_reset(&sb);
-	strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
-	write_file(sb.buf, 1, "%s\n", sha1_to_hex(rev));
-	strbuf_reset(&sb);
-	strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
-	write_file(sb.buf, 1, "../..\n");
-
-	fprintf_ln(stderr, _("Enter %s (identifier %s)"), path, name);
-
-	setenv("GIT_CHECKOUT_NEW_WORKTREE", "1", 1);
-	setenv(GIT_DIR_ENVIRONMENT, sb_git.buf, 1);
-	setenv(GIT_WORK_TREE_ENVIRONMENT, path, 1);
-	memset(&cp, 0, sizeof(cp));
-	cp.git_cmd = 1;
-	cp.argv = child_argv;
-	ret = run_command(&cp);
-	if (!ret) {
-		is_junk = 0;
-		free(junk_work_tree);
-		free(junk_git_dir);
-		junk_work_tree = NULL;
-		junk_git_dir = NULL;
-	}
-	strbuf_reset(&sb);
-	strbuf_addf(&sb, "%s/locked", sb_repo.buf);
-	unlink_or_warn(sb.buf);
-	strbuf_release(&sb);
-	strbuf_release(&sb_repo);
-	strbuf_release(&sb_git);
-	return ret;
-}
-
 static int git_checkout_config(const char *var, const char *value, void *cb)
 {
 	if (!strcmp(var, "diff.ignoresubmodules")) {
@@ -1299,13 +1156,6 @@ static int checkout_branch(struct checkout_opts *opts,
 		free(head_ref);
 	}
 
-	if (opts->new_worktree) {
-		if (!new->commit)
-			die(_("no branch specified"));
-		return prepare_linked_checkout(opts->new_worktree,
-					       opts->saved_argv);
-	}
-
 	if (!new->commit && opts->new_branch) {
 		unsigned char rev[20];
 		int flag;
@@ -1348,8 +1198,6 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 			 N_("do not limit pathspecs to sparse entries only")),
 		OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
 				N_("second guess 'git checkout no-such-branch'")),
-		OPT_FILENAME(0, "to", &opts.new_worktree,
-			   N_("check a branch out in a separate working directory")),
 		OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
 			 N_("do not check if another worktree is holding the given ref")),
 		OPT_END(),
@@ -1360,9 +1208,6 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	opts.overwrite_ignore = 1;
 	opts.prefix = prefix;
 
-	opts.saved_argv = xmalloc(sizeof(const char *) * (argc + 2));
-	memcpy(opts.saved_argv, argv, sizeof(const char *) * (argc + 1));
-
 	gitmodules_config();
 	git_config(git_checkout_config, &opts);
 
@@ -1371,13 +1216,9 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options, checkout_usage,
 			     PARSE_OPT_KEEP_DASHDASH);
 
-	/* recursive execution from checkout_new_worktree() */
 	opts.new_worktree_mode = getenv("GIT_CHECKOUT_NEW_WORKTREE") != NULL;
-	if (opts.new_worktree_mode)
-		opts.new_worktree = NULL;
 
-	if (!opts.new_worktree)
-		setup_work_tree();
+	setup_work_tree();
 
 	if (conflict_style) {
 		opts.merge = 1; /* implied */
diff --git a/builtin/worktree.c b/builtin/worktree.c
index d6d0eee3c..04e6d0f92 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -4,6 +4,7 @@
 #include "parse-options.h"
 #include "argv-array.h"
 #include "run-command.h"
+#include "sigchain.h"
 
 static const char * const worktree_usage[] = {
 	N_("git worktree add [<options>] <path> <branch>"),
@@ -122,9 +123,144 @@ static int prune(int ac, const char **av, const char *prefix)
 	return 0;
 }
 
+static char *junk_work_tree;
+static char *junk_git_dir;
+static int is_junk;
+static pid_t junk_pid;
+
+static void remove_junk(void)
+{
+	struct strbuf sb = STRBUF_INIT;
+	if (!is_junk || getpid() != junk_pid)
+		return;
+	if (junk_git_dir) {
+		strbuf_addstr(&sb, junk_git_dir);
+		remove_dir_recursively(&sb, 0);
+		strbuf_reset(&sb);
+	}
+	if (junk_work_tree) {
+		strbuf_addstr(&sb, junk_work_tree);
+		remove_dir_recursively(&sb, 0);
+	}
+	strbuf_release(&sb);
+}
+
+static void remove_junk_on_signal(int signo)
+{
+	remove_junk();
+	sigchain_pop(signo);
+	raise(signo);
+}
+
+static int add_worktree(const char *path, const char **child_argv)
+{
+	struct strbuf sb_git = STRBUF_INIT, sb_repo = STRBUF_INIT;
+	struct strbuf sb = STRBUF_INIT;
+	const char *name;
+	struct stat st;
+	struct child_process cp;
+	int counter = 0, len, ret;
+	unsigned char rev[20];
+
+	if (file_exists(path) && !is_empty_dir(path))
+		die(_("'%s' already exists"), path);
+
+	len = strlen(path);
+	while (len && is_dir_sep(path[len - 1]))
+		len--;
+
+	for (name = path + len - 1; name > path; name--)
+		if (is_dir_sep(*name)) {
+			name++;
+			break;
+		}
+	strbuf_addstr(&sb_repo,
+		      git_path("worktrees/%.*s", (int)(path + len - name), name));
+	len = sb_repo.len;
+	if (safe_create_leading_directories_const(sb_repo.buf))
+		die_errno(_("could not create leading directories of '%s'"),
+			  sb_repo.buf);
+	while (!stat(sb_repo.buf, &st)) {
+		counter++;
+		strbuf_setlen(&sb_repo, len);
+		strbuf_addf(&sb_repo, "%d", counter);
+	}
+	name = strrchr(sb_repo.buf, '/') + 1;
+
+	junk_pid = getpid();
+	atexit(remove_junk);
+	sigchain_push_common(remove_junk_on_signal);
+
+	if (mkdir(sb_repo.buf, 0777))
+		die_errno(_("could not create directory of '%s'"), sb_repo.buf);
+	junk_git_dir = xstrdup(sb_repo.buf);
+	is_junk = 1;
+
+	/*
+	 * lock the incomplete repo so prune won't delete it, unlock
+	 * after the preparation is over.
+	 */
+	strbuf_addf(&sb, "%s/locked", sb_repo.buf);
+	write_file(sb.buf, 1, "initializing\n");
+
+	strbuf_addf(&sb_git, "%s/.git", path);
+	if (safe_create_leading_directories_const(sb_git.buf))
+		die_errno(_("could not create leading directories of '%s'"),
+			  sb_git.buf);
+	junk_work_tree = xstrdup(path);
+
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "%s/gitdir", sb_repo.buf);
+	write_file(sb.buf, 1, "%s\n", real_path(sb_git.buf));
+	write_file(sb_git.buf, 1, "gitdir: %s/worktrees/%s\n",
+		   real_path(get_git_common_dir()), name);
+	/*
+	 * This is to keep resolve_ref() happy. We need a valid HEAD
+	 * or is_git_directory() will reject the directory. Moreover, HEAD
+	 * in the new worktree must resolve to the same value as HEAD in
+	 * the current tree since the command invoked to populate the new
+	 * worktree will be handed the branch/ref specified by the user.
+	 * For instance, if the user asks for the new worktree to be based
+	 * at HEAD~5, then the resolved HEAD~5 in the new worktree must
+	 * match the resolved HEAD~5 in the current tree in order to match
+	 * the user's expectation.
+	 */
+	if (!resolve_ref_unsafe("HEAD", 0, rev, NULL))
+		die(_("unable to resolve HEAD"));
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
+	write_file(sb.buf, 1, "%s\n", sha1_to_hex(rev));
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
+	write_file(sb.buf, 1, "../..\n");
+
+	fprintf_ln(stderr, _("Enter %s (identifier %s)"), path, name);
+
+	setenv("GIT_CHECKOUT_NEW_WORKTREE", "1", 1);
+	setenv(GIT_DIR_ENVIRONMENT, sb_git.buf, 1);
+	setenv(GIT_WORK_TREE_ENVIRONMENT, path, 1);
+	memset(&cp, 0, sizeof(cp));
+	cp.git_cmd = 1;
+	cp.argv = child_argv;
+	ret = run_command(&cp);
+	if (!ret) {
+		is_junk = 0;
+		free(junk_work_tree);
+		free(junk_git_dir);
+		junk_work_tree = NULL;
+		junk_git_dir = NULL;
+	}
+	strbuf_reset(&sb);
+	strbuf_addf(&sb, "%s/locked", sb_repo.buf);
+	unlink_or_warn(sb.buf);
+	strbuf_release(&sb);
+	strbuf_release(&sb_repo);
+	strbuf_release(&sb_git);
+	return ret;
+}
+
 static int add(int ac, const char **av, const char *prefix)
 {
-	struct child_process c;
 	int force = 0, detach = 0;
 	const char *new_branch = NULL, *new_branch_force = NULL;
 	const char *path, *branch;
@@ -149,7 +285,6 @@ static int add(int ac, const char **av, const char *prefix)
 	branch = av[1];
 
 	argv_array_push(&cmd, "checkout");
-	argv_array_pushl(&cmd, "--to", path, NULL);
 	if (force)
 		argv_array_push(&cmd, "--ignore-other-worktrees");
 	if (new_branch)
@@ -160,10 +295,7 @@ static int add(int ac, const char **av, const char *prefix)
 		argv_array_push(&cmd, "--detach");
 	argv_array_push(&cmd, branch);
 
-	memset(&c, 0, sizeof(c));
-	c.git_cmd = 1;
-	c.argv = cmd.argv;
-	return run_command(&c);
+	return add_worktree(path, cmd.argv);
 }
 
 int cmd_worktree(int ac, const char **av, const char *prefix)
-- 
cgit v1.2.1


From 0ca560cb975aa081971d0fb1586e0206156fa22f Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:56 -0400
Subject: checkout: require worktree unconditionally

In order to allow linked worktree creation via "git checkout --to" from
a bare repository, 3473ad0 (checkout: don't require a work tree when
checking out into a new one, 2014-11-30) dropped git-checkout's
unconditional NEED_WORK_TREE requirement and instead performed worktree
setup conditionally based upon presence or absence of the --to option.
Now that --to has been retired and git-checkout is no longer responsible
for linked worktree creation, the NEED_WORK_TREE requirement can be
re-instated.

This effectively reverts 3473ad0, except for the tests it added which
now check bare repository behavior of "git worktree add" instead.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/checkout.c | 2 --
 git.c              | 2 +-
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/builtin/checkout.c b/builtin/checkout.c
index b1e68b326..57545543e 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -1218,8 +1218,6 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 
 	opts.new_worktree_mode = getenv("GIT_CHECKOUT_NEW_WORKTREE") != NULL;
 
-	setup_work_tree();
-
 	if (conflict_style) {
 		opts.merge = 1; /* implied */
 		git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
diff --git a/git.c b/git.c
index f22783894..21a639844 100644
--- a/git.c
+++ b/git.c
@@ -383,7 +383,7 @@ static struct cmd_struct commands[] = {
 	{ "check-ignore", cmd_check_ignore, RUN_SETUP | NEED_WORK_TREE },
 	{ "check-mailmap", cmd_check_mailmap, RUN_SETUP },
 	{ "check-ref-format", cmd_check_ref_format },
-	{ "checkout", cmd_checkout, RUN_SETUP },
+	{ "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
 	{ "checkout-index", cmd_checkout_index,
 		RUN_SETUP | NEED_WORK_TREE},
 	{ "cherry", cmd_cherry, RUN_SETUP },
-- 
cgit v1.2.1


From f5682b2a861cbde6e9aca324caa5e2d36c49569a Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:57 -0400
Subject: worktree: extract basename computation to new function

A subsequent patch will also need to compute the basename of the new
worktree, so factor out this logic into a new function.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/worktree.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/builtin/worktree.c b/builtin/worktree.c
index 04e6d0f92..25fe25b45 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -152,6 +152,25 @@ static void remove_junk_on_signal(int signo)
 	raise(signo);
 }
 
+static const char *worktree_basename(const char *path, int *olen)
+{
+	const char *name;
+	int len;
+
+	len = strlen(path);
+	while (len && is_dir_sep(path[len - 1]))
+		len--;
+
+	for (name = path + len - 1; name > path; name--)
+		if (is_dir_sep(*name)) {
+			name++;
+			break;
+		}
+
+	*olen = len;
+	return name;
+}
+
 static int add_worktree(const char *path, const char **child_argv)
 {
 	struct strbuf sb_git = STRBUF_INIT, sb_repo = STRBUF_INIT;
@@ -165,15 +184,7 @@ static int add_worktree(const char *path, const char **child_argv)
 	if (file_exists(path) && !is_empty_dir(path))
 		die(_("'%s' already exists"), path);
 
-	len = strlen(path);
-	while (len && is_dir_sep(path[len - 1]))
-		len--;
-
-	for (name = path + len - 1; name > path; name--)
-		if (is_dir_sep(*name)) {
-			name++;
-			break;
-		}
+	name = worktree_basename(path, &len);
 	strbuf_addstr(&sb_repo,
 		      git_path("worktrees/%.*s", (int)(path + len - name), name));
 	len = sb_repo.len;
-- 
cgit v1.2.1


From 0f4af3b9ea1fc62e445271bb2e7fbb8e1ac230b7 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:58 -0400
Subject: worktree: add: make -b/-B default to HEAD when <branch> is omitted

As a convenience, like "git branch" and "git checkout -b", make
"git worktree add -b <newbranch> <path> <branch>" default to HEAD when
<branch> is omitted.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt | 1 +
 builtin/worktree.c             | 6 ++++--
 t/t2025-worktree-add.sh        | 5 +++++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index f44cd7878..377ae0f92 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -68,6 +68,7 @@ OPTIONS
 -B <new-branch>::
 	With `add`, create a new branch named `<new-branch>` starting at
 	`<branch>`, and check out `<new-branch>` into the new worktree.
+	If `<branch>` is omitted, it defaults to HEAD.
 	By default, `-b` refuses to create a new branch if it already
 	exists. `-B` overrides this safeguard, resetting `<new-branch>` to
 	`<branch>`.
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 25fe25b45..323d444b3 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -289,11 +289,13 @@ static int add(int ac, const char **av, const char *prefix)
 	ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
 	if (new_branch && new_branch_force)
 		die(_("-b and -B are mutually exclusive"));
-	if (ac != 2)
+	if (ac < 1 || ac > 2)
+		usage_with_options(worktree_usage, options);
+	if (ac < 2 && !new_branch && !new_branch_force)
 		usage_with_options(worktree_usage, options);
 
 	path = prefix ? prefix_filename(prefix, strlen(prefix), av[0]) : av[0];
-	branch = av[1];
+	branch = ac < 2 ? "HEAD" : av[1];
 
 	argv_array_push(&cmd, "checkout");
 	if (force)
diff --git a/t/t2025-worktree-add.sh b/t/t2025-worktree-add.sh
index 192c93673..8964dec75 100755
--- a/t/t2025-worktree-add.sh
+++ b/t/t2025-worktree-add.sh
@@ -140,4 +140,9 @@ test_expect_success '"add" from relative HEAD' '
 	test_cmp expected actual
 '
 
+test_expect_success '"add -b" with <branch> omitted' '
+	git worktree add -b burble flornk &&
+	test_cmp_rev HEAD burble
+'
+
 test_done
-- 
cgit v1.2.1


From 1eb07d829f3f0992c93c6b44fdcc4e95ebab12f3 Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:30:59 -0400
Subject: worktree: add: auto-vivify new branch when <branch> is omitted

As a convenience, when <branch> is omitted from "git worktree <path>
<branch>" and neither -b nor -B is used, automatically create a new
branch named after <path>, as if "-b $(basename <path>)" was specified.
Thus, "git worktree add ../hotfix" creates a new branch named "hotfix"
and associates it with new worktree "../hotfix".

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-worktree.txt |  8 ++++++--
 builtin/worktree.c             |  8 ++++++--
 t/t2025-worktree-add.sh        | 14 ++++++++++++++
 3 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-worktree.txt b/Documentation/git-worktree.txt
index 377ae0f92..da71f508b 100644
--- a/Documentation/git-worktree.txt
+++ b/Documentation/git-worktree.txt
@@ -9,7 +9,7 @@ git-worktree - Manage multiple worktrees
 SYNOPSIS
 --------
 [verse]
-'git worktree add' [-f] [--detach] [-b <new-branch>] <path> <branch>
+'git worktree add' [-f] [--detach] [-b <new-branch>] <path> [<branch>]
 'git worktree prune' [-n] [-v] [--expire <expire>]
 
 DESCRIPTION
@@ -45,11 +45,15 @@ pruning should be suppressed. See section "DETAILS" for more information.
 
 COMMANDS
 --------
-add <path> <branch>::
+add <path> [<branch>]::
 
 Create `<path>` and checkout `<branch>` into it. The new working directory
 is linked to the current repository, sharing everything except working
 directory specific files such as HEAD, index, etc.
++
+If `<branch>` is omitted and neither `-b` nor `-B` is used, then, as a
+convenience, a new branch based at HEAD is created automatically, as if
+`-b $(basename <path>)` was specified.
 
 prune::
 
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 323d444b3..69248ba0a 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -291,12 +291,16 @@ static int add(int ac, const char **av, const char *prefix)
 		die(_("-b and -B are mutually exclusive"));
 	if (ac < 1 || ac > 2)
 		usage_with_options(worktree_usage, options);
-	if (ac < 2 && !new_branch && !new_branch_force)
-		usage_with_options(worktree_usage, options);
 
 	path = prefix ? prefix_filename(prefix, strlen(prefix), av[0]) : av[0];
 	branch = ac < 2 ? "HEAD" : av[1];
 
+	if (ac < 2 && !new_branch && !new_branch_force) {
+		int n;
+		const char *s = worktree_basename(path, &n);
+		new_branch = xstrndup(s, n);
+	}
+
 	argv_array_push(&cmd, "checkout");
 	if (force)
 		argv_array_push(&cmd, "--ignore-other-worktrees");
diff --git a/t/t2025-worktree-add.sh b/t/t2025-worktree-add.sh
index 8964dec75..ead8aa2a9 100755
--- a/t/t2025-worktree-add.sh
+++ b/t/t2025-worktree-add.sh
@@ -145,4 +145,18 @@ test_expect_success '"add -b" with <branch> omitted' '
 	test_cmp_rev HEAD burble
 '
 
+test_expect_success '"add" with <branch> omitted' '
+	git worktree add wiffle/bat &&
+	test_cmp_rev HEAD bat
+'
+
+test_expect_success '"add" auto-vivify does not clobber existing branch' '
+	test_commit c1 &&
+	test_commit c2 &&
+	git branch precious HEAD~1 &&
+	test_must_fail git worktree add precious &&
+	test_cmp_rev HEAD~1 precious &&
+	test_path_is_missing precious
+'
+
 test_done
-- 
cgit v1.2.1


From 0d1a1517835a10818f2d40d8780a268dbb5e20ce Mon Sep 17 00:00:00 2001
From: Eric Sunshine <sunshine@sunshineco.com>
Date: Mon, 6 Jul 2015 13:31:00 -0400
Subject: checkout: retire --ignore-other-worktrees in favor of --force

As a safeguard, checking out a branch already checked out by a different
worktree is disallowed. This behavior can be overridden with
--ignore-other-worktrees, however, this option is neither obvious nor
particularly discoverable. As a common safeguard override, --force is
more likely to come to mind. Therefore, overload it to also suppress the
check for a branch already checked out elsewhere.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-checkout.txt | 9 +++------
 builtin/checkout.c             | 8 +++-----
 builtin/worktree.c             | 2 +-
 3 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index efe6a026f..6c3085d72 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -111,6 +111,9 @@ OPTIONS
 +
 When checking out paths from the index, do not fail upon unmerged
 entries; instead, unmerged entries are ignored.
++
+By default, checking out a branch already checked out in another worktree
+is disallowed. This overrides that safeguard.
 
 --ours::
 --theirs::
@@ -225,12 +228,6 @@ This means that you can use `git checkout -p` to selectively discard
 edits from your current working tree. See the ``Interactive Mode''
 section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
 
---ignore-other-worktrees::
-	`git checkout` refuses when the wanted ref is already checked
-	out by another worktree. This option makes it check the ref
-	out anyway. In other words, the ref can be held by more than one
-	worktree.
-
 <branch>::
 	Branch to checkout; if it refers to a branch (i.e., a name that,
 	when prepended with "refs/heads/", is a valid ref), then that
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 57545543e..01c7c30d5 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -35,7 +35,6 @@ struct checkout_opts {
 	int writeout_stage;
 	int overwrite_ignore;
 	int ignore_skipworktree;
-	int ignore_other_worktrees;
 
 	const char *new_branch;
 	const char *new_branch_force;
@@ -903,7 +902,8 @@ static void check_linked_checkout(struct branch_info *new, const char *id)
 		strbuf_rtrim(&gitdir);
 	} else
 		strbuf_addstr(&gitdir, get_git_common_dir());
-	die(_("'%s' is already checked out at '%s'"), new->name, gitdir.buf);
+	die(_("'%s' is already checked out at '%s'; use --force to override"),
+	    new->name, gitdir.buf);
 done:
 	strbuf_release(&path);
 	strbuf_release(&sb);
@@ -1151,7 +1151,7 @@ static int checkout_branch(struct checkout_opts *opts,
 		char *head_ref = resolve_refdup("HEAD", 0, sha1, &flag);
 		if (head_ref &&
 		    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)) &&
-		    !opts->ignore_other_worktrees)
+		    !opts->force)
 			check_linked_checkouts(new);
 		free(head_ref);
 	}
@@ -1198,8 +1198,6 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 			 N_("do not limit pathspecs to sparse entries only")),
 		OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
 				N_("second guess 'git checkout no-such-branch'")),
-		OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
-			 N_("do not check if another worktree is holding the given ref")),
 		OPT_END(),
 	};
 
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 69248ba0a..050b443dc 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -303,7 +303,7 @@ static int add(int ac, const char **av, const char *prefix)
 
 	argv_array_push(&cmd, "checkout");
 	if (force)
-		argv_array_push(&cmd, "--ignore-other-worktrees");
+		argv_array_push(&cmd, "--force");
 	if (new_branch)
 		argv_array_pushl(&cmd, "-b", new_branch, NULL);
 	if (new_branch_force)
-- 
cgit v1.2.1


From c925fe23684455735c3bb1903803643a24a58d8f Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Sun, 12 Jul 2015 09:38:21 -0700
Subject: Revert "checkout: retire --ignore-other-worktrees in favor of
 --force"

This reverts commit 0d1a1517835a10818f2d40d8780a268dbb5e20ce.

When trying to switch to a different branch, that happens to be
checked out in another working tree, the user shouldn't have to
give up the other safety measures (like protecting the local changes
that overlap the difference between the branches) while defeating
the "no two checkouts of the same branch" safety.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/git-checkout.txt | 9 ++++++---
 builtin/checkout.c             | 8 +++++---
 builtin/worktree.c             | 2 +-
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 6c3085d72..efe6a026f 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -111,9 +111,6 @@ OPTIONS
 +
 When checking out paths from the index, do not fail upon unmerged
 entries; instead, unmerged entries are ignored.
-+
-By default, checking out a branch already checked out in another worktree
-is disallowed. This overrides that safeguard.
 
 --ours::
 --theirs::
@@ -228,6 +225,12 @@ This means that you can use `git checkout -p` to selectively discard
 edits from your current working tree. See the ``Interactive Mode''
 section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
 
+--ignore-other-worktrees::
+	`git checkout` refuses when the wanted ref is already checked
+	out by another worktree. This option makes it check the ref
+	out anyway. In other words, the ref can be held by more than one
+	worktree.
+
 <branch>::
 	Branch to checkout; if it refers to a branch (i.e., a name that,
 	when prepended with "refs/heads/", is a valid ref), then that
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 01c7c30d5..57545543e 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -35,6 +35,7 @@ struct checkout_opts {
 	int writeout_stage;
 	int overwrite_ignore;
 	int ignore_skipworktree;
+	int ignore_other_worktrees;
 
 	const char *new_branch;
 	const char *new_branch_force;
@@ -902,8 +903,7 @@ static void check_linked_checkout(struct branch_info *new, const char *id)
 		strbuf_rtrim(&gitdir);
 	} else
 		strbuf_addstr(&gitdir, get_git_common_dir());
-	die(_("'%s' is already checked out at '%s'; use --force to override"),
-	    new->name, gitdir.buf);
+	die(_("'%s' is already checked out at '%s'"), new->name, gitdir.buf);
 done:
 	strbuf_release(&path);
 	strbuf_release(&sb);
@@ -1151,7 +1151,7 @@ static int checkout_branch(struct checkout_opts *opts,
 		char *head_ref = resolve_refdup("HEAD", 0, sha1, &flag);
 		if (head_ref &&
 		    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)) &&
-		    !opts->force)
+		    !opts->ignore_other_worktrees)
 			check_linked_checkouts(new);
 		free(head_ref);
 	}
@@ -1198,6 +1198,8 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 			 N_("do not limit pathspecs to sparse entries only")),
 		OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
 				N_("second guess 'git checkout no-such-branch'")),
+		OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
+			 N_("do not check if another worktree is holding the given ref")),
 		OPT_END(),
 	};
 
diff --git a/builtin/worktree.c b/builtin/worktree.c
index 050b443dc..69248ba0a 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -303,7 +303,7 @@ static int add(int ac, const char **av, const char *prefix)
 
 	argv_array_push(&cmd, "checkout");
 	if (force)
-		argv_array_push(&cmd, "--force");
+		argv_array_push(&cmd, "--ignore-other-worktrees");
 	if (new_branch)
 		argv_array_pushl(&cmd, "-b", new_branch, NULL);
 	if (new_branch_force)
-- 
cgit v1.2.1