Merge branch 'nd/switch-and-restore'

Two new commands "git switch" and "git restore" are introduced to
split "checking out a branch to work on advancing its history" and
"checking out paths out of the index and/or a tree-ish to work on
advancing the current history" out of the single "git checkout"
command.

* nd/switch-and-restore: (46 commits)
  completion: disable dwim on "git switch -d"
  switch: allow to switch in the middle of bisect
  t2027: use test_must_be_empty
  Declare both git-switch and git-restore experimental
  help: move git-diff and git-reset to different groups
  doc: promote "git restore"
  user-manual.txt: prefer 'merge --abort' over 'reset --hard'
  completion: support restore
  t: add tests for restore
  restore: support --patch
  restore: replace --force with --ignore-unmerged
  restore: default to --source=HEAD when only --staged is specified
  restore: reject invalid combinations with --staged
  restore: add --worktree and --staged
  checkout: factor out worktree checkout code
  restore: disable overlay mode by default
  restore: make pathspec mandatory
  restore: take tree-ish from --source option instead
  checkout: split part of it to new command 'restore'
  doc: promote "git switch"
  ...

Author: gitster

.gitignore

@@ -139,6 +139,7 @@
 /git-request-pull
 /git-rerere
 /git-reset
+/git-restore
 /git-rev-list
 /git-rev-parse
 /git-revert
@@ -163,6 +164,7 @@
 /git-submodule
 /git-submodule--helper
 /git-svn
+/git-switch
 /git-symbolic-ref
 /git-tag
 /git-unpack-file

Documentation/config/advice.txt

@@ -42,7 +42,8 @@ advice.*::
 		state in the output of linkgit:git-status[1], in
 		the template shown when writing commit messages in
 		linkgit:git-commit[1], and in the help message shown
-		by linkgit:git-checkout[1] when switching branch.
+		by linkgit:git-switch[1] or
+		linkgit:git-checkout[1] when switching branch.
 	statusUoption::
 		Advise to consider using the `-u` option to linkgit:git-status[1]
 		when the command takes more than 2 seconds to enumerate untracked
@@ -62,12 +63,14 @@ advice.*::
 		your information is guessed from the system username and
 		domain name.
 	detachedHead::
-		Advice shown when you used linkgit:git-checkout[1] to
-		move to the detach HEAD state, to instruct how to create
-		a local branch after the fact.
+		Advice shown when you used
+		linkgit:git-switch[1] or linkgit:git-checkout[1]
+		to move to the detach HEAD state, to instruct how to
+		create a local branch after the fact.
 	checkoutAmbiguousRemoteBranchName::
 		Advice shown when the argument to
-		linkgit:git-checkout[1] ambiguously resolves to a
+		linkgit:git-checkout[1] and linkgit:git-switch[1]
+		ambiguously resolves to a
 		remote tracking branch on more than one remote in
 		situations where an unambiguous argument would have
 		otherwise caused a remote-tracking branch to be

Documentation/config/branch.txt

@@ -1,5 +1,5 @@
 branch.autoSetupMerge::
-	Tells 'git branch' and 'git checkout' to set up new branches
+	Tells 'git branch', 'git switch' and 'git checkout' to set up new branches
 	so that linkgit:git-pull[1] will appropriately merge from the
 	starting point branch. Note that even if this option is not set,
 	this behavior can be chosen per-branch using the `--track`
@@ -11,7 +11,7 @@ branch.autoSetupMerge::
 	branch. This option defaults to true.
 
 branch.autoSetupRebase::
-	When a new branch is created with 'git branch' or 'git checkout'
+	When a new branch is created with 'git branch', 'git switch' or 'git checkout'
 	that tracks another branch, this variable tells Git to set
 	up pull to rebase instead of merge (see "branch.<name>.rebase").
 	When `never`, rebase is never automatically set to true.

Documentation/config/checkout.txt

@@ -1,5 +1,6 @@
 checkout.defaultRemote::
-	When you run 'git checkout <something>' and only have one
+	When you run 'git checkout <something>'
+	or 'git switch <something>' and only have one
 	remote, it may implicitly fall back on checking out and
 	tracking e.g. 'origin/<something>'. This stops working as soon
 	as you have more than one remote with a '<something>'
@@ -8,16 +9,10 @@ checkout.defaultRemote::
 	disambiguation. The typical use-case is to set this to
 	`origin`.
 +
-Currently this is used by linkgit:git-checkout[1] when 'git checkout
-<something>' will checkout the '<something>' branch on another remote,
+Currently this is used by linkgit:git-switch[1] and
+linkgit:git-checkout[1] when 'git checkout <something>'
+or 'git switch <something>'
+will checkout the '<something>' branch on another remote,
 and by linkgit:git-worktree[1] when 'git worktree add' refers to a
 remote branch. This setting might be used for other checkout-like
 commands or functionality in the future.
-
-checkout.optimizeNewBranch::
-	Optimizes the performance of "git checkout -b <new_branch>" when
-	using sparse-checkout.  When set to true, git will not update the
-	repo based on the current sparse-checkout settings.  This means it
-	will not update the skip-worktree bit in the index nor add/remove
-	files in the working directory to reflect the current sparse checkout
-	settings nor will it show the local changes.

Documentation/config/diff.txt

@@ -78,7 +78,8 @@ diff.external::
 diff.ignoreSubmodules::
 	Sets the default value of --ignore-submodules. Note that this
 	affects only 'git diff' Porcelain, and not lower level 'diff'
-	commands such as 'git diff-files'. 'git checkout' also honors
+	commands such as 'git diff-files'. 'git checkout'
+	and 'git switch' also honor
 	this setting when reporting uncommitted changes. Setting it to
 	'all' disables the submodule summary normally shown by 'git commit'
 	and 'git status' when `status.submoduleSummary` is set unless it is

Documentation/config/interactive.txt

@@ -2,7 +2,8 @@ interactive.singleKey::
 	In interactive commands, allow the user to provide one-letter
 	input with a single key (i.e., without hitting enter).
 	Currently this is used by the `--patch` mode of
-	linkgit:git-add[1], linkgit:git-checkout[1], linkgit:git-commit[1],
+	linkgit:git-add[1], linkgit:git-checkout[1],
+	linkgit:git-restore[1], linkgit:git-commit[1],
 	linkgit:git-reset[1], and linkgit:git-stash[1]. Note that this
 	setting is silently ignored if portable keystroke input
 	is not available; requires the Perl module Term::ReadKey.

Documentation/git-branch.txt

@@ -60,7 +60,7 @@ can leave out at most one of `A` and `B`, in which case it defaults to
 `HEAD`.
 
 Note that this will create the new branch, but it will not switch the
-working tree to it; use "git checkout <newbranch>" to switch to the
+working tree to it; use "git switch <newbranch>" to switch to the
 new branch.
 
 When a local branch is started off a remote-tracking branch, Git sets up the
@@ -214,7 +214,7 @@ This option is only applicable in non-verbose mode.
 +
 This behavior is the default when the start point is a remote-tracking branch.
 Set the branch.autoSetupMerge configuration variable to `false` if you
-want `git checkout` and `git branch` to always behave as if `--no-track`
+want `git switch`, `git checkout` and `git branch` to always behave as if `--no-track`
 were given. Set it to `always` if you want this behavior when the
 start-point is either a local or remote-tracking branch.
 
@@ -313,7 +313,7 @@ Start development from a known tag::
 $ git clone git://git.kernel.org/pub/scm/.../linux-2.6 my2.6
 $ cd my2.6
 $ git branch my2.6.14 v2.6.14   <1>
-$ git checkout my2.6.14
+$ git switch my2.6.14
 ------------
 +
 <1> This step and the next one could be combined into a single step with
@@ -350,9 +350,9 @@ Patterns will normally need quoting.
 NOTES
 -----
 
-If you are creating a branch that you want to checkout immediately, it is
-easier to use the git checkout command with its `-b` option to create
-a branch and check it out with a single command.
+If you are creating a branch that you want to switch to immediately,
+it is easier to use the "git switch" command with its `-c` option to
+do the same thing with a single command.
 
 The options `--contains`, `--no-contains`, `--merged` and `--no-merged`
 serve four related but different purposes:

Documentation/git-check-ref-format.txt

@@ -88,7 +88,8 @@ but it is explicitly forbidden at the beginning of a branch name).
 When run with `--branch` option in a repository, the input is first
 expanded for the ``previous checkout syntax''
 `@{-n}`.  For example, `@{-1}` is a way to refer the last thing that
-was checked out using "git checkout" operation. This option should be
+was checked out using "git switch" or "git checkout" operation.
+This option should be
 used by porcelains to accept this syntax anywhere a branch name is
 expected, so they can act as if you typed the branch name. As an
 exception note that, the ``previous checkout operation'' might result