Merge branch 'nd/multiple-work-trees'

A replacement for contrib/workdir/git-new-workdir that does not
rely on symbolic links and make sharing of objects and refs safer
by making the borrowee and borrowers aware of each other.

* nd/multiple-work-trees: (41 commits)
  prune --worktrees: fix expire vs worktree existence condition
  t1501: fix test with split index
  t2026: fix broken &&-chain
  t2026 needs procondition SANITY
  git-checkout.txt: a note about multiple checkout support for submodules
  checkout: add --ignore-other-wortrees
  checkout: pass whole struct to parse_branchname_arg instead of individual flags
  git-common-dir: make "modules/" per-working-directory directory
  checkout: do not fail if target is an empty directory
  t2025: add a test to make sure grafts is working from a linked checkout
  checkout: don't require a work tree when checking out into a new one
  git_path(): keep "info/sparse-checkout" per work-tree
  count-objects: report unused files in $GIT_DIR/worktrees/...
  gc: support prune --worktrees
  gc: factor out gc.pruneexpire parsing code
  gc: style change -- no SP before closing parenthesis
  checkout: clean up half-prepared directories in --to mode
  checkout: reject if the branch is already checked out elsewhere
  prune: strategies for linked checkouts
  checkout: support checking out into a new working directory
  ...

6 files changed, 389 insertions, 0 deletions

diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index c0143a0a70..93605f42f2 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -19,6 +19,14 @@ relative_path() {
 	"test \"\$(test-path-utils relative_path '$1' '$2')\" = '$expected'"
 }
 
+test_git_path() {
+	test_expect_success "git-path $1 $2 => $3" "
+		$1 git rev-parse --git-path $2 >actual &&
+		echo $3 >expect &&
+		test_cmp expect actual
+	"
+}
+
 # On Windows, we are using MSYS's bash, which mangles the paths.
 # Absolute paths are anchored at the MSYS installation directory,
 # which means that the path / accounts for this many characters:
@@ -244,4 +252,32 @@ relative_path "<null>"		"<empty>"	./
 relative_path "<null>"		"<null>"	./
 relative_path "<null>"		/foo/a/b	./
 
+test_git_path A=B                info/grafts .git/info/grafts
+test_git_path GIT_GRAFT_FILE=foo info/grafts foo
+test_git_path GIT_GRAFT_FILE=foo info/////grafts foo
+test_git_path GIT_INDEX_FILE=foo index foo
+test_git_path GIT_INDEX_FILE=foo index/foo .git/index/foo
+test_git_path GIT_INDEX_FILE=foo index2 .git/index2
+test_expect_success 'setup fake objects directory foo' 'mkdir foo'
+test_git_path GIT_OBJECT_DIRECTORY=foo objects foo
+test_git_path GIT_OBJECT_DIRECTORY=foo objects/foo foo/foo
+test_git_path GIT_OBJECT_DIRECTORY=foo objects2 .git/objects2
+test_expect_success 'setup common repository' 'git --git-dir=bar init'
+test_git_path GIT_COMMON_DIR=bar index                    .git/index
+test_git_path GIT_COMMON_DIR=bar HEAD                     .git/HEAD
+test_git_path GIT_COMMON_DIR=bar logs/HEAD                .git/logs/HEAD
+test_git_path GIT_COMMON_DIR=bar objects                  bar/objects
+test_git_path GIT_COMMON_DIR=bar objects/bar              bar/objects/bar
+test_git_path GIT_COMMON_DIR=bar info/exclude             bar/info/exclude
+test_git_path GIT_COMMON_DIR=bar info/grafts              bar/info/grafts
+test_git_path GIT_COMMON_DIR=bar info/sparse-checkout     .git/info/sparse-checkout
+test_git_path GIT_COMMON_DIR=bar remotes/bar              bar/remotes/bar
+test_git_path GIT_COMMON_DIR=bar branches/bar             bar/branches/bar
+test_git_path GIT_COMMON_DIR=bar logs/refs/heads/master   bar/logs/refs/heads/master
+test_git_path GIT_COMMON_DIR=bar refs/heads/master        bar/refs/heads/master
+test_git_path GIT_COMMON_DIR=bar hooks/me                 bar/hooks/me
+test_git_path GIT_COMMON_DIR=bar config                   bar/config
+test_git_path GIT_COMMON_DIR=bar packed-refs              bar/packed-refs
+test_git_path GIT_COMMON_DIR=bar shallow                  bar/shallow
+
 test_done
diff --git a/t/t1501-worktree.sh b/t/t1501-worktree.sh
index 8f36aa9fc4..cc5b870e58 100755
--- a/t/t1501-worktree.sh
+++ b/t/t1501-worktree.sh
@@ -346,4 +346,81 @@ test_expect_success 'relative $GIT_WORK_TREE and git subprocesses' '
 	test_cmp expected actual
 '
 
+test_expect_success 'Multi-worktree setup' '
+	mkdir work &&
+	mkdir -p repo.git/repos/foo &&
+	cp repo.git/HEAD repo.git/index repo.git/repos/foo &&
+	test_might_fail cp repo.git/sharedindex.* repo.git/repos/foo &&
+	sane_unset GIT_DIR GIT_CONFIG GIT_WORK_TREE
+'
+
+test_expect_success 'GIT_DIR set (1)' '
+	echo "gitdir: repo.git/repos/foo" >gitfile &&
+	echo ../.. >repo.git/repos/foo/commondir &&
+	(
+		cd work &&
+		GIT_DIR=../gitfile git rev-parse --git-common-dir >actual &&
+		test-path-utils real_path "$TRASH_DIRECTORY/repo.git" >expect &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'GIT_DIR set (2)' '
+	echo "gitdir: repo.git/repos/foo" >gitfile &&
+	echo "$(pwd)/repo.git" >repo.git/repos/foo/commondir &&
+	(
+		cd work &&
+		GIT_DIR=../gitfile git rev-parse --git-common-dir >actual &&
+		test-path-utils real_path "$TRASH_DIRECTORY/repo.git" >expect &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'Auto discovery' '
+	echo "gitdir: repo.git/repos/foo" >.git &&
+	echo ../.. >repo.git/repos/foo/commondir &&
+	(
+		cd work &&
+		git rev-parse --git-common-dir >actual &&
+		test-path-utils real_path "$TRASH_DIRECTORY/repo.git" >expect &&
+		test_cmp expect actual &&
+		echo haha >data1 &&
+		git add data1 &&
+		git ls-files --full-name :/ | grep data1 >actual &&
+		echo work/data1 >expect &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success '$GIT_DIR/common overrides core.worktree' '
+	mkdir elsewhere &&
+	git --git-dir=repo.git config core.worktree "$TRASH_DIRECTORY/elsewhere" &&
+	echo "gitdir: repo.git/repos/foo" >.git &&
+	echo ../.. >repo.git/repos/foo/commondir &&
+	(
+		cd work &&
+		git rev-parse --git-common-dir >actual &&
+		test-path-utils real_path "$TRASH_DIRECTORY/repo.git" >expect &&
+		test_cmp expect actual &&
+		echo haha >data2 &&
+		git add data2 &&
+		git ls-files --full-name :/ | grep data2 >actual &&
+		echo work/data2 >expect &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success '$GIT_WORK_TREE overrides $GIT_DIR/common' '
+	echo "gitdir: repo.git/repos/foo" >.git &&
+	echo ../.. >repo.git/repos/foo/commondir &&
+	(
+		cd work &&
+		echo haha >data3 &&
+		git --git-dir=../.git --work-tree=. add data3 &&
+		git ls-files --full-name -- :/ | grep data3 >actual &&
+		echo data3 >expect &&
+		test_cmp expect actual
+	)
+'
+
 test_done
diff --git a/t/t1510-repo-setup.sh b/t/t1510-repo-setup.sh
index e1b2a99f10..33c1a587b3 100755
--- a/t/t1510-repo-setup.sh
+++ b/t/t1510-repo-setup.sh
@@ -106,6 +106,7 @@ setup_env () {
 expect () {
 	cat >"$1/expected" <<-EOF
 	setup: git_dir: $2
+	setup: git_common_dir: $2
 	setup: worktree: $3
 	setup: cwd: $4
 	setup: prefix: $5
diff --git a/t/t2025-checkout-to.sh b/t/t2025-checkout-to.sh
new file mode 100755
index 0000000000..f8e4df4818
--- /dev/null
+++ b/t/t2025-checkout-to.sh
@@ -0,0 +1,129 @@
+#!/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 '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_done
diff --git a/t/t2026-prune-linked-checkouts.sh b/t/t2026-prune-linked-checkouts.sh
new file mode 100755
index 0000000000..1821a480c5
--- /dev/null
+++ b/t/t2026-prune-linked-checkouts.sh
@@ -0,0 +1,96 @@
+#!/bin/sh
+
+test_description='prune $GIT_DIR/worktrees'
+
+. ./test-lib.sh
+
+test_expect_success initialize '
+	git commit --allow-empty -m init
+'
+
+test_expect_success 'prune --worktrees on normal repo' '
+	git prune --worktrees &&
+	test_must_fail git prune --worktrees abc
+'
+
+test_expect_success 'prune files inside $GIT_DIR/worktrees' '
+	mkdir .git/worktrees &&
+	: >.git/worktrees/abc &&
+	git prune --worktrees --verbose >actual &&
+	cat >expect <<EOF &&
+Removing worktrees/abc: not a valid directory
+EOF
+	test_i18ncmp expect actual &&
+	! test -f .git/worktrees/abc &&
+	! test -d .git/worktrees
+'
+
+test_expect_success 'prune directories without gitdir' '
+	mkdir -p .git/worktrees/def/abc &&
+	: >.git/worktrees/def/def &&
+	cat >expect <<EOF &&
+Removing worktrees/def: gitdir file does not exist
+EOF
+	git prune --worktrees --verbose >actual &&
+	test_i18ncmp expect actual &&
+	! test -d .git/worktrees/def &&
+	! test -d .git/worktrees
+'
+
+test_expect_success SANITY 'prune directories with unreadable gitdir' '
+	mkdir -p .git/worktrees/def/abc &&
+	: >.git/worktrees/def/def &&
+	: >.git/worktrees/def/gitdir &&
+	chmod u-r .git/worktrees/def/gitdir &&
+	git prune --worktrees --verbose >actual &&
+	test_i18ngrep "Removing worktrees/def: unable to read gitdir file" actual &&
+	! test -d .git/worktrees/def &&
+	! test -d .git/worktrees
+'
+
+test_expect_success 'prune directories with invalid gitdir' '
+	mkdir -p .git/worktrees/def/abc &&
+	: >.git/worktrees/def/def &&
+	: >.git/worktrees/def/gitdir &&
+	git prune --worktrees --verbose >actual &&
+	test_i18ngrep "Removing worktrees/def: invalid gitdir file" actual &&
+	! test -d .git/worktrees/def &&
+	! test -d .git/worktrees
+'
+
+test_expect_success 'prune directories with gitdir pointing to nowhere' '
+	mkdir -p .git/worktrees/def/abc &&
+	: >.git/worktrees/def/def &&
+	echo "$(pwd)"/nowhere >.git/worktrees/def/gitdir &&
+	git prune --worktrees --verbose >actual &&
+	test_i18ngrep "Removing worktrees/def: gitdir file points to non-existent location" actual &&
+	! test -d .git/worktrees/def &&
+	! test -d .git/worktrees
+'
+
+test_expect_success 'not prune locked checkout' '
+	test_when_finished rm -r .git/worktrees &&
+	mkdir -p .git/worktrees/ghi &&
+	: >.git/worktrees/ghi/locked &&
+	git prune --worktrees &&
+	test -d .git/worktrees/ghi
+'
+
+test_expect_success 'not prune recent checkouts' '
+	test_when_finished rm -r .git/worktrees &&
+	mkdir zz &&
+	mkdir -p .git/worktrees/jlm &&
+	echo "$(pwd)"/zz >.git/worktrees/jlm/gitdir &&
+	rmdir zz &&
+	git prune --worktrees --verbose --expire=2.days.ago &&
+	test -d .git/worktrees/jlm
+'
+
+test_expect_success 'not prune proper checkouts' '
+	test_when_finished rm -r .git/worktrees &&
+	git checkout "--to=$PWD/nop" --detach master &&
+	git prune --worktrees &&
+	test -d .git/worktrees/nop
+'
+
+test_done
diff --git a/t/t7410-submodule-checkout-to.sh b/t/t7410-submodule-checkout-to.sh
new file mode 100755
index 0000000000..8f30aed6cc
--- /dev/null
+++ b/t/t7410-submodule-checkout-to.sh
@@ -0,0 +1,50 @@
+#!/bin/sh
+
+test_description='Combination of submodules and multiple workdirs'
+
+. ./test-lib.sh
+
+base_path=$(pwd -P)
+
+test_expect_success 'setup: make origin' \
+    'mkdir -p origin/sub && ( cd origin/sub && git init &&
+	echo file1 >file1 &&
+	git add file1 &&
+	git commit -m file1 ) &&
+    mkdir -p origin/main && ( cd origin/main && git init &&
+	git submodule add ../sub &&
+	git commit -m "add sub" ) &&
+    ( cd origin/sub &&
+	echo file1updated >file1 &&
+	git add file1 &&
+	git commit -m "file1 updated" ) &&
+    ( cd origin/main/sub && git pull ) &&
+    ( cd origin/main &&
+	git add sub &&
+	git commit -m "sub updated" )'
+
+test_expect_success 'setup: clone' \
+    'mkdir clone && ( cd clone &&
+	git clone --recursive "$base_path/origin/main")'
+
+rev1_hash_main=$(git --git-dir=origin/main/.git show --pretty=format:%h -q "HEAD~1")
+rev1_hash_sub=$(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")'
+
+test_expect_failure 'can see submodule diffs just after checkout' \
+    '(cd default_checkout/main && git diff --submodule master"^!" | grep "file1 updated")'
+
+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") &&
+    (cd fully_cloned_submodule/main && git submodule update)'
+
+test_expect_success 'can see submodule diffs after independed cloning' \
+    '(cd fully_cloned_submodule/main && git diff --submodule master"^!" | grep "file1 updated")'
+
+test_done