Subject: setup: officially support --work-tree without --git-dir

The original intention of --work-tree was to allow people to work in a
subdirectory of their working tree that does not have an embedded .git
directory.  Because their working tree, which their $cwd was in, did not
have an embedded .git, they needed to use $GIT_DIR to specify where it is,
and because this meant there was no way to discover where the root level
of the working tree was, so we needed to add $GIT_WORK_TREE to tell git
where it was.

However, this facility has long been (mis)used by people's scripts to
start git from a working tree _with_ an embedded .git directory, let git
find .git directory, and then pretend as if an unrelated directory were
the associated working tree of the .git directory found by the discovery
process.  It happens to work in simple cases, and is not worth causing
"regression" to these scripts.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 134 insertions, 95 deletions

diff --git a/setup.c b/setup.c
index 3d732697a..dadc66659 100644
--- a/setup.c
+++ b/setup.c
@@ -411,6 +411,15 @@ static const char *setup_discovered_git_dir(const char *gitdir,
 	if (check_repository_format_gently(gitdir, nongit_ok))
 		return NULL;
 
+	/* --work-tree is set without --git-dir; use discovered one */
+	if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
+		if (offset != len && !is_absolute_path(gitdir))
+			gitdir = xstrdup(make_absolute_path(gitdir));
+		if (chdir(cwd))
+			die_errno("Could not come back to cwd");
+		return setup_explicit_git_dir(gitdir, cwd, len, nongit_ok);
+	}
+
 	/* #16.2, #17.2, #20.2, #21.2, #24, #25, #28, #29 (see t1510) */
 	if (is_bare_repository_cfg > 0) {
 		set_git_dir(offset == len ? gitdir : make_absolute_path(gitdir));
@@ -443,6 +452,16 @@ static const char *setup_bare_git_dir(char *cwd, int offset, int len, int *nongi
 	if (check_repository_format_gently(".", nongit_ok))
 		return NULL;
 
+	/* --work-tree is set without --git-dir; use discovered one */
+	if (getenv(GIT_WORK_TREE_ENVIRONMENT) || git_work_tree_cfg) {
+		const char *gitdir;
+
+		gitdir = offset == len ? "." : xmemdupz(cwd, offset);
+		if (chdir(cwd))
+			die_errno("Could not come back to cwd");
+		return setup_explicit_git_dir(gitdir, cwd, len, nongit_ok);
+	}
+
 	inside_git_dir = 1;
 	inside_work_tree = 0;
 	if (offset != len) {
diff --git a/t/t1510-repo-setup.sh b/t/t1510-repo-setup.sh
index 4f8f9760a..dcc0f86bd 100755
--- a/t/t1510-repo-setup.sh
+++ b/t/t1510-repo-setup.sh
@@ -16,8 +16,12 @@ A few rules for repo setup:
 4. GIT_WORK_TREE is relative to user's cwd. --work-tree is
    equivalent to GIT_WORK_TREE.
 
-5. GIT_WORK_TREE/core.worktree is only effective if GIT_DIR is set
-   Uneffective worktree settings should be warned.
+5. GIT_WORK_TREE/core.worktree was originally meant to work only if
+   GIT_DIR is set, but earlier git didn't enforce it, and some scripts
+   depend on the implementation that happened to first discover .git by
+   going up from the users $cwd and then using the specified working tree
+   that may or may not have any relation to where .git was found in.  This
+   historical behaviour must be kept.
 
 6. Effective GIT_WORK_TREE overrides core.worktree and core.bare
 
@@ -224,13 +228,16 @@ try_repo () {
 test_expect_success '#0: nonbare repo, no explicit configuration' '
 	try_repo 0 unset unset unset "" unset \
 		.git "$here/0" "$here/0" "(null)" \
-		.git "$here/0" "$here/0" sub/
+		.git "$here/0" "$here/0" sub/ 2>message &&
+	! test -s message
 '
 
-test_expect_success '#1: GIT_WORK_TREE without explicit GIT_DIR is ignored' '
-	try_repo 1 non-existent unset unset "" unset \
-		.git "$here/1" "$here/1" "(null)" \
-		.git "$here/1" "$here/1" sub/
+test_expect_success '#1: GIT_WORK_TREE without explicit GIT_DIR is accepted' '
+	mkdir -p wt &&
+	try_repo 1 "$here" unset unset "" unset \
+		"$here/1/.git" "$here" "$here" 1/ \
+		"$here/1/.git" "$here" "$here" 1/sub/ 2>message &&
+	! test -s message
 '
 
 test_expect_success '#2: worktree defaults to cwd with explicit GIT_DIR' '
@@ -251,17 +258,24 @@ test_expect_success '#3: setup' '
 '
 run_wt_tests 3
 
-test_expect_success '#4: core.worktree without GIT_DIR set is ignored' '
-	try_repo 4 unset unset non-existent "" unset \
-		.git "$here/4" "$here/4" "(null)" \
-		.git "$here/4" "$here/4" sub/
+test_expect_success '#4: core.worktree without GIT_DIR set is accepted' '
+	setup_repo 4 ../sub "" unset &&
+	mkdir -p 4/sub sub &&
+	try_case 4 unset unset \
+		.git "$here/4/sub" "$here/4" "(null)" \
+		"$here/4/.git" "$here/4/sub" "$here/4/sub" "(null)" 2>message &&
+	! test -s message
 '
 
-test_expect_success '#5: core.worktree + GIT_WORK_TREE is still ignored' '
+test_expect_success '#5: core.worktree + GIT_WORK_TREE is accepted' '
 	# or: you cannot intimidate away the lack of GIT_DIR setting
-	try_repo 5 non-existent-too unset non-existent "" unset \
-		.git "$here/5" "$here/5" "(null)" \
-		.git "$here/5" "$here/5" sub/
+	try_repo 5 "$here" unset "$here/5" "" unset \
+		"$here/5/.git" "$here" "$here" 5/ \
+		"$here/5/.git" "$here" "$here" 5/sub/ 2>message &&
+	try_repo 5a .. unset "$here/5a" "" unset \
+		"$here/5a/.git" "$here" "$here" 5a/ \
+		"$here/5a/.git" "$here/5a" "$here/5a" sub/ &&
+	! test -s message
 '
 
 test_expect_success '#6: setting GIT_DIR brings core.worktree to life' '
@@ -353,10 +367,12 @@ test_expect_success '#8: gitfile, easy case' '
 		"$here/8.git" "$here/8" "$here/8" sub/
 '
 
-test_expect_success '#9: GIT_WORK_TREE ignored even with gitfile' '
-	try_repo 9 non-existent unset unset gitfile unset \
-		"$here/9.git" "$here/9" "$here/9" "(null)" \
-		"$here/9.git" "$here/9" "$here/9" sub/
+test_expect_success '#9: GIT_WORK_TREE accepted with gitfile' '
+	mkdir -p 9/wt &&
+	try_repo 9 wt unset unset gitfile unset \
+		"$here/9.git" "$here/9/wt" "$here/9" "(null)" \
+		"$here/9.git" "$here/9/sub/wt" "$here/9/sub" "(null)" 2>message &&
+	! test -s message
 '
 
 test_expect_success '#10: GIT_DIR can point to gitfile' '
@@ -378,17 +394,19 @@ test_expect_success '#11: setup' '
 '
 run_wt_tests 11 gitfile
 
-test_expect_success '#12: core.worktree with gitfile is still ignored' '
-	try_repo 12 unset unset non-existent gitfile unset \
+test_expect_success '#12: core.worktree with gitfile is accepted' '
+	try_repo 12 unset unset "$here/12" gitfile unset \
 		"$here/12.git" "$here/12" "$here/12" "(null)" \
-		"$here/12.git" "$here/12" "$here/12" sub/
+		"$here/12.git" "$here/12" "$here/12" sub/ 2>message &&
+	! test -s message
 '
 
-test_expect_success '#13: core.worktree+GIT_WORK_TREE ignored (with gitfile)' '
+test_expect_success '#13: core.worktree+GIT_WORK_TREE accepted (with gitfile)' '
 	# or: you cannot intimidate away the lack of GIT_DIR setting
 	try_repo 13 non-existent-too unset non-existent gitfile unset \
-		"$here/13.git" "$here/13" "$here/13" "(null)" \
-		"$here/13.git" "$here/13" "$here/13" sub/
+		"$here/13.git" "$here/13/non-existent-too" "$here/13" "(null)" \
+		"$here/13.git" "$here/13/sub/non-existent-too" "$here/13/sub" "(null)" 2>message &&
+	! test -s message
 '
 
 # case #14.
@@ -499,30 +517,32 @@ test_expect_success '#16c: bare .git has no worktree' '
 		"$here/16c/.git" "(null)" "$here/16c/sub" "(null)"
 '
 
-test_expect_success '#17: GIT_WORK_TREE without explicit GIT_DIR is ignored (bare case)' '
+test_expect_success '#17: GIT_WORK_TREE without explicit GIT_DIR is accepted (bare case)' '
 	# Just like #16.
 	setup_repo 17a unset "" true &&
 	setup_repo 17b unset "" true &&
 	mkdir -p 17a/.git/wt/sub &&
 	mkdir -p 17b/.git/wt/sub &&
 
-	try_case 17a/.git non-existent unset \
-		. "(null)" "$here/17a/.git" "(null)" &&
-	try_case 17a/.git/wt non-existent unset \
-		"$here/17a/.git" "(null)" "$here/17a/.git/wt" "(null)" &&
-	try_case 17a/.git/wt/sub non-existent unset \
-		"$here/17a/.git" "(null)" "$here/17a/.git/wt/sub" "(null)" &&
+	try_case 17a/.git "$here/17a" unset \
+		"$here/17a/.git" "$here/17a" "$here/17a" .git/ \
+		2>message &&
+	try_case 17a/.git/wt "$here/17a" unset \
+		"$here/17a/.git" "$here/17a" "$here/17a" .git/wt/ &&
+	try_case 17a/.git/wt/sub "$here/17a" unset \
+		"$here/17a/.git" "$here/17a" "$here/17a" .git/wt/sub/ &&
 
-	try_case 17b/.git non-existent unset \
-		. "(null)" "$here/17b/.git" "(null)" &&
-	try_case 17b/.git/wt non-existent unset \
-		"$here/17b/.git" "(null)" "$here/17b/.git/wt" "(null)" &&
-	try_case 17b/.git/wt/sub non-existent unset \
-		"$here/17b/.git" "(null)" "$here/17b/.git/wt/sub" "(null)" &&
+	try_case 17b/.git "$here/17b" unset \
+		"$here/17b/.git" "$here/17b" "$here/17b" .git/ &&
+	try_case 17b/.git/wt "$here/17b" unset \
+		"$here/17b/.git" "$here/17b" "$here/17b" .git/wt/ &&
+	try_case 17b/.git/wt/sub "$here/17b" unset \
+		"$here/17b/.git" "$here/17b" "$here/17b" .git/wt/sub/ &&
 
-	try_repo 17c non-existent unset unset "" true \
-		.git "(null)" "$here/17c" "(null)" \
-		"$here/17c/.git" "(null)" "$here/17c/sub" "(null)"
+	try_repo 17c "$here/17c" unset unset "" true \
+		.git "$here/17c" "$here/17c" "(null)" \
+		"$here/17c/.git" "$here/17c" "$here/17c" sub/ 2>message &&
+	! test -s message
 '
 
 test_expect_success '#18: bare .git named by GIT_DIR has no worktree' '
@@ -541,56 +561,43 @@ test_expect_success '#19: setup' '
 '
 run_wt_tests 19
 
-test_expect_success '#20a: core.worktree without GIT_DIR ignored (inside .git)' '
-	# Just like case #16a.
-	setup_repo 20a non-existent "" unset &&
+test_expect_success '#20a: core.worktree without GIT_DIR accepted (inside .git)' '
+	# Unlike case #16a.
+	setup_repo 20a "$here/20a" "" unset &&
 	mkdir -p 20a/.git/wt/sub &&
 	try_case 20a/.git unset unset \
-		. "(null)" "$here/20a/.git" "(null)" &&
+		"$here/20a/.git" "$here/20a" "$here/20a" .git/ 2>message &&
 	try_case 20a/.git/wt unset unset \
-		"$here/20a/.git" "(null)" "$here/20a/.git/wt" "(null)" &&
+		"$here/20a/.git" "$here/20a" "$here/20a" .git/wt/ &&
 	try_case 20a/.git/wt/sub unset unset \
-		"$here/20a/.git" "(null)" "$here/20a/.git/wt/sub" "(null)"
+		"$here/20a/.git" "$here/20a" "$here/20a" .git/wt/sub/ &&
+	! test -s message
 '
 
-test_expect_success '#20b/c: core.worktree without GIT_DIR ignored (bare repository)' '
-	# Just like case #16b/c.
+test_expect_success '#20b/c: core.worktree and core.bare conflict' '
 	setup_repo 20b non-existent "" true &&
 	mkdir -p 20b/.git/wt/sub &&
-	try_case 20b/.git unset unset \
-		. "(null)" "$here/20b/.git" "(null)" &&
-	try_case 20b/.git/wt unset unset \
-		"$here/20b/.git" "(null)" "$here/20b/.git/wt" "(null)" &&
-	try_case 20b/.git/wt/sub unset unset \
-		"$here/20b/.git" "(null)" "$here/20b/.git/wt/sub" "(null)" &&
-	try_repo 20c unset unset non-existent "" true \
-		.git "(null)" "$here/20c" "(null)" \
-		"$here/20c/.git" "(null)" "$here/20c/sub" "(null)"
-'
-
-test_expect_success '#21: core.worktree+GIT_WORK_TREE without GIT_DIR ignored (bare cases)' '
-	setup_repo 21a non-existent "" unset &&
-	mkdir -p 21a/.git/wt/sub &&
-	try_case 21a/.git non-existent-too unset \
-		. "(null)" "$here/21a/.git" "(null)" &&
-	try_case 21a/.git/wt non-existent-too unset \
-		"$here/21a/.git" "(null)" "$here/21a/.git/wt" "(null)" &&
-	try_case 21a/.git/wt/sub non-existent-too unset \
-		"$here/21a/.git" "(null)" "$here/21a/.git/wt/sub" "(null)" &&
-
-	setup_repo 21b non-existent "" true &&
-	mkdir -p 21b/.git/wt/sub &&
-	try_case 21b/.git non-existent-too unset \
-		. "(null)" "$here/21b/.git" "(null)" &&
-	try_case 21b/.git/wt non-existent-too unset \
-		"$here/21b/.git" "(null)" "$here/21b/.git/wt" "(null)" &&
-	try_case 21b/.git/wt/sub non-existent-too unset \
-		"$here/21b/.git" "(null)" "$here/21b/.git/wt/sub" "(null)" &&
-
-	try_repo 21c non-existent-too unset non-existent "" true \
-		.git "(null)" "$here/21c" "(null)" \
-		"$here/21c/.git" "(null)" "$here/21c/sub" "(null)"
+	(
+		cd 20b/.git &&
+		test_must_fail git symbolic-ref HEAD >/dev/null
+	) 2>message &&
+	grep "core.bare and core.worktree" message
+'
+
+# Case #21: core.worktree/GIT_WORK_TREE overrides core.bare' '
+test_expect_success '#21: setup, core.worktree warns before overriding core.bare' '
+	setup_repo 21 non-existent "" unset &&
+	mkdir -p 21/.git/wt/sub &&
+	(
+		cd 21/.git &&
+		GIT_WORK_TREE="$here/21" &&
+		export GIT_WORK_TREE &&
+		git symbolic-ref HEAD >/dev/null
+	) 2>message &&
+	! test -s message
+
 '
+run_wt_tests 21
 
 test_expect_success '#22a: core.worktree = GIT_DIR = .git dir' '
 	# like case #6.
@@ -699,10 +706,11 @@ test_expect_success '#24: bare repo has no worktree (gitfile case)' '
 		"$here/24.git" "(null)" "$here/24/sub" "(null)"
 '
 
-test_expect_success '#25: GIT_WORK_TREE ignored if GIT_DIR unset (bare gitfile case)' '
-	try_repo 25 non-existent unset unset gitfile true \
-		"$here/25.git" "(null)" "$here/25" "(null)" \
-		"$here/25.git" "(null)" "$here/25/sub" "(null)"
+test_expect_success '#25: GIT_WORK_TREE accepted if GIT_DIR unset (bare gitfile case)' '
+	try_repo 25 "$here/25" unset unset gitfile true \
+		"$here/25.git" "$here/25" "$here/25" "(null)"  \
+		"$here/25.git" "$here/25" "$here/25" "sub/" 2>message &&
+	! test -s message
 '
 
 test_expect_success '#26: bare repo has no worktree (GIT_DIR -> gitfile case)' '
@@ -721,17 +729,29 @@ test_expect_success '#27: setup' '
 '
 run_wt_tests 27 gitfile
 
-test_expect_success '#28: core.worktree ignored if GIT_DIR unset (bare gitfile case)' '
-	try_repo 28 unset unset non-existent gitfile true \
-		"$here/28.git" "(null)" "$here/28" "(null)" \
-		"$here/28.git" "(null)" "$here/28/sub" "(null)"
+test_expect_success '#28: core.worktree and core.bare conflict (gitfile case)' '
+	setup_repo 28 "$here/28" gitfile true &&
+	(
+		cd 28 &&
+		test_must_fail git symbolic-ref HEAD
+	) 2>message &&
+	! grep "^warning:" message &&
+	grep "core.bare and core.worktree" message
 '
 
-test_expect_success '#29: GIT_WORK_TREE+core.worktree ignored if GIT_DIR unset (bare gitfile case)' '
-	try_repo 29 non-existent-too unset non-existent gitfile true \
-		"$here/29.git" "(null)" "$here/29" "(null)" \
-		"$here/29.git" "(null)" "$here/29/sub" "(null)"
-'
+# Case #29: GIT_WORK_TREE(+core.worktree) overries core.bare (gitfile case).
+test_expect_success '#29: setup' '
+	setup_repo 29 non-existent gitfile true &&
+	mkdir -p 29/sub/sub 29/wt/sub
+	(
+		cd 29 &&
+		GIT_WORK_TREE="$here/29" &&
+		export GIT_WORK_TREE &&
+		git symbolic-ref HEAD >/dev/null
+	) 2>message &&
+	! test -s message
+'
+run_wt_tests 29 gitfile
 
 test_expect_success '#30: core.worktree and core.bare conflict (gitfile version)' '
 	# Just like case #22.