Merge branch 'nd/clone-linked-checkout' into maint

It was not possible to use a repository-lookalike created by "git
worktree add" as a local source of "git clone".

* nd/clone-linked-checkout:
  clone: better error when --reference is a linked checkout
  clone: allow --local from a linked checkout
  enter_repo: allow .git files in strict mode
  enter_repo: avoid duplicating logic, use is_git_directory() instead
  t0002: add test for enter_repo(), non-strict mode
  path.c: delete an extra space

builtin/clone.c

@@ -294,9 +294,14 @@ static int add_one_reference(struct string_list_item *item, void *cb_data)
 		char *ref_git_git = mkpathdup("%s/.git", ref_git);
 		free(ref_git);
 		ref_git = ref_git_git;
-	} else if (!is_directory(mkpath("%s/objects", ref_git)))
+	} else if (!is_directory(mkpath("%s/objects", ref_git))) {
+		struct strbuf sb = STRBUF_INIT;
+		if (get_common_dir(&sb, ref_git))
+			die(_("reference repository '%s' as a linked checkout is not supported yet."),
+			    item->string);
 		die(_("reference repository '%s' is not a local repository."),
 		    item->string);
+	}
 
 	if (!access(mkpath("%s/shallow", ref_git), F_OK))
 		die(_("reference repository '%s' is shallow"), item->string);
@@ -424,8 +429,10 @@ static void clone_local(const char *src_repo, const char *dest_repo)
 	} else {
 		struct strbuf src = STRBUF_INIT;
 		struct strbuf dest = STRBUF_INIT;
-		strbuf_addf(&src, "%s/objects", src_repo);
-		strbuf_addf(&dest, "%s/objects", dest_repo);
+		get_common_dir(&src, src_repo);
+		get_common_dir(&dest, dest_repo);
+		strbuf_addstr(&src, "/objects");
+		strbuf_addstr(&dest, "/objects");
 		copy_or_link_directory(&src, &dest, src_repo, src.len);
 		strbuf_release(&src);
 		strbuf_release(&dest);

path.c

@@ -445,18 +445,22 @@ const char *enter_repo(const char *path, int strict)
 		}
 		if (!suffix[i])
 			return NULL;
-		gitfile = read_gitfile(used_path) ;
+		gitfile = read_gitfile(used_path);
 		if (gitfile)
 			strcpy(used_path, gitfile);
 		if (chdir(used_path))
 			return NULL;
 		path = validated_path;
 	}
-	else if (chdir(path))
-		return NULL;
+	else {
+		const char *gitfile = read_gitfile(path);
+		if (gitfile)
+			path = gitfile;
+		if (chdir(path))
+			return NULL;
+	}
 
-	if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
-	    validate_headref("HEAD") == 0) {
+	if (is_git_directory(".")) {
 		set_git_dir(".");
 		check_repository_format();
 		return path;

t/t0002-gitfile.sh

@@ -116,4 +116,46 @@ test_expect_success 'setup_git_dir twice in subdir' '
 	)
 '
 
+test_expect_success 'enter_repo non-strict mode' '
+	test_create_repo enter_repo &&
+	(
+		cd enter_repo &&
+		test_tick &&
+		test_commit foo &&
+		mv .git .realgit &&
+		echo "gitdir: .realgit" >.git
+	) &&
+	git ls-remote enter_repo >actual &&
+	cat >expected <<-\EOF &&
+	946e985ab20de757ca5b872b16d64e92ff3803a9	HEAD
+	946e985ab20de757ca5b872b16d64e92ff3803a9	refs/heads/master
+	946e985ab20de757ca5b872b16d64e92ff3803a9	refs/tags/foo
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'enter_repo linked checkout' '
+	(
+		cd enter_repo &&
+		git worktree add  ../foo refs/tags/foo
+	) &&
+	git ls-remote foo >actual &&
+	cat >expected <<-\EOF &&
+	946e985ab20de757ca5b872b16d64e92ff3803a9	HEAD
+	946e985ab20de757ca5b872b16d64e92ff3803a9	refs/heads/master
+	946e985ab20de757ca5b872b16d64e92ff3803a9	refs/tags/foo
+	EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'enter_repo strict mode' '
+	git ls-remote --upload-pack="git upload-pack --strict" foo/.git >actual &&
+	cat >expected <<-\EOF &&
+	946e985ab20de757ca5b872b16d64e92ff3803a9	HEAD
+	946e985ab20de757ca5b872b16d64e92ff3803a9	refs/heads/master
+	946e985ab20de757ca5b872b16d64e92ff3803a9	refs/tags/foo
+	EOF
+	test_cmp expected actual
+'
+
 test_done

t/t2025-worktree-add.sh

@@ -193,4 +193,9 @@ test_expect_success '"add" -B/--detach mutually exclusive' '
 	test_must_fail git worktree add -B poodle --detach bamboo master
 '
 
+test_expect_success 'local clone from linked checkout' '
+	git clone --local here here-clone &&
+	( cd here-clone && git fsck )
+'
+
 test_done