Merge branch 'en/keep-cwd'

Many git commands that deal with working tree files try to remove a
directory that becomes empty (i.e. "git switch" from a branch that
has the directory to another branch that does not would attempt
remove all files in the directory and the directory itself).  This
drops users into an unfamiliar situation if the command was run in
a subdirectory that becomes subject to removal due to the command.
The commands have been taught to keep an empty directory if it is
the directory they were started in to avoid surprising users.

* en/keep-cwd:
  t2501: simplify the tests since we can now assume desired behavior
  dir: new flag to remove_dir_recurse() to spare the original_cwd
  dir: avoid incidentally removing the original_cwd in remove_path()
  stash: do not attempt to remove startup_info->original_cwd
  rebase: do not attempt to remove startup_info->original_cwd
  clean: do not attempt to remove startup_info->original_cwd
  symlinks: do not include startup_info->original_cwd in dir removal
  unpack-trees: add special cwd handling
  unpack-trees: refuse to remove startup_info->original_cwd
  setup: introduce startup_info->original_cwd
  t2501: add various tests for removing the current working directory

3 files changed, 40 insertions, 11 deletions

diff --git a/builtin/clean.c b/builtin/clean.c
index 98a2860409..3ff02bbbff 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -36,6 +36,8 @@ static const char *msg_skip_git_dir = N_("Skipping repository %s\n");
 static const char *msg_would_skip_git_dir = N_("Would skip repository %s\n");
 static const char *msg_warn_remove_failed = N_("failed to remove %s");
 static const char *msg_warn_lstat_failed = N_("could not lstat %s\n");
+static const char *msg_skip_cwd = N_("Refusing to remove current working directory\n");
+static const char *msg_would_skip_cwd = N_("Would refuse to remove current working directory\n");
 
 enum color_clean {
 	CLEAN_COLOR_RESET = 0,
@@ -153,6 +155,8 @@ static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag,
 {
 	DIR *dir;
 	struct strbuf quoted = STRBUF_INIT;
+	struct strbuf realpath = STRBUF_INIT;
+	struct strbuf real_ocwd = STRBUF_INIT;
 	struct dirent *e;
 	int res = 0, ret = 0, gone = 1, original_len = path->len, len;
 	struct string_list dels = STRING_LIST_INIT_DUP;
@@ -231,16 +235,36 @@ static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag,
 	strbuf_setlen(path, original_len);
 
 	if (*dir_gone) {
-		res = dry_run ? 0 : rmdir(path->buf);
-		if (!res)
-			*dir_gone = 1;
-		else {
-			int saved_errno = errno;
-			quote_path(path->buf, prefix, &quoted, 0);
-			errno = saved_errno;
-			warning_errno(_(msg_warn_remove_failed), quoted.buf);
+		/*
+		 * Normalize path components in path->buf, e.g. change '\' to
+		 * '/' on Windows.
+		 */
+		strbuf_realpath(&realpath, path->buf, 1);
+
+		/*
+		 * path and realpath are absolute; for comparison, we would
+		 * like to transform startup_info->original_cwd to an absolute
+		 * path too.
+		 */
+		 if (startup_info->original_cwd)
+			 strbuf_realpath(&real_ocwd,
+					 startup_info->original_cwd, 1);
+
+		if (!strbuf_cmp(&realpath, &real_ocwd)) {
+			printf("%s", dry_run ? _(msg_would_skip_cwd) : _(msg_skip_cwd));
 			*dir_gone = 0;
-			ret = 1;
+		} else {
+			res = dry_run ? 0 : rmdir(path->buf);
+			if (!res)
+				*dir_gone = 1;
+			else {
+				int saved_errno = errno;
+				quote_path(path->buf, prefix, &quoted, 0);
+				errno = saved_errno;
+				warning_errno(_(msg_warn_remove_failed), quoted.buf);
+				*dir_gone = 0;
+				ret = 1;
+			}
 		}
 	}
 
@@ -250,6 +274,8 @@ static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag,
 			printf(dry_run ?  _(msg_would_remove) : _(msg_remove), dels.items[i].string);
 	}
 out:
+	strbuf_release(&realpath);
+	strbuf_release(&real_ocwd);
 	strbuf_release(&quoted);
 	string_list_clear(&dels, 0);
 	return ret;
diff --git a/builtin/rm.c b/builtin/rm.c
index 3d0967cdc1..b4132e5d8e 100644
--- a/builtin/rm.c
+++ b/builtin/rm.c
@@ -399,12 +399,13 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 	if (!index_only) {
 		int removed = 0, gitmodules_modified = 0;
 		struct strbuf buf = STRBUF_INIT;
+		int flag = force ? REMOVE_DIR_PURGE_ORIGINAL_CWD : 0;
 		for (i = 0; i < list.nr; i++) {
 			const char *path = list.entry[i].name;
 			if (list.entry[i].is_submodule) {
 				strbuf_reset(&buf);
 				strbuf_addstr(&buf, path);
-				if (remove_dir_recursively(&buf, 0))
+				if (remove_dir_recursively(&buf, flag))
 					die(_("could not remove '%s'"), path);
 
 				removed = 1;
diff --git a/builtin/stash.c b/builtin/stash.c
index 18c812bbe0..fb1e466e5d 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -1538,8 +1538,10 @@ static int do_push_stash(const struct pathspec *ps, const char *stash_msg, int q
 			struct child_process cp = CHILD_PROCESS_INIT;
 
 			cp.git_cmd = 1;
+			if (startup_info->original_cwd)
+				cp.dir = startup_info->original_cwd;
 			strvec_pushl(&cp.args, "clean", "--force",
-				     "--quiet", "-d", NULL);
+				     "--quiet", "-d", ":/", NULL);
 			if (include_untracked == INCLUDE_ALL_FILES)
 				strvec_push(&cp.args, "-x");
 			if (run_command(&cp)) {