Merge branch 'pb/stash-refuse-to-kill'

"git stash save" is not just about "saving" the local changes, but
also is to restore the working tree state to that of HEAD. If you
changed a non-directory into a directory in the local change, you
may have untracked files in that directory, which have to be killed
while doing so, unless you run it with --include-untracked.  Teach
the command to detect and error out before spreading the damage.

This needed a small fix to "ls-files --killed".

* pb/stash-refuse-to-kill:
  git stash: avoid data loss when "git stash save" kills a directory
  treat_directory(): do not declare submodules to be untracked

Documentation/git-stash.txt

@@ -14,7 +14,8 @@ SYNOPSIS
 'git stash' ( pop | apply ) [--index] [-q|--quiet] [<stash>]
 'git stash' branch <branchname> [<stash>]
 'git stash' [save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
-	     [-u|--include-untracked] [-a|--all] [<message>]]
+	     [-u|--include-untracked] [-a|--all] [-f|--force]
+	     [<message>]]
 'git stash' clear
 'git stash' create [<message>]
 'git stash' store [-m|--message <message>] [-q|--quiet] <commit>
@@ -44,7 +45,7 @@ is also possible).
 OPTIONS
 -------
 
-save [-p|--patch] [--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [<message>]::
+save [-p|--patch] [--[no-]keep-index] [-u|--include-untracked] [-a|--all] [-q|--quiet] [-f|--force] [<message>]::
 
 	Save your local modifications to a new 'stash', and run `git reset
 	--hard` to revert them.  The <message> part is optional and gives
@@ -71,6 +72,13 @@ linkgit:git-add[1] to learn how to operate the `--patch` mode.
 +
 The `--patch` option implies `--keep-index`.  You can use
 `--no-keep-index` to override this.
++
+In some cases, saving a stash could mean irretrievably removing some
+data - if a directory with untracked files replaces a tracked file of
+the same name, the new untracked files are not saved (except in case
+of `--include-untracked`) but the original tracked file shall be restored.
+By default, `stash save` will abort in such a case; `--force` will allow
+it to remove the untracked files.
 
 list [<options>]::
 

dir.c

@@ -1036,9 +1036,7 @@ static enum path_treatment treat_directory(struct dir_struct *dir,
 		return path_recurse;
 
 	case index_gitdir:
-		if (dir->flags & DIR_SHOW_OTHER_DIRECTORIES)
-			return path_none;
-		return path_untracked;
+		return path_none;
 
 	case index_nonexistent:
 		if (dir->flags & DIR_SHOW_OTHER_DIRECTORIES)

git-stash.sh

@@ -195,6 +195,7 @@ save_stash () {
 	keep_index=
 	patch_mode=
 	untracked=
+	force=
 	while test $# != 0
 	do
 		case "$1" in
@@ -215,6 +216,9 @@ save_stash () {
 		-u|--include-untracked)
 			untracked=untracked
 			;;
+		-f|--force)
+			force=t
+			;;
 		-a|--all)
 			untracked=all
 			;;
@@ -258,6 +262,14 @@ save_stash () {
 		say "$(gettext "No local changes to save")"
 		exit 0
 	fi
+	if test -z "$untracked$force" &&
+	   test -n "$(git ls-files --killed | head -n 1)"
+	then
+		say "$(gettext "The following untracked files would NOT be saved but need to be removed by stash save:")"
+		test -n "$GIT_QUIET" || git ls-files --killed | sed 's/^/\t/'
+		say "$(gettext "Aborting. Consider using either the --force or --include-untracked option.")" >&2
+		exit 1
+	fi
 	test -f "$GIT_DIR/logs/$ref_stash" ||
 		clear_stash || die "$(gettext "Cannot initialize stash")"
 

t/t3010-ls-files-killed-modified.sh

@@ -11,6 +11,8 @@ This test prepares the following in the cache:
     path1       - a symlink
     path2/file2 - a file in a directory
     path3/file3 - a file in a directory
+    submod1/	- a submodule
+    submod2/	- another submodule
 
 and the following on the filesystem:
 
@@ -21,9 +23,11 @@ and the following on the filesystem:
     path4	- a file
     path5	- a symlink
     path6/file6 - a file in a directory
+    submod1/	- a submodule (modified from the cache)
+    submod2/	- a submodule (matches the cache)
 
-git ls-files -k should report that existing filesystem
-objects except path4, path5 and path6/file6 to be killed.
+git ls-files -k should report that existing filesystem objects
+path0/*, path1/*, path2 and path3 to be killed.
 
 Also for modification test, the cache and working tree have:
 
@@ -33,7 +37,7 @@ Also for modification test, the cache and working tree have:
     path10	- a non-empty file, cache dirtied.
 
 We should report path0, path1, path2/file2, path3/file3, path7 and path8
-modified without reporting path9 and path10.
+modified without reporting path9 and path10.  submod1 is also modified.
 '
 . ./test-lib.sh
 
@@ -48,6 +52,18 @@ test_expect_success 'git update-index --add to add various paths.' '
 	: >path9 &&
 	date >path10 &&
 	git update-index --add -- path0 path?/file? path7 path8 path9 path10 &&
+	for i in 1 2
+	do
+		git init submod$i &&
+		(
+			cd submod$i && git commit --allow-empty -m "empty $i"
+		) || break
+	done &&
+	git update-index --add submod[12]
+	(
+		cd submod1 &&
+		git commit --allow-empty -m "empty 1 (updated)"
+	) &&
 	rm -fr path?	# leave path10 alone
 '
 
@@ -94,6 +110,7 @@ test_expect_success 'validate git ls-files -m output.' '
 	path3/file3
 	path7
 	path8
+	submod1
 	EOF
 	test_cmp .expected .output
 '

t/t3903-stash.sh

@@ -673,4 +673,22 @@ test_expect_success 'store updates stash ref and reflog' '
 	grep quux bazzy
 '
 
+test_expect_success 'stash a change to turn a non-directory to a directory' '
+	git reset --hard &&
+	>testfile &&
+	git add testfile &&
+	git commit -m "add testfile as a regular file" &&
+	rm testfile &&
+	mkdir testfile &&
+	>testfile/file &&
+	test_must_fail git stash save "recover regular file" &&
+	test -f testfile/file
+'
+
+test_expect_success 'stash a change to turn a non-directory to a directory (forced)' '
+	git stash save --force "recover regular file (forced)" &&
+	! test -f testfile/file &&
+	test -f testfile
+'
+
 test_done