mv: let 'git mv file no-such-dir/' error out

Git used to trim the trailing slash, and make the command equivalent
to 'git mv file no-such-dir', which created the file no-such-dir
(while the trailing slash explicitly stated that it could only be a
directory).

This patch skips the trailing slash removal for the destination
path.  The path with its trailing slash is passed to rename(2),
which errors out with the appropriate message:

  $ git mv file no-such-dir/
  fatal: renaming 'file' failed: Not a directory

Original-patch-by: Duy Nguyen <pclouds@gmail.com>
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/mv.c

@@ -16,9 +16,12 @@ static const char * const builtin_mv_usage[] = {
 	NULL
 };
 
+#define DUP_BASENAME 1
+#define KEEP_TRAILING_SLASH 2
+
 static const char **internal_copy_pathspec(const char *prefix,
 					   const char **pathspec,
-					   int count, int base_name)
+					   int count, unsigned flags)
 {
 	int i;
 	const char **result = xmalloc((count + 1) * sizeof(const char *));
@@ -27,11 +30,12 @@ static const char **internal_copy_pathspec(const char *prefix,
 	for (i = 0; i < count; i++) {
 		int length = strlen(result[i]);
 		int to_copy = length;
-		while (to_copy > 0 && is_dir_sep(result[i][to_copy - 1]))
+		while (!(flags & KEEP_TRAILING_SLASH) &&
+		       to_copy > 0 && is_dir_sep(result[i][to_copy - 1]))
 			to_copy--;
-		if (to_copy != length || base_name) {
+		if (to_copy != length || flags & DUP_BASENAME) {
 			char *it = xmemdupz(result[i], to_copy);
-			if (base_name) {
+			if (flags & DUP_BASENAME) {
 				result[i] = xstrdup(basename(it));
 				free(it);
 			} else
@@ -87,16 +91,21 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 
 	source = internal_copy_pathspec(prefix, argv, argc, 0);
 	modes = xcalloc(argc, sizeof(enum update_mode));
-	dest_path = internal_copy_pathspec(prefix, argv + argc, 1, 0);
+	/*
+	 * Keep trailing slash, needed to let
+	 * "git mv file no-such-dir/" error out.
+	 */
+	dest_path = internal_copy_pathspec(prefix, argv + argc, 1,
+					   KEEP_TRAILING_SLASH);
 	submodule_gitfile = xcalloc(argc, sizeof(char *));
 
 	if (dest_path[0][0] == '\0')
 		/* special case: "." was normalized to "" */
-		destination = internal_copy_pathspec(dest_path[0], argv, argc, 1);
+		destination = internal_copy_pathspec(dest_path[0], argv, argc, DUP_BASENAME);
 	else if (!lstat(dest_path[0], &st) &&
 			S_ISDIR(st.st_mode)) {
 		dest_path[0] = add_slash(dest_path[0]);
-		destination = internal_copy_pathspec(dest_path[0], argv, argc, 1);
+		destination = internal_copy_pathspec(dest_path[0], argv, argc, DUP_BASENAME);
 	} else {
 		if (argc != 1)
 			die("destination '%s' is not a directory", dest_path[0]);

t/t7001-mv.sh

@@ -70,6 +70,35 @@ test_expect_success \
 rm -f idontexist untracked1 untracked2 \
      path0/idontexist path0/untracked1 path0/untracked2 \
      .git/index.lock
+rmdir path1
+
+test_expect_success \
+    'moving to absent target with trailing slash' \
+    'test_must_fail git mv path0/COPYING no-such-dir/ &&
+     test_must_fail git mv path0/COPYING no-such-dir// &&
+     git mv path0/ no-such-dir/ &&
+     test_path_is_dir no-such-dir'
+
+test_expect_success \
+    'clean up' \
+    'git reset --hard'
+
+test_expect_success \
+    'moving to existing untracked target with trailing slash' \
+    'mkdir path1 &&
+     git mv path0/ path1/ &&
+     test_path_is_dir path1/path0/'
+
+test_expect_success \
+    'moving to existing tracked target with trailing slash' \
+    'mkdir path2 &&
+     >path2/file && git add path2/file &&
+     git mv path1/path0/ path2/ &&
+     test_path_is_dir path2/path0/'
+
+test_expect_success \
+    'clean up' \
+    'git reset --hard'
 
 test_expect_success \
     'adding another file' \