stash: allow "git stash -p <pathspec>" to assume push again

Historically "git stash [<options>]" was assumed to mean "git stash save
[<options>]". Since 1ada502 (stash: use stash_push for no verb form,
2017-02-28) it is assumed to mean "git stash push [<options>]". As the
push subcommand supports pathspecs 9e14090 (stash: allow pathspecs
in the no verb form, 2017-02-28) allowed "git stash -p <pathspec>" to
mean "git stash push -p <pathspec>". This was broken in
8c3713c (stash: eliminate crude option parsing, 2020-02-17) which
failed to account for "push" being added to the start of argv in
cmd_stash() before it calls push_stash() and kept looking in argv[0] for
"-p" after moving the code to push_stash().

The support for assuming "push" when "-p" is given introduced in
9e14090 is very narrow, neither "git stash -m <message> -p
<pathspec>" nor "git stash --patch <pathspec>" imply "push" and die
instead. Fix the regression introduced by 8c3713c and relax the
behavior introduced in 9e14090 by passing
PARSE_OPT_STOP_AT_NON_OPTION when push is being assumed and then setting
"force_assume" if "--patch" was present. This means "git stash
<pathspec> -p" still dies so do assume the user meant "push" if they
mistype a subcommand name but "git stash -m <message> -p <pathspec>"
will now succeed. Tests are added to prevent future regressions.

Signed-off-by: Phillip Wood <[email protected]>

Author: phillipwood

builtin/stash.c

@@ -1789,11 +1789,15 @@ static int push_stash(int argc, const char **argv, const char *prefix,
 	int ret;
 
 	if (argc) {
-		force_assume = !strcmp(argv[0], "-p");
+		int flags = PARSE_OPT_KEEP_DASHDASH;
+
+		if (push_assumed)
+			flags |= PARSE_OPT_STOP_AT_NON_OPTION;
+
 		argc = parse_options(argc, argv, prefix, options,
 				     push_assumed ? git_stash_usage :
-				     git_stash_push_usage,
-				     PARSE_OPT_KEEP_DASHDASH);
+				     git_stash_push_usage, flags);
+		force_assume |= patch_mode;
 	}
 
 	if (argc) {

t/t3903-stash.sh

@@ -1177,6 +1177,25 @@ test_expect_success 'stash -- <pathspec> stashes and restores the file' '
 	test_path_is_file bar
 '
 
+test_expect_success 'stash --patch <pathspec> stash and restores the file' '
+	cat file >expect-file &&
+	echo changed-file >file &&
+	echo changed-other-file >other-file &&
+	echo a | git stash -m "stash bar" --patch file &&
+	test_cmp expect-file file &&
+	echo changed-other-file >expect &&
+	test_cmp expect other-file &&
+	git stash pop &&
+	test_cmp expect other-file &&
+	echo changed-file >expect &&
+	test_cmp expect file
+'
+
+test_expect_success 'stash <pathspec> -p is rejected' '
+	test_must_fail git stash file -p 2>err &&
+	test_grep "subcommand wasn${SQ}t specified; ${SQ}push${SQ} can${SQ}t be assumed due to unexpected token ${SQ}file${SQ}" err
+'
+
 test_expect_success 'stash -- <pathspec> stashes in subdirectory' '
 	mkdir sub &&
 	>foo &&