parse_pathspec: add PATHSPEC_PREFER_{CWD,FULL} flags

We have two ways of dealing with empty pathspec:

1. limit it to current prefix
2. match the entire working directory

Some commands go with #1, some #2. get_pathspec() and parse_pathspec()
only support #1. Make parse_pathspec() reject empty pathspec by
default. #1 and #2 can be specified via new flags. This makes it more
expressive about default behavior at command level.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pathspec.c

@@ -271,10 +271,20 @@ void parse_pathspec(struct pathspec *pathspec,
 	if (!entry && !prefix)
 		return;
 
+	if ((flags & PATHSPEC_PREFER_CWD) &&
+	    (flags & PATHSPEC_PREFER_FULL))
+		die("BUG: PATHSPEC_PREFER_CWD and PATHSPEC_PREFER_FULL are incompatible");
+
 	/* No arguments with prefix -> prefix pathspec */
 	if (!entry) {
 		static const char *raw[2];
 
+		if (flags & PATHSPEC_PREFER_FULL)
+			return;
+
+		if (!(flags & PATHSPEC_PREFER_CWD))
+			die("BUG: PATHSPEC_PREFER_CWD requires arguments");
+
 		pathspec->items = item = xmalloc(sizeof(*item));
 		memset(item, 0, sizeof(*item));
 		item->match = prefix;
@@ -340,7 +350,8 @@ const char **get_pathspec(const char *prefix, const char **pathspec)
 	struct pathspec ps;
 	parse_pathspec(&ps,
 		       PATHSPEC_ALL_MAGIC & ~PATHSPEC_FROMTOP,
-		       0, prefix, pathspec);
+		       PATHSPEC_PREFER_CWD,
+		       prefix, pathspec);
 	return ps.raw;
 }
 

pathspec.h

@@ -24,6 +24,10 @@ struct pathspec {
 	} *items;
 };
 
+/* parse_pathspec flags */
+#define PATHSPEC_PREFER_CWD (1<<0) /* No args means match cwd */
+#define PATHSPEC_PREFER_FULL (1<<1) /* No args means match everything */
+
 extern int init_pathspec(struct pathspec *, const char **);
 extern void parse_pathspec(struct pathspec *pathspec,
 			   unsigned magic_mask,