pathspec: add flag to indicate operation without repository

A following change will add support for pathspecs to the git diff
--no-index command. This mode of git diff does not load any repository.

Add a new PATHSPEC_NO_REPOSITORY flag indicating that we're parsing
pathspecs without a repository.

Both PATHSPEC_ATTR and PATHSPEC_FROMTOP require a repository to
function. Thus, verify that both of these are set in magic_mask to
ensure they won't be accepted when PATHSPEC_NO_REPOSITORY is set.

Check PATHSPEC_NO_REPOSITORY when warning about paths outside the
directory tree. When the flag is set, do not look for a git repository
when generating the warning message.

Finally, add a BUG in match_pathspec_item if the istate is NULL but the
pathspec has PATHSPEC_ATTR set. Callers which support PATHSPEC_ATTR
should always pass a valid istate, and callers which don't pass a valid
istate should have set PATHSPEC_ATTR in the magic_mask field to disable
support for attribute-based pathspecs.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: jacob-keller

dir.c

@@ -397,9 +397,12 @@ static int match_pathspec_item(struct index_state *istate,
 	    strncmp(item->match, name - prefix, item->prefix))
 		return 0;
 
-	if (item->attr_match_nr &&
-	    !match_pathspec_attrs(istate, name - prefix, namelen + prefix, item))
-		return 0;
+	if (item->attr_match_nr) {
+		if (!istate)
+			BUG("magic PATHSPEC_ATTR requires an index");
+		if (!match_pathspec_attrs(istate, name - prefix, namelen + prefix, item))
+			return 0;
+	}
 
 	/* If the match was just the prefix, we matched */
 	if (!*match)

pathspec.c

@@ -492,7 +492,7 @@ static void init_pathspec_item(struct pathspec_item *item, unsigned flags,
 		if (!match) {
 			const char *hint_path;
 
-			if (!have_git_dir())
+			if ((flags & PATHSPEC_NO_REPOSITORY) || !have_git_dir())
 				die(_("'%s' is outside the directory tree"),
 				    copyfrom);
 			hint_path = repo_get_work_tree(the_repository);
@@ -614,6 +614,10 @@ void parse_pathspec(struct pathspec *pathspec,
 	    (flags & PATHSPEC_PREFER_FULL))
 		BUG("PATHSPEC_PREFER_CWD and PATHSPEC_PREFER_FULL are incompatible");
 
+	if ((flags & PATHSPEC_NO_REPOSITORY) &&
+	    (~magic_mask & (PATHSPEC_ATTR | PATHSPEC_FROMTOP)))
+		BUG("PATHSPEC_NO_REPOSITORY is incompatible with PATHSPEC_ATTR and PATHSPEC_FROMTOP");
+
 	/* No arguments with prefix -> prefix pathspec */
 	if (!entry) {
 		if (flags & PATHSPEC_PREFER_FULL)

pathspec.h

@@ -76,6 +76,11 @@ struct pathspec {
  * allowed, then it will automatically set for every pathspec.
  */
 #define PATHSPEC_LITERAL_PATH (1<<6)
+/*
+ * For git diff --no-index, indicate that we are operating without
+ * a repository or index.
+ */
+#define PATHSPEC_NO_REPOSITORY (1<<7)
 
 /**
  * Given command line arguments and a prefix, convert the input to