[PATCH v3 6/8] clean: teach clean -d to skip dirs containing ignored files

[Samuel Lijin <sxlijin@gmail.com>]

There is an implicit assumption that a directory containing only
untracked and ignored files should itself be considered untracked. This
makes sense in use cases where we're asking if a directory should be
added to the git database, but not when we're asking if a directory can
be safely removed from the working tree; as a result, clean -d would
assume that an "untracked" directory containing ignored files could be
deleted.

To get around this, we teach clean -d to collect ignored files and skip
over so-called "untracked" directories if they contain any ignored
files (while still removing the untracked contents of such dirs).

Signed-off-by: Samuel Lijin <sxlijin@gmail.com>
---
 builtin/clean.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/builtin/clean.c b/builtin/clean.c
index d861f836a..25f3efce5 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -859,7 +859,7 @@ static void interactive_main_loop(void)
 
 int cmd_clean(int argc, const char **argv, const char *prefix)
 {
-	int i, res;
+	int i, j, k, res;
 	int dry_run = 0, remove_directories = 0, quiet = 0, ignored = 0;
 	int ignored_only = 0, config_set = 0, errors = 0, gone = 1;
 	int rm_flags = REMOVE_DIR_KEEP_NESTED_GIT;
@@ -911,6 +911,9 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 				  " refusing to clean"));
 	}
 
+	if (remove_directories)
+		dir.flags |= DIR_SHOW_IGNORED_TOO | DIR_KEEP_UNTRACKED_CONTENTS;
+
 	if (force > 1)
 		rm_flags = 0;
 
@@ -932,7 +935,7 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 
 	fill_directory(&dir, &pathspec);
 
-	for (i = 0; i < dir.nr; i++) {
+	for (k = i = 0; i < dir.nr; i++) {
 		struct dir_entry *ent = dir.entries[i];
 		int matches = 0;
 		struct stat st;
@@ -954,10 +957,35 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 		    matches != MATCHED_EXACTLY)
 			continue;
 
+		// skip any dir.entries which contains a dir.ignored
+		for (; k < dir.ignored_nr; k++) {
+			if (cmp_dir_entry(&dir.entries[i],
+						&dir.ignored[k]) < 0)
+				break;
+		}
+		if ((k < dir.ignored_nr) &&
+				check_dir_entry_contains(dir.entries[i], dir.ignored[k])) {
+			continue;
+		}
+
+		// current entry does not contain any ignored files
 		rel = relative_path(ent->name, prefix, &buf);
 		string_list_append(&del_list, rel);
+
+		// skip untracked contents of an untracked dir
+		for (j = i + 1;
+			 j < dir.nr &&
+			     check_dir_entry_contains(dir.entries[i], dir.entries[j]);
+			 j++);
+		i = j - 1;
 	}
 
+	for (i = 0; i < dir.nr; i++)
+		free(dir.entries[i]);
+
+	for (i = 0; i < dir.ignored_nr; i++)
+		free(dir.ignored[i]);
+
 	if (interactive && del_list.nr > 0)
 		interactive_main_loop();
 
-- 
2.12.2