[PATCH v4 6/6] clean: teach clean -d to skip dirs containing ignored files

[Samuel Lijin]

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).

This also fixes the known breakage in t7300 since clean -d now skips
untracked directories containing ignored files.

Signed-off-by: Samuel Lijin <sxli...@gmail.com>
---
 builtin/clean.c  | 38 +++++++++++++++++++++++++++++++++++++-
 t/t7300-clean.sh |  2 +-
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/builtin/clean.c b/builtin/clean.c
index d861f836a..0d490d76e 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, 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;
 
@@ -932,12 +935,39 @@ int cmd_clean(int argc, const char **argv, const char 
*prefix)
 
        fill_directory(&dir, &pathspec);
 
+       for (j = i = 0; i < dir.nr;) {
+               for (;
+                    j < dir.ignored_nr &&
+                      0 <= cmp_dir_entry(&dir.entries[i], &dir.ignored[j]);
+                    j++);
+
+               if ((j < dir.ignored_nr) &&
+                               check_dir_entry_contains(dir.entries[i], 
dir.ignored[j])) {
+                       /* skip any dir.entries which contains a dir.ignored */
+                       free(dir.entries[i]);
+                       dir.entries[i++] = NULL;
+               } else {
+                       /* prune the contents of a dir.entries which will be 
removed */
+                       struct dir_entry *ent = dir.entries[i++];
+                       for (;
+                            i < dir.nr &&
+                              check_dir_entry_contains(ent, dir.entries[i]);
+                            i++) {
+                               free(dir.entries[i]);
+                               dir.entries[i] = NULL;
+                       }
+               }
+       }
+
        for (i = 0; i < dir.nr; i++) {
                struct dir_entry *ent = dir.entries[i];
                int matches = 0;
                struct stat st;
                const char *rel;
 
+               if (!ent)
+                       continue;
+
                if (!cache_name_is_other(ent->name, ent->len))
                        continue;
 
@@ -958,6 +988,12 @@ int cmd_clean(int argc, const char **argv, const char 
*prefix)
                string_list_append(&del_list, rel);
        }
 
+       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();
 
diff --git a/t/t7300-clean.sh b/t/t7300-clean.sh
index 3a2d709c2..7b36954d6 100755
--- a/t/t7300-clean.sh
+++ b/t/t7300-clean.sh
@@ -653,7 +653,7 @@ test_expect_success 'git clean -d respects pathspecs 
(pathspec is prefix of dir)
        test_path_is_dir foobar
 '
 
-test_expect_failure 'git clean -d skips untracked dirs containing ignored 
files' '
+test_expect_success 'git clean -d skips untracked dirs containing ignored 
files' '
        echo /foo/bar >.gitignore &&
        echo ignoreme >>.gitignore &&
        rm -rf foo &&
-- 
2.13.0