sparse-checkout: add --verbose option to 'clean'

The 'git sparse-checkout clean' subcommand is focused on directories,
deleting any tracked sparse directories to clean up the worktree and
make the sparse index feature work optimally.

However, this directory-focused approach can leave users wondering why
those directories exist at all. In my experience, these files are left
over due to ignore or exclude patterns, Windows file handles, or
possibly merge conflict resolutions.

Add a new '--verbose' option for users to see all the files that are
being deleted (with '--force') or would be deleted (with '--dry-run').

Based on usage, users may request further context on this list of files for
states such as tracked/untracked, unstaged/staged/conflicted, etc.

Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-sparse-checkout.adoc

@@ -136,6 +136,11 @@ The `--dry-run` option will list the directories that would be removed
 without deleting them. Running in this mode can be helpful to predict the
 behavior of the clean comand or to determine which kinds of files are left
 in the sparse directories.
++
+The `--verbose` option will list every file within the directories that
+are considered for removal. This option is helpful to determine if those
+files are actually important or perhaps to explain why the directory is
+still present despite the current sparse-checkout.
 
 'disable'::
 	Disable the `core.sparseCheckout` config setting, and restore the

builtin/sparse-checkout.c

@@ -930,6 +930,24 @@ static char const * const builtin_sparse_checkout_clean_usage[] = {
 	NULL
 };
 
+static int list_file_iterator(const char *path, const void *data)
+{
+	const char *msg = data;
+
+	printf(msg, path);
+	return 0;
+}
+
+static void list_every_file_in_dir(const char *msg,
+				   const char *directory)
+{
+	struct strbuf path = STRBUF_INIT;
+
+	strbuf_addstr(&path, directory);
+	for_each_file_in_dir(&path, list_file_iterator, msg);
+	strbuf_release(&path);
+}
+
 static const char *msg_remove = N_("Removing %s\n");
 static const char *msg_would_remove = N_("Would remove %s\n");
 
@@ -940,12 +958,13 @@ static int sparse_checkout_clean(int argc, const char **argv,
 	struct strbuf full_path = STRBUF_INIT;
 	const char *msg = msg_remove;
 	size_t worktree_len;
-	int force = 0, dry_run = 0;
+	int force = 0, dry_run = 0, verbose = 0;
 	int require_force = 1;
 
 	struct option builtin_sparse_checkout_clean_options[] = {
 		OPT__DRY_RUN(&dry_run, N_("dry run")),
 		OPT__FORCE(&force, N_("force"), PARSE_OPT_NOCOMPLETE),
+		OPT__VERBOSE(&verbose, N_("report each affected file, not just directories")),
 		OPT_END(),
 	};
 
@@ -987,7 +1006,10 @@ static int sparse_checkout_clean(int argc, const char **argv,
 		if (!is_directory(full_path.buf))
 			continue;
 
-		printf(msg, ce->name);
+		if (verbose)
+			list_every_file_in_dir(msg, ce->name);
+		else
+			printf(msg, ce->name);
 
 		if (dry_run <= 0 &&
 		    remove_dir_recursively(&full_path, 0))

t/t1091-sparse-checkout-builtin.sh

@@ -1053,11 +1053,11 @@ test_expect_success 'check-rules null termination' '
 test_expect_success 'clean' '
 	git -C repo sparse-checkout set --cone deep/deeper1 &&
 	git -C repo sparse-checkout reapply &&
-	mkdir repo/deep/deeper2 repo/folder1 &&
+	mkdir -p repo/deep/deeper2 repo/folder1/extra/inside &&
 
 	# Add untracked files
 	touch repo/deep/deeper2/file &&
-	touch repo/folder1/file &&
+	touch repo/folder1/extra/inside/file &&
 
 	test_must_fail git -C repo sparse-checkout clean 2>err &&
 	grep "refusing to clean" err &&
@@ -1074,7 +1074,15 @@ test_expect_success 'clean' '
 	git -C repo sparse-checkout clean --dry-run >out &&
 	test_cmp expect out &&
 	test_path_exists repo/deep/deeper2 &&
-	test_path_exists repo/folder1 &&
+	test_path_exists repo/folder1/extra/inside/file &&
+
+	cat >expect <<-\EOF &&
+	Would remove deep/deeper2/file
+	Would remove folder1/extra/inside/file
+	EOF
+
+	git -C repo sparse-checkout clean --dry-run --verbose >out &&
+	test_cmp expect out &&
 
 	cat >expect <<-\EOF &&
 	Removing deep/deeper2/