fix unused variable error if no zstd

diff --git a/libarchive/archive_write_add_filter_zstd.c b/libarchive/archive_write_add_filter_zstd.c
index 37c5e741ebeee18545bd7f3a52ad8555158b7afe..f32258b460ebea8050e05658062fc6369b2b8555 100644 (file)
--- a/libarchive/archive_write_add_filter_zstd.c
+++ b/libarchive/archive_write_add_filter_zstd.c
@@ -451,6 +451,7 @@ archive_compressor_zstd_write(struct archive_write_filter *f, const void *buff,
 static int
 archive_compressor_zstd_flush(struct archive_write_filter *f)
 {
+       (void)f; /* UNUSED */
 
        return (ARCHIVE_OK);
 }