commit 3bbebbb29f6fbbf2988b9f2e75695b7c0b1f1c9b
Author: Andreas Gruenbacher <agruen@gnu.org>
Date:   Wed Feb 7 12:01:22 2018 +0100

    Avoid set_file_attributes sign conversion warnings
    
    * src/util.c (set_file_attributes): Avoid sign conversion warnings when
    assigning -1 to uid_t / gid_t.

diff --git a/src/util.c b/src/util.c
index b1c7266..1cc08ba 100644
--- a/src/util.c
+++ b/src/util.c
@@ -256,8 +256,8 @@ set_file_attributes (char const *to, enum file_attributes attr,
     }
   if (attr & FA_IDS)
     {
-      static uid_t euid = -1;
-      static gid_t egid = -1;
+      static uid_t euid = (uid_t)-1;
+      static gid_t egid = (gid_t)-1;
       uid_t uid;
       uid_t gid;