Bug: https://bugs.gentoo.org/594538

--- a/src/cache_logger.hh
+++ b/src/cache_logger.hh
@@ -23,7 +23,7 @@
   // if given the empty filename, do nothing
   explicit cache_logger(std::string const & filename, int max_size);
 
-  bool logging() const { return _impl; }
+  bool logging() const { return static_cast<bool>(_impl); }
 
   void log_exists(bool exists, int position, int item_count, int est_size) const;
   void log_touch(bool exists, int position, int item_count, int est_size) const;
--- a/src/cmd_ws_commit.cc
+++ b/src/cmd_ws_commit.cc
@@ -1170,7 +1170,7 @@
     {
       for (attr_map_t::iterator i = node->attrs.begin();
            i != node->attrs.end(); ++i)
-        i->second = make_pair(false, "");
+        i->second = make_pair(false, attr_value(""));
     }
   else
     {
@@ -1179,7 +1179,7 @@
       E(node->attrs.find(a_key) != node->attrs.end(), origin::user,
         F("path '%s' does not have attribute '%s'")
         % path % a_key);
-      node->attrs[a_key] = make_pair(false, "");
+      node->attrs[a_key] = make_pair(false, attr_value(""));
     }
 
   cset cs;
--- a/src/roster.cc
+++ b/src/roster.cc
@@ -223,7 +223,7 @@
 
 bool marking_map::contains(node_id nid) const
 {
-  return _store.get_if_present(nid);
+  return static_cast<bool>(_store.get_if_present(nid));
 }
 
 void marking_map::remove_marking(node_id nid)
@@ -727,7 +727,7 @@
 bool
 roster_t::has_node(node_id n) const
 {
-  return nodes.get_if_present(n);
+  return static_cast<bool>(nodes.get_if_present(n));
 }
 
 bool
@@ -1898,8 +1898,8 @@
       node_t const &left_node = left_roster.all_nodes().get_if_present(i->first);
       node_t const &right_node = right_roster.all_nodes().get_if_present(i->first);
 
-      bool exists_in_left = (left_node);
-      bool exists_in_right = (right_node);
+      bool exists_in_left = static_cast<bool>(left_node);
+      bool exists_in_right = static_cast<bool>(right_node);
 
       if (!exists_in_left && !exists_in_right)
         mark_new_node(new_rid, n, new_markings);