use replace value

logger/src/lib.rs

@@ -26,7 +26,7 @@ fn replace_logger(logger: env_logger::Logger) {
     let max_level = logger.filter();
     log::set_max_level(max_level);
     let mut rw = LOGGER.write().unwrap();
-    std::mem::replace(&mut *rw, logger);
+    let _ = std::mem::replace(&mut *rw, logger);
     let _ = log::set_boxed_logger(Box::new(LoggerShim {}));
 }
 

metrics/src/metrics.rs

@@ -334,7 +334,7 @@ lazy_static! {
 pub fn set_host_id(host_id: String) {
     let mut rw = HOST_ID.write().unwrap();
     info!("host id: {}", host_id);
-    std::mem::replace(&mut *rw, host_id);
+    let _ = std::mem::replace(&mut *rw, host_id);
 }
 
 /// Submits a new point from any thread.  Note that points are internally queued

programs/budget/src/budget_expr.rs

@@ -256,7 +256,7 @@ impl BudgetExpr {
             _ => None,
         };
         if let Some(expr) = new_expr {
-            mem::replace(self, *expr);
+            let _ = mem::replace(self, *expr);
         }
     }
 }