Silence warnings when tracing feature is disabled.

CHANGELOG.md

@@ -13,6 +13,9 @@
 - Added `SupervisorOptions` for Supervisor::start/start_link/child_spec.
 - Ability to customize the process name of the registry (use at own risk).
 
+### Fixed
+- Fixed warnings when tracing feature is disabled.
+
 # 0.1.18
 
 ### Added

hydra/src/application.rs

@@ -1,6 +1,5 @@
 use std::future::Future;
 
-use std::sync::Once;
 use std::time::Duration;
 
 use serde::Deserialize;
@@ -58,13 +57,16 @@ pub trait Application: Sized + Send + 'static {
 
         #[cfg(feature = "tracing")]
         if Self::TRACING_SUBSCRIBE {
+            use std::sync::Once;
+
             static TRACING_SUBSCRIBE_ONCE: Once = Once::new();
 
             TRACING_SUBSCRIBE_ONCE.call_once(|| {
                 tracing_subscriber::fmt::init();
             });
         }
 
+        #[allow(unused_mut)]
         let mut prev_hook: Option<_> = None;
 
         #[cfg(feature = "tracing")]

hydra/src/registry.rs

@@ -429,6 +429,9 @@ impl Registry {
         #[cfg(feature = "tracing")]
         tracing::info!(reason = ?reason, child_key = ?key, child_pid = ?pid, "Removed registered process");
 
+        #[cfg(not(feature = "tracing"))]
+        let _ = reason;
+
         REGISTRY.alter(&self.name, |_, value| {
             value.remove_if(&key, |_, value| *value == pid);
             value

hydra/src/supervisor.rs

@@ -335,6 +335,9 @@ impl Supervisor {
                     #[cfg(feature = "tracing")]
                     tracing::error!(reason = ?reason, child_id = ?self.children[index].spec.id, "Start error");
 
+                    #[cfg(not(feature = "tracing"))]
+                    let _ = reason;
+
                     return Err(ExitReason::from("failed_to_start_child"));
                 }
             }
@@ -559,6 +562,9 @@ impl Supervisor {
                         #[cfg(feature = "tracing")]
                         tracing::error!(reason = ?reason, child_id = ?id, child_pid = ?self.children[index].pid, "Start error");
 
+                        #[cfg(not(feature = "tracing"))]
+                        let _ = reason;
+
                         self.children[index].restarting = true;
 
                         Supervisor::cast(Process::current(), TryAgainRestartId(id));
@@ -572,6 +578,9 @@ impl Supervisor {
                     #[cfg(feature = "tracing")]
                     tracing::error!(reason = ?reason, child_id = ?id, child_pid = ?self.children[index].pid, "Start error");
 
+                    #[cfg(not(feature = "tracing"))]
+                    let _ = reason;
+
                     self.children[index].restarting = true;
 
                     Supervisor::cast(Process::current(), TryAgainRestartId(id));
@@ -584,6 +593,9 @@ impl Supervisor {
                     #[cfg(feature = "tracing")]
                     tracing::error!(reason = ?reason, child_id = ?id, child_pid = ?self.children[index].pid, "Start error");
 
+                    #[cfg(not(feature = "tracing"))]
+                    let _ = reason;
+
                     self.children[index].restarting = true;
 
                     Supervisor::cast(Process::current(), TryAgainRestartId(id));