Fix new compilation warnings in `debug_sync` module

diff --git a/lightning/src/debug_sync.rs b/lightning/src/debug_sync.rs
index daec309e9b5e35f81684ef9cdc5ed1df2be9e55c..b7466776a6e70f0f7720fdcadd3ade48a945089c 100644 (file)
--- a/lightning/src/debug_sync.rs
+++ b/lightning/src/debug_sync.rs
@@ -68,7 +68,8 @@ struct LockMetadata {
 
 struct LockDep {
        lock: Arc<LockMetadata>,
-       lockdep_trace: Backtrace,
+       /// lockdep_trace is unused unless we're building with `backtrace`, so we mark it _
+       _lockdep_trace: Backtrace,
 }
 
 #[cfg(feature = "backtrace")]
@@ -140,13 +141,13 @@ impl LockMetadata {
                                        // of the same lock.
                                        debug_assert!(cfg!(feature = "backtrace"), "Tried to acquire a lock while it was held!");
                                }
-                               for (locked_dep_idx, locked_dep) in locked.locked_before.lock().unwrap().iter() {
+                               for (locked_dep_idx, _locked_dep) in locked.locked_before.lock().unwrap().iter() {
                                        if *locked_dep_idx == this.lock_idx && *locked_dep_idx != locked.lock_idx {
                                                #[cfg(feature = "backtrace")]
                                                panic!("Tried to violate existing lockorder.\nMutex that should be locked after the current lock was created at the following backtrace.\nNote that to get a backtrace for the lockorder violation, you should set RUST_BACKTRACE=1\nLock being taken constructed at: {} ({}):\n{:?}\nLock constructed at: {} ({})\n{:?}\n\nLock dep created at:\n{:?}\n\n",
                                                        get_construction_location(&this._lock_construction_bt), this.lock_idx, this._lock_construction_bt,
                                                        get_construction_location(&locked._lock_construction_bt), locked.lock_idx, locked._lock_construction_bt,
-                                                       locked_dep.lockdep_trace);
+                                                       _locked_dep._lockdep_trace);
                                                #[cfg(not(feature = "backtrace"))]
                                                panic!("Tried to violate existing lockorder. Build with the backtrace feature for more info.");
                                        }
@@ -154,7 +155,7 @@ impl LockMetadata {
                                // Insert any already-held locks in our locked-before set.
                                let mut locked_before = this.locked_before.lock().unwrap();
                                if !locked_before.contains_key(&locked.lock_idx) {
-                                       let lockdep = LockDep { lock: Arc::clone(locked), lockdep_trace: Backtrace::new() };
+                                       let lockdep = LockDep { lock: Arc::clone(locked), _lockdep_trace: Backtrace::new() };
                                        locked_before.insert(lockdep.lock.lock_idx, lockdep);
                                }
                        }
@@ -175,7 +176,7 @@ impl LockMetadata {
                        let mut locked_before = this.locked_before.lock().unwrap();
                        for (locked_idx, locked) in held.borrow().iter() {
                                if !locked_before.contains_key(locked_idx) {
-                                       let lockdep = LockDep { lock: Arc::clone(locked), lockdep_trace: Backtrace::new() };
+                                       let lockdep = LockDep { lock: Arc::clone(locked), _lockdep_trace: Backtrace::new() };
                                        locked_before.insert(*locked_idx, lockdep);
                                }
                        }