Remove unnecessary mut from reference

chain::Listen's interface is defined in terms of non-mutable references,
so there's no need to use mutable references in lightning-block-sync.

diff --git a/lightning-block-sync/src/init.rs b/lightning-block-sync/src/init.rs
index 0bdc2a0255b85d4e902fc90e7c8924bf7d3990d7..c0e37ac0b9dadf809365b012c9d195f6dcda57b1 100644 (file)
--- a/lightning-block-sync/src/init.rs
+++ b/lightning-block-sync/src/init.rs
@@ -101,8 +101,8 @@ BlockSourceResult<ValidatedBlockHeader> {
 ///    let mut cache = UnboundedCache::new();
 ///    let mut monitor_listener = (monitor, &*tx_broadcaster, &*fee_estimator, &*logger);
 ///    let listeners = vec![
-///            (monitor_block_hash, &mut monitor_listener as &mut dyn chain::Listen),
-///            (manager_block_hash, &mut manager as &mut dyn chain::Listen),
+///            (monitor_block_hash, &monitor_listener as &dyn chain::Listen),
+///            (manager_block_hash, &manager as &dyn chain::Listen),
 ///    ];
 ///    let chain_tip = init::synchronize_listeners(
 ///            block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
@@ -125,7 +125,7 @@ pub async fn synchronize_listeners<B: BlockSource, C: Cache>(
        block_source: &mut B,
        network: Network,
        header_cache: &mut C,
-       mut chain_listeners: Vec<(BlockHash, &mut dyn chain::Listen)>,
+       mut chain_listeners: Vec<(BlockHash, &dyn chain::Listen)>,
 ) -> BlockSourceResult<ValidatedBlockHeader> {
        let best_header = validate_best_block_header(block_source).await?;
 
@@ -198,7 +198,7 @@ impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
 }
 
 /// Wrapper for supporting dynamically sized chain listeners.
-struct DynamicChainListener<'a>(&'a mut dyn chain::Listen);
+struct DynamicChainListener<'a>(&'a dyn chain::Listen);
 
 impl<'a> chain::Listen for DynamicChainListener<'a> {
        fn block_connected(&self, _block: &Block, _height: u32) {
@@ -211,7 +211,7 @@ impl<'a> chain::Listen for DynamicChainListener<'a> {
 }
 
 /// A set of dynamically sized chain listeners, each paired with a starting block height.
-struct ChainListenerSet<'a>(Vec<(u32, &'a mut dyn chain::Listen)>);
+struct ChainListenerSet<'a>(Vec<(u32, &'a dyn chain::Listen)>);
 
 impl<'a> chain::Listen for ChainListenerSet<'a> {
        fn block_connected(&self, block: &Block, height: u32) {
@@ -238,20 +238,20 @@ mod tests {
        async fn sync_from_same_chain() {
                let mut chain = Blockchain::default().with_height(4);
 
-               let mut listener_1 = MockChainListener::new()
+               let listener_1 = MockChainListener::new()
                        .expect_block_connected(*chain.at_height(2))
                        .expect_block_connected(*chain.at_height(3))
                        .expect_block_connected(*chain.at_height(4));
-               let mut listener_2 = MockChainListener::new()
+               let listener_2 = MockChainListener::new()
                        .expect_block_connected(*chain.at_height(3))
                        .expect_block_connected(*chain.at_height(4));
-               let mut listener_3 = MockChainListener::new()
+               let listener_3 = MockChainListener::new()
                        .expect_block_connected(*chain.at_height(4));
 
                let listeners = vec![
-                       (chain.at_height(1).block_hash, &mut listener_1 as &mut dyn chain::Listen),
-                       (chain.at_height(2).block_hash, &mut listener_2 as &mut dyn chain::Listen),
-                       (chain.at_height(3).block_hash, &mut listener_3 as &mut dyn chain::Listen),
+                       (chain.at_height(1).block_hash, &listener_1 as &dyn chain::Listen),
+                       (chain.at_height(2).block_hash, &listener_2 as &dyn chain::Listen),
+                       (chain.at_height(3).block_hash, &listener_3 as &dyn chain::Listen),
                ];
                let mut cache = chain.header_cache(0..=4);
                match synchronize_listeners(&mut chain, Network::Bitcoin, &mut cache, listeners).await {
@@ -267,26 +267,26 @@ mod tests {
                let fork_chain_2 = main_chain.fork_at_height(2);
                let fork_chain_3 = main_chain.fork_at_height(3);
 
-               let mut listener_1 = MockChainListener::new()
+               let listener_1 = MockChainListener::new()
                        .expect_block_disconnected(*fork_chain_1.at_height(4))
                        .expect_block_disconnected(*fork_chain_1.at_height(3))
                        .expect_block_disconnected(*fork_chain_1.at_height(2))
                        .expect_block_connected(*main_chain.at_height(2))
                        .expect_block_connected(*main_chain.at_height(3))
                        .expect_block_connected(*main_chain.at_height(4));
-               let mut listener_2 = MockChainListener::new()
+               let listener_2 = MockChainListener::new()
                        .expect_block_disconnected(*fork_chain_2.at_height(4))
                        .expect_block_disconnected(*fork_chain_2.at_height(3))
                        .expect_block_connected(*main_chain.at_height(3))
                        .expect_block_connected(*main_chain.at_height(4));
-               let mut listener_3 = MockChainListener::new()
+               let listener_3 = MockChainListener::new()
                        .expect_block_disconnected(*fork_chain_3.at_height(4))
                        .expect_block_connected(*main_chain.at_height(4));
 
                let listeners = vec![
-                       (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
-                       (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
-                       (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
+                       (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
+                       (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
+                       (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
                ];
                let mut cache = fork_chain_1.header_cache(2..=4);
                cache.extend(fork_chain_2.header_cache(3..=4));
@@ -304,21 +304,21 @@ mod tests {
                let fork_chain_2 = fork_chain_1.fork_at_height(2);
                let fork_chain_3 = fork_chain_2.fork_at_height(3);
 
-               let mut listener_1 = MockChainListener::new()
+               let listener_1 = MockChainListener::new()
                        .expect_block_disconnected(*fork_chain_1.at_height(4))
                        .expect_block_disconnected(*fork_chain_1.at_height(3))
                        .expect_block_disconnected(*fork_chain_1.at_height(2))
                        .expect_block_connected(*main_chain.at_height(2))
                        .expect_block_connected(*main_chain.at_height(3))
                        .expect_block_connected(*main_chain.at_height(4));
-               let mut listener_2 = MockChainListener::new()
+               let listener_2 = MockChainListener::new()
                        .expect_block_disconnected(*fork_chain_2.at_height(4))
                        .expect_block_disconnected(*fork_chain_2.at_height(3))
                        .expect_block_disconnected(*fork_chain_2.at_height(2))
                        .expect_block_connected(*main_chain.at_height(2))
                        .expect_block_connected(*main_chain.at_height(3))
                        .expect_block_connected(*main_chain.at_height(4));
-               let mut listener_3 = MockChainListener::new()
+               let listener_3 = MockChainListener::new()
                        .expect_block_disconnected(*fork_chain_3.at_height(4))
                        .expect_block_disconnected(*fork_chain_3.at_height(3))
                        .expect_block_disconnected(*fork_chain_3.at_height(2))
@@ -327,9 +327,9 @@ mod tests {
                        .expect_block_connected(*main_chain.at_height(4));
 
                let listeners = vec![
-                       (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
-                       (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
-                       (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
+                       (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
+                       (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
+                       (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
                ];
                let mut cache = fork_chain_1.header_cache(2..=4);
                cache.extend(fork_chain_2.header_cache(3..=4));
@@ -347,11 +347,11 @@ mod tests {
                let new_tip = main_chain.tip();
                let old_tip = fork_chain.tip();
 
-               let mut listener = MockChainListener::new()
+               let listener = MockChainListener::new()
                        .expect_block_disconnected(*old_tip)
                        .expect_block_connected(*new_tip);
 
-               let listeners = vec![(old_tip.block_hash, &mut listener as &mut dyn chain::Listen)];
+               let listeners = vec![(old_tip.block_hash, &listener as &dyn chain::Listen)];
                let mut cache = fork_chain.header_cache(2..=2);
                match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
                        Ok(_) => {