chore(consensus): add lints to consensus (#1851)

Lior banned `as` repo-wide, unless absolutely necessary.

Nearly all as uses can be replaced with [Try]From which doesn't have
implicit coercions like as (we encountered several bugs due to these coercions).

Motivation: we are standardizing lints across the repo and CI, instead
of each crate having separate sets of lints.

Co-Authored-By: Gilad Chase <[email protected]>

crates/sequencing/papyrus_consensus/Cargo.toml

@@ -35,3 +35,6 @@ papyrus_network_types = { workspace = true, features = ["testing"] }
 papyrus_storage = { workspace = true, features = ["testing"] }
 papyrus_test_utils.workspace = true
 test-case.workspace = true
+
+[lints]
+workspace = true

crates/sequencing/papyrus_consensus/src/bin/run_simulation.rs

@@ -62,9 +62,10 @@ impl Node {
 
     async fn stop(&mut self) {
         let process = self.process.as_mut().expect("Process not found");
-        let pid = process.id().unwrap();
+        let pid = i32::try_from(process.id().unwrap())
+            .expect("Max PIDs on unix are way smaller than i32::MAX");
         // Send SIGINT to the entire process group to terminate the process and its subprocesses
-        nix::sys::signal::killpg(Pid::from_raw(pid as i32), nix::sys::signal::Signal::SIGINT)
+        nix::sys::signal::killpg(Pid::from_raw(pid), nix::sys::signal::Signal::SIGINT)
             .expect("Failed to kill process group");
     }
 
@@ -296,7 +297,9 @@ async fn build_node(data_dir: &str, logs_dir: &str, i: usize, papyrus_args: &Pap
         ("invalid_probability", papyrus_args.invalid_probability),
         // Convert optional parameters to f64 for consistency in the vector,
         // types were validated during parsing.
+        #[allow(clippy::as_conversions)] // Note: no precision loss if cache size is < ~8PetaBytes.
         ("cache_size", papyrus_args.cache_size.map(|v| v as f64)),
+        #[allow(clippy::as_conversions)] // Note: precision loss for random doesn't matter.
         ("random_seed", papyrus_args.random_seed.map(|v| v as f64)),
     ];
     for (key, value) in conditional_test_params {

crates/sequencing/papyrus_consensus/src/manager.rs

@@ -61,6 +61,7 @@ where
     tokio::time::sleep(consensus_delay).await;
     let mut current_height = start_height;
     let mut manager = MultiHeightManager::new(validator_id, timeouts);
+    #[allow(clippy::as_conversions)] // FIXME: use int metrics so `as f64` may be removed.
     loop {
         metrics::gauge!(PAPYRUS_CONSENSUS_HEIGHT, current_height.0 as f64);
 

crates/sequencing/papyrus_consensus/src/simulation_network_receiver.rs

@@ -95,6 +95,7 @@ impl NetworkReceiver {
     }
 
     fn should_drop_msg(&self, msg_hash: u64) -> bool {
+        #[allow(clippy::as_conversions)]
         let prob = (msg_hash as f64) / (u64::MAX as f64);
         prob <= self.drop_probability
     }
@@ -104,6 +105,7 @@ impl NetworkReceiver {
         mut msg: ConsensusMessage,
         msg_hash: u64,
     ) -> ConsensusMessage {
+        #[allow(clippy::as_conversions)]
         if (msg_hash as f64) / (u64::MAX as f64) > self.invalid_probability {
             return msg;
         }

crates/sequencing/papyrus_consensus/src/single_height_consensus.rs

@@ -168,7 +168,9 @@ impl SingleHeightConsensus {
         timeouts: TimeoutsConfig,
     ) -> Self {
         // TODO(matan): Use actual weights, not just `len`.
-        let state_machine = StateMachine::new(id, validators.len() as u32);
+        let n_validators =
+            u32::try_from(validators.len()).expect("Should have way less than u32::MAX validators");
+        let state_machine = StateMachine::new(id, n_validators);
         Self {
             height,
             validators,
@@ -566,7 +568,11 @@ impl SingleHeightConsensus {
             })
             .collect();
         // TODO(matan): Check actual weights.
-        assert!(supporting_precommits.len() >= self.state_machine.quorum_size() as usize);
+        assert!(
+            supporting_precommits.len()
+                >= usize::try_from(self.state_machine.quorum_size())
+                    .expect("u32 should fit in usize")
+        );
         Ok(ShcReturn::Decision(Decision { precommits: supporting_precommits, block }))
     }
 }