Fix clippy and enable clippy on CI

src/geometry/broad_phase_multi_sap/broad_phase.rs

@@ -445,9 +445,8 @@ impl BroadPhase {
             );
         }
 
-        let need_region_propagation = !layer.created_regions.is_empty();
-
-        need_region_propagation
+        // Returns true if propagation is needed.
+        !layer.created_regions.is_empty()
     }
 
     /// Updates the broad-phase, taking into account the new collider positions.

src/geometry/broad_phase_multi_sap/mod.rs

@@ -2,12 +2,12 @@ pub use self::broad_phase::BroadPhase;
 pub use self::broad_phase_pair_event::{BroadPhasePairEvent, ColliderPair};
 pub use self::sap_proxy::SAPProxyIndex;
 
-pub(self) use self::sap_axis::*;
-pub(self) use self::sap_endpoint::*;
-pub(self) use self::sap_layer::*;
-pub(self) use self::sap_proxy::*;
-pub(self) use self::sap_region::*;
-pub(self) use self::sap_utils::*;
+use self::sap_axis::*;
+use self::sap_endpoint::*;
+use self::sap_layer::*;
+use self::sap_proxy::*;
+use self::sap_region::*;
+use self::sap_utils::*;
 
 mod broad_phase;
 mod broad_phase_pair_event;

src/geometry/broad_phase_multi_sap/sap_axis.rs

@@ -65,9 +65,8 @@ impl SAPAxis {
                 proxy.aabb,
                 self.min_bound
             );
-            let start_endpoint =
-                SAPEndpoint::start_endpoint(proxy.aabb.mins[dim], *proxy_id as u32);
-            let end_endpoint = SAPEndpoint::end_endpoint(proxy.aabb.maxs[dim], *proxy_id as u32);
+            let start_endpoint = SAPEndpoint::start_endpoint(proxy.aabb.mins[dim], *proxy_id);
+            let end_endpoint = SAPEndpoint::end_endpoint(proxy.aabb.maxs[dim], *proxy_id);
 
             self.new_endpoints.push((start_endpoint, 0));
             self.new_endpoints.push((end_endpoint, 0));

src/geometry/broad_phase_multi_sap/sap_proxy.rs

@@ -15,10 +15,7 @@ pub enum SAPProxyData {
 
 impl SAPProxyData {
     pub fn is_region(&self) -> bool {
-        match self {
-            SAPProxyData::Region(_) => true,
-            _ => false,
-        }
+        matches!(self, SAPProxyData::Region(_))
     }
 
     pub fn as_region(&self) -> &SAPRegion {
@@ -102,7 +99,7 @@ impl SAPProxies {
     }
 
     pub fn insert(&mut self, proxy: SAPProxy) -> SAPProxyIndex {
-        let result = if self.first_free != NEXT_FREE_SENTINEL {
+        if self.first_free != NEXT_FREE_SENTINEL {
             let proxy_id = self.first_free;
             self.first_free = self.elements[proxy_id as usize].next_free;
             self.elements[proxy_id as usize] = proxy;
@@ -110,15 +107,13 @@ impl SAPProxies {
         } else {
             self.elements.push(proxy);
             self.elements.len() as u32 - 1
-        };
-
-        result
+        }
     }
 
     pub fn remove(&mut self, proxy_id: SAPProxyIndex) {
         let proxy = &mut self.elements[proxy_id as usize];
         proxy.next_free = self.first_free;
-        self.first_free = proxy_id as u32;
+        self.first_free = proxy_id;
     }
 
     // NOTE: this must not take holes into account.

src/geometry/broad_phase_multi_sap/sap_region.rs

@@ -73,6 +73,7 @@ impl SAPRegion {
         old
     }
 
+    #[allow(clippy::vec_box)] // PERF: see if Box actually makes it faster (due to less copying).
     pub fn recycle_or_new(bounds: Aabb, pool: &mut Vec<Box<Self>>) -> Box<Self> {
         if let Some(old) = pool.pop() {
             Self::recycle(bounds, old)