add safety comments and simplify some code

azalea-core/src/bitset.rs

@@ -143,10 +143,12 @@ where
         }
     }
 
+    #[inline]
     pub fn index(&self, index: usize) -> bool {
         (self.data[index / 8] & (1u8 << (index % 8))) != 0
     }
 
+    #[inline]
     pub fn set(&mut self, bit_index: usize) {
         self.data[bit_index / 8] |= 1u8 << (bit_index % 8);
     }

azalea-core/src/position.rs

@@ -261,7 +261,6 @@ impl ChunkSectionPos {
 }
 /// The coordinates of a block inside a chunk.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
-#[repr(align(8))]
 pub struct ChunkBlockPos {
     pub x: u8,
     pub y: i32,
@@ -300,7 +299,6 @@ impl nohash_hasher::IsEnabled for ChunkBlockPos {}
 /// The coordinates of a block inside a chunk section. Each coordinate must be
 /// in the range [0, 15].
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
-#[repr(align(4))]
 pub struct ChunkSectionBlockPos {
     pub x: u8,
     pub y: u8,
@@ -330,14 +328,7 @@ impl Hash for ChunkSectionBlockPos {
 impl From<ChunkSectionBlockPos> for u16 {
     #[inline]
     fn from(pos: ChunkSectionBlockPos) -> Self {
-        let mut val: u16 = 0;
-        // first 4 bits are z
-        val |= pos.z as u16;
-        // next 4 bits are y
-        val |= (pos.y as u16) << 4;
-        // last 4 bits are x
-        val |= (pos.x as u16) << 8;
-        val
+        (pos.z as u16) | ((pos.y as u16) << 4) | ((pos.x as u16) << 8)
     }
 }
 impl nohash_hasher::IsEnabled for ChunkSectionBlockPos {}

azalea/src/pathfinder/moves/mod.rs

@@ -131,6 +131,7 @@ impl PathfinderCtx {
         let (section_pos, section_block_pos) =
             (ChunkSectionPos::from(pos), ChunkSectionBlockPos::from(pos));
         let index = u16::from(section_block_pos) as usize;
+        // SAFETY: we're only accessing this from one thread
         let cached_block_passable = unsafe { &mut *self.cached_block_passable.get() };
         if let Some(cached) = cached_block_passable.iter_mut().find_map(|cached| {
             if cached.pos == section_pos {
@@ -183,6 +184,7 @@ impl PathfinderCtx {
         let (section_pos, section_block_pos) =
             (ChunkSectionPos::from(pos), ChunkSectionBlockPos::from(pos));
         let index = u16::from(section_block_pos) as usize;
+        // SAFETY: we're only accessing this from one thread
         let cached_block_solid = unsafe { &mut *self.cached_block_solid.get() };
         if let Some(cached) = cached_block_solid.iter_mut().find_map(|cached| {
             if cached.pos == section_pos {