feat: add missing Default implementations (#509)

Thanks, clippy!

Author: hawkw

alloc/src/bump.rs

@@ -51,6 +51,12 @@ impl<const SIZE: usize> Alloc<SIZE> {
     }
 }
 
+impl<const SIZE: usize> Default for Alloc<SIZE> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 unsafe impl<const SIZE: usize> GlobalAlloc for Alloc<SIZE> {
     /// # Safety
     ///

bitfield/src/bitfield.rs

@@ -419,6 +419,10 @@ macro_rules! bitfield {
             /// Constructs a new instance of `Self` with all bits set to 0.
             #[inline]
             #[must_use]
+            // Allow "new without default", as the user may wish to derive
+            // default or provide their own implementation with different values
+            // from `new`.
+            #[allow(clippy::new_without_default)]
             $vis const fn new() -> Self {
                 Self(0)
             }

hal-x86_64/src/cpu/entropy.rs

@@ -69,7 +69,7 @@ pub fn seed_rng<R: SeedableRng>() -> R {
 #[derive(Debug, Copy, Clone)]
 pub struct Rdrand(());
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, Default)]
 pub struct PitEntropy(());
 
 // === impl Rdrand ===

hal-x86_64/src/interrupt/idt.rs

@@ -237,6 +237,12 @@ impl Idt {
     }
 }
 
+impl Default for Idt {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl fmt::Debug for Idt {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         let Self { descriptors } = self;

hal-x86_64/src/segment.rs

@@ -396,6 +396,12 @@ impl<const SIZE: usize> Gdt<SIZE> {
     }
 }
 
+impl<const SIZE: usize> Default for Gdt<SIZE> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl<const SIZE: usize> fmt::Debug for Gdt<SIZE> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         struct GdtEntries<'a, const SIZE: usize>(&'a Gdt<SIZE>);

maitake-sync/src/wait_cell.rs

@@ -103,6 +103,12 @@ impl WaitCell {
     }
 }
 
+impl Default for WaitCell {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl WaitCell {
     /// Poll to wait on this `WaitCell`, consuming a stored wakeup or
     /// registering the [`Waker`] from the provided [`Context`] to be woken by

maitake-sync/src/wait_map.rs

@@ -465,6 +465,16 @@ impl<K: PartialEq, V> WaitMap<K, V> {
     }
 }
 
+impl<K, V, Lock> Default for WaitMap<K, V, Lock>
+where
+    K: PartialEq,
+    Lock: ScopedRawMutex + Default,
+{
+    fn default() -> Self {
+        Self::new_with_raw_mutex(Lock::default())
+    }
+}
+
 impl<K, V, Lock> WaitMap<K, V, Lock>
 where
     K: PartialEq,

maitake-sync/src/wait_queue.rs

@@ -379,6 +379,15 @@ impl WaitQueue {
     }
 }
 
+impl<Lock> Default for WaitQueue<Lock>
+where
+    Lock: ScopedRawMutex + Default,
+{
+    fn default() -> Self {
+        Self::new_with_raw_mutex(Lock::default())
+    }
+}
+
 impl<Lock> WaitQueue<Lock>
 where
     Lock: ScopedRawMutex,

maitake/src/scheduler.rs

@@ -528,6 +528,9 @@ struct Core {
 impl TaskStub {
     loom_const_fn! {
         /// Create a new unique stub [`Task`].
+        // Thee whole point of this thing is to be const-initialized, so a
+        // non-const-fn `Default` impl is basically useless.
+        #[allow(clippy::new_without_default)]
         pub fn new() -> Self {
             Self {
                 hdr: Header::new_static_stub(),

pci/src/addr.rs

@@ -109,6 +109,12 @@ impl Address {
     }
 }
 
+impl Default for Address {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 impl fmt::Display for Address {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::LowerHex::fmt(self, f)

src/allocator.rs

@@ -84,6 +84,12 @@ impl Allocator {
     }
 }
 
+impl Default for Allocator {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 unsafe impl GlobalAlloc for Allocator {
     #[inline]
     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {