Add support for defmt

Author: darkwater

Cargo.toml

@@ -32,6 +32,7 @@ malloc_size_of = { version = "0.1", optional = true, default-features = false }
 arbitrary = { version = "1", optional = true }
 bincode = { version = "2", optional = true, default-features = false }
 unty = { version = "0.0.4", optional = true, default-features = false }
+defmt = { version = "1", optional = true }
 
 [dev-dependencies]
 bincode1 = { package = "bincode", version = "1.0.1" }

src/lib.rs

@@ -56,6 +56,10 @@
 //! For details, see the
 //! [Rust Reference](https://doc.rust-lang.org/reference/const_eval.html#const-functions).
 //!
+//! ### `defmt`
+//!
+//! When this feature is enabled, `SmallVec` implements the `defmt::Format` trait.
+//!
 //! ### `drain_filter`
 //!
 //! **This feature is unstable.** It may change to match the unstable `drain_filter` method in libstd.
@@ -295,6 +299,7 @@ impl<T: Clone> ExtendFromSlice<T> for Vec<T> {
 }
 
 /// Error type for APIs with fallible heap allocation
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[derive(Debug)]
 pub enum CollectionAllocErr {
     /// Overflow `usize::MAX` or other error during size computation
@@ -364,6 +369,16 @@ where
     }
 }
 
+#[cfg(feature = "defmt")]
+impl<'a, T: 'a + Array> defmt::Format for Drain<'a, T>
+where
+    T::Item: defmt::Format,
+{
+    fn format(&self, fmt: defmt::Formatter) {
+        defmt::write!(fmt, "Drain({=[?]})", self.iter.as_slice());
+    }
+}
+
 unsafe impl<'a, T: Sync + Array> Sync for Drain<'a, T> {}
 unsafe impl<'a, T: Send + Array> Send for Drain<'a, T> {}
 
@@ -2122,6 +2137,16 @@ where
     }
 }
 
+#[cfg(feature = "defmt")]
+impl<A: Array> defmt::Format for SmallVec<A>
+where
+    A::Item: defmt::Format,
+{
+    fn format(&self, fmt: defmt::Formatter) {
+        defmt::write!(fmt, "[{=[?]}]", self.as_slice());
+    }
+}
+
 impl<A: Array> Default for SmallVec<A> {
     #[inline]
     fn default() -> SmallVec<A> {
@@ -2245,6 +2270,16 @@ where
     }
 }
 
+#[cfg(feature = "defmt")]
+impl<A: Array> defmt::Format for IntoIter<A>
+where
+    A::Item: defmt::Format,
+{
+    fn format(&self, fmt: defmt::Formatter) {
+        defmt::write!(fmt, "IntoIter({=[?]})", self.as_slice());
+    }
+}
+
 impl<A: Array + Clone> Clone for IntoIter<A>
 where
     A::Item: Clone,