refactor: new error system

src/errors.rs

@@ -1,20 +1,38 @@
-use core::alloc::Layout;
+use {
+    alloc::alloc::handle_alloc_error,
+    core::{
+        alloc::Layout,
+        error::Error,
+        fmt::{
+            Debug,
+            Display,
+            Formatter,
+            Result as Format
+        }
+    }
+};
 
-/// Error type for APIs with fallible heap allocation
 #[derive(Debug)]
-pub enum CollectionAllocErr {
-    /// Overflow `usize::MAX` or other error during size computation
+pub enum SmallVecError {
     CapacityOverflow,
-    /// The allocator return an error
-    AllocErr {
-        /// The layout that was passed to the allocator
-        layout: Layout
-    }
+    AllocationError(Layout)
 }
-impl core::fmt::Display for CollectionAllocErr {
-    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-        write!(f, "Allocation error: {:?}", self)
+
+impl Display for SmallVecError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Format {
+        write!(f, "Allocation error: {self:?}")
     }
 }
 
-impl core::error::Error for CollectionAllocErr {}
+impl Error for SmallVecError {}
+
+impl SmallVecError {
+    #[cold]
+    #[inline(never)]
+    pub fn handle<Type>(self) -> Type {
+        match self {
+            SmallVecError::CapacityOverflow => panic!("capacity overflow"),
+            SmallVecError::AllocationError(layout) => handle_alloc_error(layout)
+        }
+    }
+}

src/iterators/drain.rs

@@ -1,7 +1,7 @@
 use crate::{
     Allocator,
     SmallVec,
-    infallible
+    SmallVecError
 };
 
 /// An iterator that removes the items from a `SmallVec` and yields them by
@@ -180,7 +180,7 @@ impl<T, const N: usize, A: Allocator> Drain<'_, T, N, A> {
         let result = vec.try_reserve(additional);
         // Restore the prefix length before a reservation error can panic.
         unsafe { vec.set_len(old_len) };
-        infallible(result);
+        result.unwrap_or_else(SmallVecError::handle);
 
         let new_tail_start = self.tail_start + additional;
         unsafe {

src/lib.rs

@@ -53,7 +53,7 @@ use defmt::{
     Formatter as DeFormatter,
     write as dewrite
 };
-pub use errors::CollectionAllocErr;
+pub use errors::SmallVecError;
 #[cfg(feature = "std")]
 use std::io;
 use {
@@ -93,17 +93,6 @@ use {
     taggedlen::TaggedLen
 };
 
-#[inline]
-fn infallible<T>(result: Result<T, CollectionAllocErr>) -> T {
-    match result {
-        Ok(x) => x,
-        Err(CollectionAllocErr::CapacityOverflow) => panic!("capacity overflow"),
-        Err(CollectionAllocErr::AllocErr {
-            layout
-        }) => alloc::alloc::handle_alloc_error(layout)
-    }
-}
-
 #[inline]
 /// A local copy of [`core::slice::range`]. The latter function is unstable
 /// and thus cannot be used yet.
@@ -440,7 +429,7 @@ impl<T, const N: usize> SmallVec<T, N> {
         Self::new_in(Global)
     }
 
-    pub fn try_with_capacity(capacity: usize) -> Result<Self, CollectionAllocErr> {
+    pub fn try_with_capacity(capacity: usize) -> Result<Self, SmallVecError> {
         Self::try_with_capacity_in(capacity, Global)
     }
 
@@ -972,11 +961,12 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
 
     #[inline]
     pub fn grow(&mut self, new_capacity: usize) {
-        infallible(self.try_grow(new_capacity));
+        self.try_grow(new_capacity)
+            .unwrap_or_else(SmallVecError::handle);
     }
 
     #[cold]
-    pub fn try_grow(&mut self, new_capacity: usize) -> Result<(), CollectionAllocErr> {
+    pub fn try_grow(&mut self, new_capacity: usize) -> Result<(), SmallVecError> {
         if Self::IS_ZST {
             return Ok(());
         }
@@ -1022,24 +1012,24 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
     pub fn reserve(&mut self, additional: usize) {
         // can't overflow since len <= capacity
         if additional > self.capacity() - self.len() {
-            let new_capacity = infallible(
-                self.len()
-                    .checked_add(additional)
-                    .and_then(usize::checked_next_power_of_two)
-                    .ok_or(CollectionAllocErr::CapacityOverflow)
-            );
+            let new_capacity = self
+                .len()
+                .checked_add(additional)
+                .and_then(usize::checked_next_power_of_two)
+                .ok_or(SmallVecError::CapacityOverflow)
+                .unwrap_or_else(SmallVecError::handle);
             self.grow(new_capacity);
         }
     }
 
     #[inline]
-    pub fn try_reserve(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
+    pub fn try_reserve(&mut self, additional: usize) -> Result<(), SmallVecError> {
         if additional > self.capacity() - self.len() {
             let new_capacity = self
                 .len()
                 .checked_add(additional)
                 .and_then(usize::checked_next_power_of_two)
-                .ok_or(CollectionAllocErr::CapacityOverflow)?;
+                .ok_or(SmallVecError::CapacityOverflow)?;
             self.try_grow(new_capacity)
         } else {
             Ok(())
@@ -1050,22 +1040,22 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
     pub fn reserve_exact(&mut self, additional: usize) {
         // can't overflow since len <= capacity
         if additional > self.capacity() - self.len() {
-            let new_capacity = infallible(
-                self.len()
-                    .checked_add(additional)
-                    .ok_or(CollectionAllocErr::CapacityOverflow)
-            );
+            let new_capacity = self
+                .len()
+                .checked_add(additional)
+                .ok_or(SmallVecError::CapacityOverflow)
+                .unwrap_or_else(SmallVecError::handle);
             self.grow(new_capacity);
         }
     }
 
     #[inline]
-    pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
+    pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), SmallVecError> {
         if additional > self.capacity() - self.len() {
             let new_capacity = self
                 .len()
                 .checked_add(additional)
-                .ok_or(CollectionAllocErr::CapacityOverflow)?;
+                .ok_or(SmallVecError::CapacityOverflow)?;
             self.try_grow(new_capacity)
         } else {
             Ok(())
@@ -1093,7 +1083,11 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
             // SAFETY: len > Self::inline_size() >= 0
             // so new capacity is non zero, it is equal to the length
             // T can't be a ZST because SmallVec<ZST, N> is never spilled.
-            unsafe { infallible(self.raw.try_grow_raw(self.len, len)) };
+            unsafe {
+                self.raw
+                    .try_grow_raw(self.len, len)
+                    .unwrap_or_else(SmallVecError::handle)
+            };
         }
     }
 
@@ -1125,7 +1119,11 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
                 // SAFETY: len > Self::inline_size() >= 0
                 // so new capacity is non zero, it is equal to the length
                 // T can't be a ZST because SmallVec<ZST, N> is never spilled.
-                unsafe { infallible(self.raw.try_grow_raw(self.len, target)) };
+                unsafe {
+                    self.raw
+                        .try_grow_raw(self.len, target)
+                        .unwrap_or_else(SmallVecError::handle)
+                };
             }
         }
     }
@@ -1674,7 +1672,7 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
         }
     }
 
-    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, CollectionAllocErr> {
+    pub fn try_with_capacity_in(capacity: usize, alloc: A) -> Result<Self, SmallVecError> {
         let mut this = Self::new_in(alloc);
         if capacity > Self::inline_size() && !Self::IS_ZST {
             // SAFETY: we checked all the preconditions
@@ -1687,7 +1685,7 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
     }
 
     pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
-        infallible(Self::try_with_capacity_in(capacity, alloc))
+        Self::try_with_capacity_in(capacity, alloc).unwrap_or_else(SmallVecError::handle)
     }
 }
 

src/rawsmallvec.rs

@@ -1,7 +1,7 @@
 use {
     super::{
         Allocator,
-        CollectionAllocErr,
+        SmallVecError,
         taggedlen::TaggedLen
     },
     core::{
@@ -122,7 +122,7 @@ impl<T, const N: usize, A: Allocator> RawSmallVec<T, N, A> {
         &mut self,
         len: TaggedLen<T>,
         new_capacity: usize
-    ) -> Result<(), CollectionAllocErr> {
+    ) -> Result<(), SmallVecError> {
         let (len, was_on_heap) = len.parts();
         debug_assert!(!Self::IS_ZST);
         debug_assert!(new_capacity > 0 && new_capacity >= len);
@@ -131,9 +131,9 @@ impl<T, const N: usize, A: Allocator> RawSmallVec<T, N, A> {
         let ptr = unsafe { self.as_mut_ptr(was_on_heap) };
 
         let new_layout =
-            Layout::array::<T>(new_capacity).map_err(|_| CollectionAllocErr::CapacityOverflow)?;
+            Layout::array::<T>(new_capacity).map_err(|_| SmallVecError::CapacityOverflow)?;
         if new_layout.size() > isize::MAX as usize {
-            return Err(CollectionAllocErr::CapacityOverflow);
+            return Err(SmallVecError::CapacityOverflow);
         }
 
         let new_ptr = if !was_on_heap {
@@ -142,9 +142,7 @@ impl<T, const N: usize, A: Allocator> RawSmallVec<T, N, A> {
             let new_ptr = self
                 .alloc
                 .allocate(new_layout)
-                .map_err(|_| CollectionAllocErr::AllocErr {
-                    layout: new_layout
-                })?
+                .map_err(|_| SmallVecError::AllocationError(new_layout))?
                 .cast();
             unsafe { copy_nonoverlapping(ptr, new_ptr.as_ptr(), len) };
             new_ptr
@@ -178,9 +176,7 @@ impl<T, const N: usize, A: Allocator> RawSmallVec<T, N, A> {
                     new_layout
                 )
             }
-            .map_err(|_| CollectionAllocErr::AllocErr {
-                layout: new_layout
-            })?
+            .map_err(|_| SmallVecError::AllocationError(new_layout))?
             .cast()
         };
         self.inner.heap = (new_ptr, new_capacity);