Merge pull request #533 from newAM/fix-clippy-result-unit-error

Remove allow(clippy::result_unit_err)

Author: newAM

CHANGELOG.md

@@ -44,6 +44,14 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Changed
 
+- Changed the error type of these methods from `()` to `CapacityError`.
+  - `String::push_str`
+  - `String::push`
+  - `Vec::extend_from_slice`
+  - `Vec::from_slice`
+  - `Vec::resize_default`
+  - `Vec::resize`
+- Renamed `FromUtf16Error::DecodeUtf16Error` to `FromUtf16Error::DecodeUtf16`.
 - Changed `stable_deref_trait` to a platform-dependent dependency.
 - Changed `SortedLinkedList::pop` return type from `Result<T, ()>` to `Option<T>` to match `std::vec::pop`.
 - `Vec::capacity` is no longer a `const` function.

src/lib.rs

@@ -233,3 +233,16 @@ mod ufmt;
 pub mod _export {
     pub use crate::string::format;
 }
+
+/// The error type for fallible [`Vec`] and [`String`] methods.
+#[derive(Debug)]
+#[non_exhaustive]
+pub struct CapacityError;
+
+impl core::fmt::Display for CapacityError {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        f.write_str("insufficient capacity")
+    }
+}
+
+impl core::error::Error for CapacityError {}

src/string/mod.rs

@@ -12,6 +12,7 @@ use core::{
 };
 
 use crate::vec::{OwnedVecStorage, Vec, VecInner, VecStorage, ViewVecStorage};
+use crate::CapacityError;
 
 mod drain;
 pub use drain::Drain;
@@ -24,20 +25,28 @@ pub use drain::Drain;
 #[derive(Debug)]
 pub enum FromUtf16Error {
     /// The capacity of the `String` is too small for the given operation.
-    Capacity,
+    Capacity(CapacityError),
     /// Error decoding UTF-16.
-    DecodeUtf16Error(DecodeUtf16Error),
+    DecodeUtf16(DecodeUtf16Error),
 }
 
 impl fmt::Display for FromUtf16Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Self::Capacity => "insufficient capacity".fmt(f),
-            Self::DecodeUtf16Error(e) => write!(f, "invalid UTF-16: {}", e),
+            Self::Capacity(err) => write!(f, "{err}"),
+            Self::DecodeUtf16(err) => write!(f, "invalid UTF-16: {err}"),
         }
     }
 }
 
+impl core::error::Error for FromUtf16Error {}
+
+impl From<CapacityError> for FromUtf16Error {
+    fn from(e: CapacityError) -> Self {
+        Self::Capacity(e)
+    }
+}
+
 /// Base struct for [`String`] and [`StringView`], generic over the [`VecStorage`].
 ///
 /// In most cases you should use [`String`] or [`StringView`] directly. Only use this
@@ -164,10 +173,10 @@ impl<const N: usize> String<N> {
         for c in char::decode_utf16(v.iter().cloned()) {
             match c {
                 Ok(c) => {
-                    s.push(c).map_err(|_| FromUtf16Error::Capacity)?;
+                    s.push(c).map_err(|_| CapacityError)?;
                 }
                 Err(err) => {
-                    return Err(FromUtf16Error::DecodeUtf16Error(err));
+                    return Err(FromUtf16Error::DecodeUtf16(err));
                 }
             }
         }
@@ -253,7 +262,7 @@ impl<const N: usize> String<N> {
     /// assert!(b.len() == 2);
     ///
     /// assert_eq!(&[b'a', b'b'], &b[..]);
-    /// # Ok::<(), ()>(())
+    /// # Ok::<(), heapless::CapacityError>(())
     /// ```
     #[inline]
     pub fn into_bytes(self) -> Vec<u8, N> {
@@ -360,7 +369,7 @@ impl<S: VecStorage<u8> + ?Sized> StringInner<S> {
     ///
     /// let _s = s.as_str();
     /// // s.push('c'); // <- cannot borrow `s` as mutable because it is also borrowed as immutable
-    /// # Ok::<(), ()>(())
+    /// # Ok::<(), heapless::CapacityError>(())
     /// ```
     #[inline]
     pub fn as_str(&self) -> &str {
@@ -379,7 +388,7 @@ impl<S: VecStorage<u8> + ?Sized> StringInner<S> {
     /// let mut s: String<4> = String::try_from("ab")?;
     /// let s = s.as_mut_str();
     /// s.make_ascii_uppercase();
-    /// # Ok::<(), ()>(())
+    /// # Ok::<(), heapless::CapacityError>(())
     /// ```
     #[inline]
     pub fn as_mut_str(&mut self) -> &mut str {
@@ -411,7 +420,7 @@ impl<S: VecStorage<u8> + ?Sized> StringInner<S> {
     ///     vec.reverse();
     /// }
     /// assert_eq!(s, "olleh");
-    /// # Ok::<(), ()>(())
+    /// # Ok::<(), heapless::CapacityError>(())
     /// ```
     pub unsafe fn as_mut_vec(&mut self) -> &mut VecInner<u8, S> {
         &mut self.vec
@@ -433,11 +442,10 @@ impl<S: VecStorage<u8> + ?Sized> StringInner<S> {
     /// assert_eq!("foobar", s);
     ///
     /// assert!(s.push_str("tender").is_err());
-    /// # Ok::<(), ()>(())
+    /// # Ok::<(), heapless::CapacityError>(())
     /// ```
     #[inline]
-    #[allow(clippy::result_unit_err)]
-    pub fn push_str(&mut self, string: &str) -> Result<(), ()> {
+    pub fn push_str(&mut self, string: &str) -> Result<(), CapacityError> {
         self.vec.extend_from_slice(string.as_bytes())
     }
 
@@ -476,13 +484,12 @@ impl<S: VecStorage<u8> + ?Sized> StringInner<S> {
     /// assert!("abc123" == s.as_str());
     ///
     /// assert_eq!("abc123", s);
-    /// # Ok::<(), ()>(())
+    /// # Ok::<(), heapless::CapacityError>(())
     /// ```
     #[inline]
-    #[allow(clippy::result_unit_err)]
-    pub fn push(&mut self, c: char) -> Result<(), ()> {
+    pub fn push(&mut self, c: char) -> Result<(), CapacityError> {
         match c.len_utf8() {
-            1 => self.vec.push(c as u8).map_err(|_| {}),
+            1 => self.vec.push(c as u8).map_err(|_| CapacityError),
             _ => self
                 .vec
                 .extend_from_slice(c.encode_utf8(&mut [0; 4]).as_bytes()),
@@ -513,7 +520,7 @@ impl<S: VecStorage<u8> + ?Sized> StringInner<S> {
     /// s.truncate(2);
     ///
     /// assert_eq!("he", s);
-    /// # Ok::<(), ()>(())
+    /// # Ok::<(), heapless::CapacityError>(())
     /// ```
     #[inline]
     pub fn truncate(&mut self, new_len: usize) {
@@ -541,7 +548,7 @@ impl<S: VecStorage<u8> + ?Sized> StringInner<S> {
     /// assert_eq!(s.pop(), Some('f'));
     ///
     /// assert_eq!(s.pop(), None);
-    /// Ok::<(), ()>(())
+    /// Ok::<(), heapless::CapacityError>(())
     /// ```
     pub fn pop(&mut self) -> Option<char> {
         let ch = self.chars().next_back()?;
@@ -615,7 +622,7 @@ impl<S: VecStorage<u8> + ?Sized> StringInner<S> {
     /// assert!(s.is_empty());
     /// assert_eq!(0, s.len());
     /// assert_eq!(8, s.capacity());
-    /// Ok::<(), ()>(())
+    /// Ok::<(), heapless::CapacityError>(())
     /// ```
     #[inline]
     pub fn clear(&mut self) {
@@ -630,7 +637,8 @@ impl<const N: usize> Default for String<N> {
 }
 
 impl<'a, const N: usize> TryFrom<&'a str> for String<N> {
-    type Error = ();
+    type Error = CapacityError;
+
     fn try_from(s: &'a str) -> Result<Self, Self::Error> {
         let mut new = Self::new();
         new.push_str(s)?;
@@ -639,7 +647,7 @@ impl<'a, const N: usize> TryFrom<&'a str> for String<N> {
 }
 
 impl<const N: usize> str::FromStr for String<N> {
-    type Err = ();
+    type Err = CapacityError;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let mut new = Self::new();
@@ -912,7 +920,7 @@ impl_try_from_num!(u64, 20);
 
 #[cfg(test)]
 mod tests {
-    use crate::{String, Vec};
+    use crate::{CapacityError, String, Vec};
 
     #[test]
     fn static_new() {
@@ -980,7 +988,7 @@ mod tests {
         assert!(s.len() == 3);
         assert_eq!(s, "123");
 
-        let _: () = String::<2>::try_from("123").unwrap_err();
+        let _: CapacityError = String::<2>::try_from("123").unwrap_err();
     }
 
     #[test]
@@ -991,7 +999,7 @@ mod tests {
         assert!(s.len() == 3);
         assert_eq!(s, "123");
 
-        let _: () = String::<2>::from_str("123").unwrap_err();
+        let _: CapacityError = String::<2>::from_str("123").unwrap_err();
     }
 
     #[test]

src/ufmt.rs

@@ -1,18 +1,19 @@
 use crate::{
     string::StringInner,
     vec::{VecInner, VecStorage},
+    CapacityError,
 };
 use ufmt_write::uWrite;
 
 impl<S: VecStorage<u8> + ?Sized> uWrite for StringInner<S> {
-    type Error = ();
+    type Error = CapacityError;
     fn write_str(&mut self, s: &str) -> Result<(), Self::Error> {
         self.push_str(s)
     }
 }
 
 impl<S: VecStorage<u8> + ?Sized> uWrite for VecInner<u8, S> {
-    type Error = ();
+    type Error = CapacityError;
     fn write_str(&mut self, s: &str) -> Result<(), Self::Error> {
         self.extend_from_slice(s.as_bytes())
     }

src/vec/mod.rs

@@ -11,6 +11,8 @@ use core::{
     slice,
 };
 
+use crate::CapacityError;
+
 mod drain;
 
 mod storage {
@@ -192,8 +194,7 @@ impl<T, const N: usize> Vec<T, N> {
     /// let mut v: Vec<u8, 16> = Vec::new();
     /// v.extend_from_slice(&[1, 2, 3]).unwrap();
     /// ```
-    #[allow(clippy::result_unit_err)]
-    pub fn from_slice(other: &[T]) -> Result<Self, ()>
+    pub fn from_slice(other: &[T]) -> Result<Self, CapacityError>
     where
         T: Clone,
     {
@@ -516,22 +517,21 @@ impl<T, S: VecStorage<T> + ?Sized> VecInner<T, S> {
     /// vec.extend_from_slice(&[2, 3, 4]).unwrap();
     /// assert_eq!(*vec, [1, 2, 3, 4]);
     /// ```
-    #[allow(clippy::result_unit_err)]
-    pub fn extend_from_slice(&mut self, other: &[T]) -> Result<(), ()>
+    pub fn extend_from_slice(&mut self, other: &[T]) -> Result<(), CapacityError>
     where
         T: Clone,
     {
         pub fn extend_from_slice_inner<T>(
             len: &mut usize,
             buf: &mut [MaybeUninit<T>],
             other: &[T],
-        ) -> Result<(), ()>
+        ) -> Result<(), CapacityError>
         where
             T: Clone,
         {
             if *len + other.len() > buf.len() {
                 // won't fit in the `Vec`; don't modify anything and return an error
-                Err(())
+                Err(CapacityError)
             } else {
                 for elem in other {
                     unsafe { *buf.get_unchecked_mut(*len) = MaybeUninit::new(elem.clone()) }
@@ -626,13 +626,12 @@ impl<T, S: VecStorage<T> + ?Sized> VecInner<T, S> {
     /// `new_len` is less than len, the Vec is simply truncated.
     ///
     /// See also [`resize_default`](Self::resize_default).
-    #[allow(clippy::result_unit_err)]
-    pub fn resize(&mut self, new_len: usize, value: T) -> Result<(), ()>
+    pub fn resize(&mut self, new_len: usize, value: T) -> Result<(), CapacityError>
     where
         T: Clone,
     {
         if new_len > self.capacity() {
-            return Err(());
+            return Err(CapacityError);
         }
 
         if new_len > self.len {
@@ -653,8 +652,7 @@ impl<T, S: VecStorage<T> + ?Sized> VecInner<T, S> {
     /// If `new_len` is less than `len`, the `Vec` is simply truncated.
     ///
     /// See also [`resize`](Self::resize).
-    #[allow(clippy::result_unit_err)]
-    pub fn resize_default(&mut self, new_len: usize) -> Result<(), ()>
+    pub fn resize_default(&mut self, new_len: usize) -> Result<(), CapacityError>
     where
         T: Clone + Default,
     {
@@ -1211,7 +1209,7 @@ impl<T, S: VecStorage<T> + ?Sized> Drop for VecInner<T, S> {
 }
 
 impl<'a, T: Clone, const N: usize> TryFrom<&'a [T]> for Vec<T, N> {
-    type Error = ();
+    type Error = CapacityError;
 
     fn try_from(slice: &'a [T]) -> Result<Self, Self::Error> {
         Self::from_slice(slice)