diff --git a/library/alloc/src/slice.rs b/library/alloc/src/slice.rs index e3c7835f1d10b..edc8d99f2f990 100644 --- a/library/alloc/src/slice.rs +++ b/library/alloc/src/slice.rs @@ -27,6 +27,8 @@ pub use core::slice::ArrayChunksMut; pub use core::slice::ArrayWindows; #[stable(feature = "inherent_ascii_escape", since = "1.60.0")] pub use core::slice::EscapeAscii; +#[unstable(feature = "get_many_mut", issue = "104642")] +pub use core::slice::GetManyMutError; #[stable(feature = "slice_get_slice", since = "1.28.0")] pub use core::slice::SliceIndex; #[cfg(not(no_global_oom_handling))] diff --git a/library/core/src/error.rs b/library/core/src/error.rs index 95a39cc3aed38..91549f49f9f9d 100644 --- a/library/core/src/error.rs +++ b/library/core/src/error.rs @@ -1076,4 +1076,4 @@ impl Error for crate::time::TryFromFloatSecsError {} impl Error for crate::ffi::FromBytesUntilNulError {} #[unstable(feature = "get_many_mut", issue = "104642")] -impl Error for crate::slice::GetManyMutError {} +impl Error for crate::slice::GetManyMutError {} diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs index ee91479bb1a9d..40b197f8f18a7 100644 --- a/library/core/src/slice/mod.rs +++ b/library/core/src/slice/mod.rs @@ -4627,13 +4627,11 @@ impl [T] { pub fn get_many_mut( &mut self, indices: [I; N], - ) -> Result<[&mut I::Output; N], GetManyMutError> + ) -> Result<[&mut I::Output; N], GetManyMutError> where I: GetManyMutIndex + SliceIndex, { - if !get_many_check_valid(&indices, self.len()) { - return Err(GetManyMutError { _private: () }); - } + get_many_check_valid(&indices, self.len())?; // SAFETY: The `get_many_check_valid()` call checked that all indices // are disjunct and in bounds. unsafe { Ok(self.get_many_unchecked_mut(indices)) } @@ -4976,53 +4974,59 @@ impl SlicePattern for [T; N] { /// This will do `binomial(N + 1, 2) = N * (N + 1) / 2 = 0, 1, 3, 6, 10, ..` /// comparison operations. #[inline] -fn get_many_check_valid(indices: &[I; N], len: usize) -> bool { +fn get_many_check_valid( + indices: &[I; N], + len: usize, +) -> Result<(), GetManyMutError> { // NB: The optimizer should inline the loops into a sequence // of instructions without additional branching. - let mut valid = true; for (i, idx) in indices.iter().enumerate() { - valid &= idx.is_in_bounds(len); + if !idx.is_in_bounds(len) { + return Err(GetManyMutError::IndexOutOfBounds); + } for idx2 in &indices[..i] { - valid &= !idx.is_overlapping(idx2); + if idx.is_overlapping(idx2) { + return Err(GetManyMutError::OverlappingIndices); + } } } - valid + Ok(()) } -/// The error type returned by [`get_many_mut`][`slice::get_many_mut`]. +/// The error type returned by [`get_many_mut`][`slice::get_many_mut`]. /// /// It indicates one of two possible errors: /// - An index is out-of-bounds. -/// - The same index appeared multiple times in the array. +/// - The same index appeared multiple times in the array +/// (or different but overlapping indices when ranges are provided). /// /// # Examples /// /// ``` /// #![feature(get_many_mut)] +/// use std::slice::GetManyMutError; /// /// let v = &mut [1, 2, 3]; -/// assert!(v.get_many_mut([0, 999]).is_err()); -/// assert!(v.get_many_mut([1, 1]).is_err()); +/// assert_eq!(v.get_many_mut([0, 999]), Err(GetManyMutError::IndexOutOfBounds)); +/// assert_eq!(v.get_many_mut([1, 1]), Err(GetManyMutError::OverlappingIndices)); /// ``` #[unstable(feature = "get_many_mut", issue = "104642")] -// NB: The N here is there to be forward-compatible with adding more details -// to the error type at a later point -#[derive(Clone, PartialEq, Eq)] -pub struct GetManyMutError { - _private: (), +#[derive(Debug, Clone, PartialEq, Eq)] +pub enum GetManyMutError { + /// An index provided was out-of-bounds for the slice. + IndexOutOfBounds, + /// Two indices provided were overlapping. + OverlappingIndices, } #[unstable(feature = "get_many_mut", issue = "104642")] -impl fmt::Debug for GetManyMutError { +impl fmt::Display for GetManyMutError { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_struct("GetManyMutError").finish_non_exhaustive() - } -} - -#[unstable(feature = "get_many_mut", issue = "104642")] -impl fmt::Display for GetManyMutError { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - fmt::Display::fmt("an index is out of bounds or appeared multiple times in the array", f) + let msg = match self { + GetManyMutError::IndexOutOfBounds => "an index is out of bounds", + GetManyMutError::OverlappingIndices => "there were overlapping indices", + }; + fmt::Display::fmt(msg, f) } }