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Add some conversion trait impls #145504

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20 changes: 20 additions & 0 deletions library/core/src/ascii/ascii_char.rs
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Expand Up @@ -1170,6 +1170,26 @@ macro_rules! into_int_impl {

into_int_impl!(u8 u16 u32 u64 u128 char);

#[unstable(feature = "ascii_char", issue = "110998")]
impl AsRef<str> for AsciiChar {
#[inline(always)]
fn as_ref(&self) -> &str {
self.as_str()
}
}

#[unstable(feature = "ascii_char", issue = "110998")]
impl AsMut<str> for AsciiChar {
#[inline(always)]
fn as_mut(&mut self) -> &mut str {
let ascii_ptr: *mut [Self] = crate::slice::from_mut(self);
let str_ptr = ascii_ptr as *mut str;
// SAFETY: Each ASCII codepoint in UTF-8 is encoded as one single-byte
// code unit having the same value as the ASCII byte.
unsafe { &mut *str_ptr }
}
}
Comment on lines +1182 to +1191
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This could probably be implemented in a new as_mut_str method, similar to as_str

Also, could everything here use #[inline] without the always?


impl [AsciiChar] {
/// Views this slice of ASCII characters as a UTF-8 `str`.
#[unstable(feature = "ascii_char", issue = "110998")]
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24 changes: 24 additions & 0 deletions library/core/src/cell.rs
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Expand Up @@ -671,6 +671,30 @@ impl<T: CoerceUnsized<U>, U> CoerceUnsized<Cell<U>> for Cell<T> {}
#[unstable(feature = "dispatch_from_dyn", issue = "none")]
impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<Cell<U>> for Cell<T> {}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T, const N: usize> AsRef<[Cell<T>; N]> for Cell<[T; N]> {
#[inline(always)]
fn as_ref(&self) -> &[Cell<T>; N] {
self.as_array_of_cells()
}
}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T, const N: usize> AsRef<[Cell<T>]> for Cell<[T; N]> {
#[inline(always)]
fn as_ref(&self) -> &[Cell<T>] {
&*self.as_array_of_cells()
}
}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T> AsRef<[Cell<T>]> for Cell<[T]> {
#[inline(always)]
fn as_ref(&self) -> &[Cell<T>] {
self.as_slice_of_cells()
}
}

impl<T> Cell<[T]> {
/// Returns a `&[Cell<T>]` from a `&Cell<[T]>`
///
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50 changes: 50 additions & 0 deletions library/core/src/mem/maybe_uninit.rs
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Expand Up @@ -1452,6 +1452,56 @@ impl<T, const N: usize> MaybeUninit<[T; N]> {
}
}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T, const N: usize> From<[MaybeUninit<T>; N]> for MaybeUninit<[T; N]> {
#[inline(always)]
fn from(arr: [MaybeUninit<T>; N]) -> Self {
arr.transpose()
}
}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T, const N: usize> AsRef<[MaybeUninit<T>; N]> for MaybeUninit<[T; N]> {
#[inline(always)]
fn as_ref(&self) -> &[MaybeUninit<T>; N] {
// SAFETY: T and MaybeUninit<T> have the same layout
unsafe { &*(self as *const MaybeUninit<[T; N]> as *const [MaybeUninit<T>; N]) }
}
}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T, const N: usize> AsRef<[MaybeUninit<T>]> for MaybeUninit<[T; N]> {
#[inline(always)]
fn as_ref(&self) -> &[MaybeUninit<T>] {
&*AsRef::<[MaybeUninit<T>; N]>::as_ref(self)
}
}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T, const N: usize> AsMut<[MaybeUninit<T>; N]> for MaybeUninit<[T; N]> {
#[inline(always)]
fn as_mut(&mut self) -> &mut [MaybeUninit<T>; N] {
// SAFETY: T and MaybeUninit<T> have the same layout
unsafe { &mut *(self as *mut MaybeUninit<[T; N]> as *mut [MaybeUninit<T>; N]) }
}
}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T, const N: usize> AsMut<[MaybeUninit<T>]> for MaybeUninit<[T; N]> {
#[inline(always)]
fn as_mut(&mut self) -> &mut [MaybeUninit<T>] {
&mut *AsMut::<[MaybeUninit<T>; N]>::as_mut(self)
}
}

#[stable(feature = "more_conversion_trait_impls", since = "CURRENT_RUSTC_VERSION")]
impl<T, const N: usize> From<MaybeUninit<[T; N]>> for [MaybeUninit<T>; N] {
#[inline(always)]
fn from(arr: MaybeUninit<[T; N]>) -> Self {
arr.transpose()
}
}

impl<T, const N: usize> [MaybeUninit<T>; N] {
/// Transposes a `[MaybeUninit<T>; N]` into a `MaybeUninit<[T; N]>`.
///
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2 changes: 1 addition & 1 deletion tests/ui/suggestions/issue-71394-no-from-impl.stderr
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Expand Up @@ -13,7 +13,7 @@ LL | let _: &[i8] = data.into();
`[T; 6]` implements `From<(T, T, T, T, T, T)>`
`[T; 7]` implements `From<(T, T, T, T, T, T, T)>`
`[T; 8]` implements `From<(T, T, T, T, T, T, T, T)>`
and 6 others
and 7 others
= note: required for `&[u8]` to implement `Into<&[i8]>`

error: aborting due to 1 previous error
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