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Add From trait for NonZero ints to NonZero ints #66479

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Add From trait for NonZero ints to NonZero ints #66479

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0f86431
Add From trait for NonZero ints to NonZero ints
c3st7n Nov 16, 2019
5cc730c
Fix tidy errors
Nov 16, 2019
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77 changes: 77 additions & 0 deletions src/libcore/num/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,83 @@ macro_rules! from_str_radix_nzint_impl {
from_str_radix_nzint_impl! { NonZeroU8 NonZeroU16 NonZeroU32 NonZeroU64 NonZeroU128 NonZeroUsize
NonZeroI8 NonZeroI16 NonZeroI32 NonZeroI64 NonZeroI128 NonZeroIsize }

// Conversion traits for NonZero integer types to wider NonZero types
macro_rules! impl_nz_from_nz {
($Small: ty, $Large: ty, $LargePrimitive: ty, #[$attr:meta], $doc: expr) => {
#[$attr]
#[doc = $doc]
impl From<$Small> for $Large {
#[inline]
fn from(small: $Small) -> $Large {
// SAFETY: we already know a NonZero will not contain a zero
unsafe {
<$Large>::new_unchecked(small.get() as $LargePrimitive)
}
}
}
};
($Small: ty, $Large: ty, $LargePrimitive: ty, #[$attr:meta]) => {
impl_nz_from_nz!($Small,
$Large,
$LargePrimitive,
#[$attr],
concat!("Converts `",
stringify!($Small),
"` to `",
stringify!($Large),
"` losslessly.

```rust
let small = core::num::", stringify!($Small), "::new(5).unwrap();
let big: core::num::", stringify!($Large), " = small.into();
"));
}
}

// NonZeroUnsigned -> NonZeroUnsigned wider
impl_nz_from_nz! { NonZeroU8, NonZeroU16, u16,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU8, NonZeroU32, u32,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU8, NonZeroU64, u64,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU8, NonZeroU128, u128,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU16, NonZeroU32, u32,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU16, NonZeroU64, u64,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU16, NonZeroU128, u128,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU32, NonZeroU64, u64,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU32, NonZeroU128, u128,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroU64, NonZeroU128, u128,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }

// NonZeroSigned -> NonZeroSigned wider
impl_nz_from_nz! { NonZeroI8, NonZeroI16, i16,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI8, NonZeroI32, i32,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI8, NonZeroI64, i64,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI8, NonZeroI128, i128,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI16, NonZeroI32, i32,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI16, NonZeroI64, i64,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI16, NonZeroI128, i128,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI32, NonZeroI64, i64,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI32, NonZeroI128, i128,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }
impl_nz_from_nz! { NonZeroI64, NonZeroI128, i128,
#[unstable(feature = "nonzero_int_to_wider_nonzero_int_lossless_conv", issue = "66196")] }

/// Provides intentionally-wrapped arithmetic on `T`.
///
/// Operations like `+` on `u32` values is intended to never overflow,
Expand Down