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Rollup merge of #93292 - nvzqz:nonzero-bits, r=dtolnay

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Implement `BITS` constant for non-zero integers

This adds the associated [`BITS`](https://doc.rust-lang.org/stable/std/primitive.usize.html#associatedconstant.BITS) constant to `NonZero{U,I}{8,16,32,64,128,size}`.

This is useful when a type alias refers to either a regular or non-zero integer.
This commit is contained in:
Matthias Krüger 2022-03-13 20:01:58 +01:00 • committed by GitHub
commit 2f9bc56e5a
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1 changed files with 39 additions and 1 deletions
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40
library/core/src/num/nonzero.rs
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@ -465,7 +465,7 @@ macro_rules! nonzero_unsigned_operations {
without modifying the original"]
#[inline]
pub const fn log2(self) -> u32 {
<$Int>::BITS - 1 - self.leading_zeros()
Self::BITS - 1 - self.leading_zeros()
}
/// Returns the base 10 logarithm of the number, rounded down.
@ -1090,3 +1090,41 @@ nonzero_min_max_signed! {
NonZeroI128(i128);
NonZeroIsize(isize);
}
macro_rules! nonzero_bits {
( $( $Ty: ident($Int: ty); )+ ) => {
$(
impl $Ty {
/// The size of this non-zero integer type in bits.
///
#[doc = concat!("This value is equal to [`", stringify!($Int), "::BITS`].")]
///
/// # Examples
///
/// ```
/// #![feature(nonzero_bits)]
#[doc = concat!("# use std::num::", stringify!($Ty), ";")]
///
#[doc = concat!("assert_eq!(", stringify!($Ty), "::BITS, ", stringify!($Int), "::BITS);")]
/// ```
#[unstable(feature = "nonzero_bits", issue = "94881")]
pub const BITS: u32 = <$Int>::BITS;
}
)+
}
}
nonzero_bits! {
NonZeroU8(u8);
NonZeroI8(i8);
NonZeroU16(u16);
NonZeroI16(i16);
NonZeroU32(u32);
NonZeroI32(i32);
NonZeroU64(u64);
NonZeroI64(i64);
NonZeroU128(u128);
NonZeroI128(i128);
NonZeroUsize(usize);
NonZeroIsize(isize);
}