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Rollup merge of #126042 - davidzeng0:master, r=Amanieu

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Implement `unsigned_signed_diff`

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Implements https://github.com/rust-lang/rust/issues/126041
This commit is contained in:
Matthias Krüger 2024-07-24 22:22:15 +02:00 • committed by GitHub
commit 7fac549ff1
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1 changed files with 61 additions and 0 deletions
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61
library/core/src/num/uint_macros.rs
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@ -765,6 +765,67 @@ macro_rules! uint_impl {
}
}
#[doc = concat!(
"Checked integer subtraction. Computes `self - rhs` and checks if the result fits into an [`",
stringify!($SignedT), "`], returning `None` if overflow occurred."
)]
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(unsigned_signed_diff)]
#[doc = concat!("assert_eq!(10", stringify!($SelfT), ".checked_signed_diff(2), Some(8));")]
#[doc = concat!("assert_eq!(2", stringify!($SelfT), ".checked_signed_diff(10), Some(-8));")]
#[doc = concat!(
"assert_eq!(",
stringify!($SelfT),
"::MAX.checked_signed_diff(",
stringify!($SignedT),
"::MAX as ",
stringify!($SelfT),
"), None);"
)]
#[doc = concat!(
"assert_eq!((",
stringify!($SignedT),
"::MAX as ",
stringify!($SelfT),
").checked_signed_diff(",
stringify!($SelfT),
"::MAX), Some(",
stringify!($SignedT),
"::MIN));"
)]
#[doc = concat!(
"assert_eq!((",
stringify!($SignedT),
"::MAX as ",
stringify!($SelfT),
" + 1).checked_signed_diff(0), None);"
)]
#[doc = concat!(
"assert_eq!(",
stringify!($SelfT),
"::MAX.checked_signed_diff(",
stringify!($SelfT),
"::MAX), Some(0));"
)]
/// ```
#[unstable(feature = "unsigned_signed_diff", issue = "126041")]
#[inline]
pub const fn checked_signed_diff(self, rhs: Self) -> Option<$SignedT> {
let res = self.wrapping_sub(rhs) as $SignedT;
let overflow = (self >= rhs) == (res < 0);
if !overflow {
Some(res)
} else {
None
}
}
/// Checked integer multiplication. Computes `self * rhs`, returning
/// `None` if overflow occurred.
///