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Added assert_unsafe_precondition! check for NonZeroXxx::from_mut_unchecked

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SOFe 2022-10-30 14:49:24 +08:00 committed by David Tolnay
parent 4459be7bd5
commit 3acb445f15
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1 changed files with 20 additions and 13 deletions
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33
library/core/src/num/nonzero.rs
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@ -171,18 +171,6 @@ macro_rules! nonzero_integer {
}
}
/// Converts a primitive mutable reference to a non-zero mutable reference
/// if the referenced integer is not zero.
#[unstable(feature = "nonzero_from_mut", issue = "none")]
#[must_use]
#[inline]
pub fn from_mut(n: &mut $Int) -> Option<&mut Self> {
// SAFETY: Self is repr(transparent), and the value is non-zero.
// As long as the returned reference is alive,
// the user cannot `*n = 0` directly.
(*n != 0).then(|| unsafe { &mut *(n as *mut $Int as *mut Self) })
}
/// Converts a primitive mutable reference to a non-zero mutable reference
/// without checking whether the referenced value is non-zero.
/// This results in undefined behavior if `*n` is zero.
@ -194,7 +182,26 @@ macro_rules! nonzero_integer {
#[inline]
pub unsafe fn from_mut_unchecked(n: &mut $Int) -> &mut Self {
// SAFETY: Self is repr(transparent), and the value is assumed to be non-zero.
unsafe { &mut *(n as *mut $Int as *mut Self) }
unsafe {
let n_alias = &mut *n;
core::intrinsics::assert_unsafe_precondition!(
concat!(stringify!($Ty), "::from_mut_unchecked requires the argument to dereference as non-zero"),
(n_alias: &mut $Int) => *n_alias != 0
);
&mut *(n as *mut $Int as *mut Self)
}
}
/// Converts a primitive mutable reference to a non-zero mutable reference
/// if the referenced integer is not zero.
#[unstable(feature = "nonzero_from_mut", issue = "none")]
#[must_use]
#[inline]
pub fn from_mut(n: &mut $Int) -> Option<&mut Self> {
// SAFETY: Self is repr(transparent), and the value is non-zero.
// As long as the returned reference is alive,
// the user cannot `*n = 0` directly.
(*n != 0).then(|| unsafe { &mut *(n as *mut $Int as *mut Self) })
}
/// Returns the value as a primitive type.