Tracking Issue for `integer_casts`

[orlp]

Feature gate: #![feature(integer_casts)]

This is a tracking issue for the addition of saturating, wrapping, checked, unchecked, and strict casts between integer types.

Public API

For each built-in integer type T the following methods are added:

impl T {
    /// Converts `self` to the target integer type, saturating at the nearest edge
    /// of the target type's domain if the value does not lie in within it.
    fn saturating_cast<T: BoundedCastFromInt<Self>>(self) -> T;
    
    /// Converts `self` to the target integer type, wrapping around at the
    /// boundary of the target type.
    fn wrapping_cast<T: BoundedCastFromInt<Self>>(self) -> T;

    /// Converts `self` to the target integer type, returning `None` if the value
    /// does not lie in the target type's domain.
    fn checked_cast<T: CheckedCastFromInt<Self>>(self) -> Option<T>;

    /// Equivalent to `self.checked_cast::<Int>().unwrap()`.
    fn strict_cast<T: CheckedCastFromInt<Self>>(self) -> T;

    /// Equivalent to `self.checked_cast::<Int>().unwrap_unchecked()`.
    unsafe fn unchecked_cast<T: CheckedCastFromInt<Self>>(self) -> T;
}

Steps / History

• ACP: Add missing integer casts libs-team#788
• Implementation: Implement feature integer_casts #157402 (in progress)
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• What should happen to the current unstable narrow/truncate API?
• Should the NonZero types be included?

Footnotes

1. https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html ↩

[orlp]

I can't assign myself but I will try to port the implementation from the int-cast crate to std this week.