Tracking Issue for int_roundings

Feature gate: #![feature(int_roundings)]

This is a tracking issue for the div_floor, div_ceil, next_multiple_of, and checked_multiple_of methods on all integer types.

Public API

impl {integer} {
    #[unstable]
    pub const fn div_floor(self, rhs: Self) -> Self;
}

impl {signed integer} {
    #[unstable]
    pub const fn div_ceil(self, rhs: Self) -> Self;

    #[unstable]
    pub const fn next_multiple_of(self, rhs: Self) -> Self;

    #[unstable]
    pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self>;
}

impl {unsigned integer} {
    #[stable(since = "1.73.0")]
    pub const fn div_ceil(self, rhs: Self) -> Self;

    #[stable(since = "1.73.0")]
    pub const fn next_multiple_of(self, rhs: Self) -> Self;

    #[stable(since = "1.73.0")]
    pub const fn checked_next_multiple_of(self, rhs: Self) -> Option<Self>;
}

Steps / History

Unresolved Questions

None yet.

Rollup merge of rust-lang#88582 - jhpratt:int_roundings, r=joshtriplett

Auto merge of rust-lang#88596 - m-ou-se:rollup-cidzt4v, r=m-ou-se

Just updated to the latest nightly, looks like this feature breaks the num-bigint crate.

error[E0658]: use of unstable library feature 'int_roundings'

error[E0658]: use of unstable library feature 'int_roundings'
   --> /home/fourbytes/.cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-0.4.1/src/biguint.rs:398:45
    |
398 |                 let root_scale = extra_bits.div_ceil(&n64);
    |                                             ^^^^^^^^
    |
    = note: see issue #88581 <https://github.com/rust-lang/rust/issues/88581> for more information
    = help: add `#![feature(int_roundings)]` to the crate attributes to enable

error[E0308]: mismatched types
   --> /home/fourbytes/.cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-0.4.1/src/biguint.rs:398:54
    |
398 |                 let root_scale = extra_bits.div_ceil(&n64);
    |                                                      ^^^^ expected `u64`, found `&u64`
    |
help: consider removing the borrow
    |
398 -                 let root_scale = extra_bits.div_ceil(&n64);
398 +                 let root_scale = extra_bits.div_ceil(n64);
    |

error[E0658]: use of unstable library feature 'int_roundings'
  --> /home/fourbytes/.cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-0.4.1/src/biguint/convert.rs:70:10
   |
70 |         .div_ceil(&big_digit::BITS.into())
   |          ^^^^^^^^
   |
   = note: see issue #88581 <https://github.com/rust-lang/rust/issues/88581> for more information
   = help: add `#![feature(int_roundings)]` to the crate attributes to enable

error[E0308]: mismatched types
  --> /home/fourbytes/.cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-0.4.1/src/biguint/convert.rs:70:19
   |
70 |         .div_ceil(&big_digit::BITS.into())
   |                   ^^^^^^^^^^^^^^^^^^^^^^^ expected `u64`, found reference
   |
   = note:   expected type `u64`
           found reference `&_`
help: consider removing the borrow
   |
70 -         .div_ceil(&big_digit::BITS.into())
70 +         .div_ceil(big_digit::BITS.into())
   |

error[E0658]: use of unstable library feature 'int_roundings'
   --> /home/fourbytes/.cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-0.4.1/src/biguint/convert.rs:585:10
    |
585 |         .div_ceil(&u64::from(bits))
    |          ^^^^^^^^
    |
    = note: see issue #88581 <https://github.com/rust-lang/rust/issues/88581> for more information
    = help: add `#![feature(int_roundings)]` to the crate attributes to enable

error[E0308]: mismatched types
   --> /home/fourbytes/.cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-0.4.1/src/biguint/convert.rs:585:19
    |
585 |         .div_ceil(&u64::from(bits))
    |                   ^^^^^^^^^^^^^^^^ expected `u64`, found `&u64`
    |
help: consider removing the borrow
    |
585 -         .div_ceil(&u64::from(bits))
585 +         .div_ceil(u64::from(bits))
    |

error[E0658]: use of unstable library feature 'int_roundings'
   --> /home/fourbytes/.cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-0.4.1/src/biguint/convert.rs:613:10
    |
613 |         .div_ceil(&u64::from(bits))
    |          ^^^^^^^^
    |
    = note: see issue #88581 <https://github.com/rust-lang/rust/issues/88581> for more information
    = help: add `#![feature(int_roundings)]` to the crate attributes to enable

error[E0308]: mismatched types
   --> /home/fourbytes/.cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-0.4.1/src/biguint/convert.rs:613:19
    |
613 |         .div_ceil(&u64::from(bits))
    |                   ^^^^^^^^^^^^^^^^ expected `u64`, found `&u64`
    |
help: consider removing the borrow
    |
613 -         .div_ceil(&u64::from(bits))
613 +         .div_ceil(u64::from(bits))
    |

Some errors have detailed explanations: E0308, E0658.
For more information about an error, try `rustc --explain E0308`.
error: could not compile `num-bigint` due to 8 previous errors
warning: build failed, waiting for other jobs to finish...
error: build failed

That is considered acceptable breakage. Per RFC 1105, adding an inherent impl is a minor change.

rust: use explicitily Integer::div_ceil

Merge #219

rust: use explicitily Integer::div_ceil

Auto merge of rust-lang#130002 - orlp:better-div-floor-ceil, r=thomcc

Auto merge of #130002 - orlp:better-div-floor-ceil, r=thomcc

I am interested in this being fleshed out, so I surveyed the methods. The following division/remainder methods are not implemented. For ceiling and floored rounding, there is no rem_* analogues to div_* and none of the versions that control overflow and wrapping. Additionally, there is no Euclidean saturating division or any saturating remainders.

rem_{ceil,floor}
saturating_rem, saturating_{div,rem}_{ceil,euclid,floor}
wrapping_{div,rem}_{ceil,floor}
checked_{div,rem}_{ceil,floor}
overflowing_{div,rem}_{ceil,floor}
strict_{div,rem}_{ceil,floor} (Tracking Issue for arithmetic that panics on overflow (strict_* operations) #118260)

I maintain a document tracking rounding of division and modulo across languages, which may be a useful reference.

Is there something that keeps this feature from being stabilized?

@nxsaken

@nxsaken I for one would strongly recommend we implement rem_floor and rem_ceil as counterparts to the divs. Especially because rem_floor is the remainder you almost always want.

The signed methods are still unstable too.

While prev_multiple_of can be emulated on signed types by passing a negative parameter, that option is not available for unsigned types. Having this method would be useful for e.g. value alignment and is also good API symmetry IMHO.

While prev_multiple_of can be emulated on signed types by passing a negative parameter, that option is not available for unsigned types. Having this method would be useful for e.g. value alignment and is also good API symmetry IMHO.

Consider unsigned_abs(), as in a.prev_multiple_of(b.unsigned_abs())

RES-518: add ceil_div / floor_div — explicit-rounding integer division (

fix(mcp): reverte o div_ceil — eu quebrei codigo que funcionava

fix(claude-bridge): the panel and hover both date and gate on the num…

fix(claude-bridge): a failed usage poll keeps the last good numbers o…

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Tracking Issue for int_roundings #88581

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fourbytes commented on Sep 3, 2021

jhpratt commented on Sep 3, 2021

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thaliaarchi commented on Nov 23, 2024

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ronnodas commented on Aug 4, 2025

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Tracking Issue for `int_roundings` #88581