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Tracking Issue for int_roundings #88581
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on Sep 2, 2021 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 failedReacted by Catena cyber, Darius Telyčėnas, Christos Papadopoulos, Hakim, casellimarco, Squirrel and Michael PfaffReacted by 1devNdogsThat is considered acceptable breakage. Per RFC 1105, adding an inherent impl is a minor change.
Reacted by Oscar Rainford, Christos Papadopoulos, kepexx, Ricardo Fernández Serrata and Ľubomír Kurčák- added 3 commits that reference this issue
on Sep 3, 2021 - added a commit that references this issue
on Sep 3, 2021 210 remaining items
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on Sep 10, 2024 - added a commit that references this issue
on Sep 25, 2024 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 todiv_*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.
Reacted by Louis Maddox, Shaun Jackman, Nurzhan Saken, Lucky_Cat, may, Ray Redondo, Esteban Kuber and Hans BrendeIs there something that keeps this feature from being stabilized?
Reacted by Matthias Fauconneau, Ruifeng Xie, Sean Dewar and Zhan RongruiThe signed methods are still unstable too.
While
prev_multiple_ofcan 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.Reacted by rktaxeWhile
prev_multiple_ofcan 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 ina.prev_multiple_of(b.unsigned_abs())- added a commit that references this issue
on Apr 30, 2026 - added a commit that references this issue
on Sep 11, 2026
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Feature gate:
#![feature(int_roundings)]This is a tracking issue for the
div_floor,div_ceil,next_multiple_of, andchecked_multiple_ofmethods on all integer types.Public API
Steps / History
int_roundingsmethods from feedback #95359int_roundings#94455Unresolved Questions