Updates to random number generation APIs #143710

joshtriplett · 2025-07-09T21:46:41Z

Updates based on discussions about random number generation.

Add comment on RandomSource::fill_bytes about multiple calls, to allow
efficient implementations for random sources that generate a word at a time.
Drop the Random trait in favor of Distribution<T>, which will let people
make calls like random(1..=6), and which allows for future expansion to
non-uniform distributions, as well as floating-point. (For now, this is only
implemented for RangeFull, to get the interface in place. Subsequent PRs
will implement it for other range types.)

This allows efficient implementations for random sources that generate a word at a time.

rustbot · 2025-07-09T21:46:46Z

rustbot has assigned @tgross35.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

joshtriplett · 2025-07-09T21:51:58Z

r? @Amanieu

Amanieu · 2025-07-09T22:46:48Z

r=me once CI passes

This will let people make calls like random(1..=6), and allows for future expansion to non-uniform distributions, as well as floating-point. For now, this is only implemented for `RangeFull`, to get the interface in place. Subsequent commits will implement it for other range types.

rustbot · 2025-07-11T18:14:06Z

The Miri subtree was changed

cc @rust-lang/miri

joshtriplett · 2025-07-11T19:49:36Z

@bors r=Amanieu

bors · 2025-07-11T19:49:39Z

📌 Commit 900aa00 has been approved by Amanieu

It is now in the queue for this repository.

joshtriplett · 2025-07-11T19:49:46Z

@bors rollup

…nieu Updates to random number generation APIs Updates based on discussions about random number generation. - Add comment on `RandomSource::fill_bytes` about multiple calls, to allow efficient implementations for random sources that generate a word at a time. - Drop the `Random` trait in favor of `Distribution<T>`, which will let people make calls like random(1..=6), and which allows for future expansion to non-uniform distributions, as well as floating-point. (For now, this is only implemented for `RangeFull`, to get the interface in place. Subsequent PRs will implement it for other range types.)

Rollup of 15 pull requests Successful merges: - #143554 (slice: Mark `rotate_left`, `rotate_right` unstably const) - #143634 (interpret/allocation: expose init + write_wildcards on a range) - #143710 (Updates to random number generation APIs) - #143774 (constify `From` and `Into`) - #143776 (std: move NuttX to use arc4random for random number generation) - #143778 (Some const_trait_impl test cleanups) - #143782 (Disambiguate between rustc vs std having debug assertions in `run-make-support` and `run-make` tests) - #143791 (Update sysinfo version to `0.36.0`) - #143796 (Fix ICE for parsed attributes with longer path not handled by CheckAttribute) - #143798 (Remove format short command trait) - #143803 (New tracking issues for const_ops and const_cmp) - #143814 (htmldocck: better error messages for some negative directives) - #143817 (Access `wasi_sdk_path` instead of reading environment variable in bootstrap) - #143822 (./x test miri: fix cleaning the miri_ui directory) - #143823 ([COMPILETEST-UNTANGLE 5/N] Test mode adjustments and other assorted cleanups) r? `@ghost` `@rustbot` modify labels: rollup

jieyouxu · 2025-07-13T04:32:16Z

Failed in rollup (#143853 (comment)):

warning: dropping unsupported crate type `dylib` for target `x86_64-fortanix-unknown-sgx`

error[E0432]: unresolved import `crate::random::Random`
 --> library/std/src/sys/pal/sgx/abi/usercalls/mod.rs:5:42
  |
5 | use crate::random::{DefaultRandomSource, Random};
  |                                          ^^^^^^
  |                                          |
  |                                          no `Random` in `random`
  |                                          help: a similar name exists in the module: `random`

error[E0599]: no function or associated item named `random` found for type `i64` in the current scope
   --> library/std/src/sys/pal/sgx/abi/usercalls/mod.rs:182:34
    |
182 |             let deviation = i64::random(&mut DefaultRandomSource).checked_rem(tenth).unwrap_or(0);
    |                                  ^^^^^^ function or associated item not found in `i64`

@bors r-

joshtriplett · 2025-07-13T09:54:56Z

@bors r+ rollup

bors · 2025-07-13T09:54:59Z

📌 Commit 377aa76 has been approved by joshtriplett

It is now in the queue for this repository.

random: Add comment on RandomSource::fill_bytes about multiple calls

4c94798

This allows efficient implementations for random sources that generate a word at a time.

rustbot assigned tgross35 Jul 9, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jul 9, 2025

rustbot assigned Amanieu and unassigned tgross35 Jul 9, 2025