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Merged
newpavlov merged 3 commits into from
May 18, 2026
Merged

Add wasm64-unknown-unknown support for wasm_js backend #848

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9e4d127
Add `wasm64-unknown-unknown` support for `wasm_js` backend
newpavlov May 18, 2026
d4d700e
Disable wasm64 test job
newpavlov May 18, 2026
a8620c8
use `target_family = "wasm"`
newpavlov May 18, 2026
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2 changes: 2 additions & 0 deletions .cargo/config.toml
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Original file line number Diff line number Diff line change
@@ -1,6 +1,8 @@
# Allow normal use of "cargo run" and "cargo test" on these wasm32 platforms.
[target.wasm32-unknown-unknown]
runner = 'wasm-bindgen-test-runner'
[target.wasm64-unknown-unknown]
runner = 'wasm-bindgen-test-runner'
[target.wasm32-wasip1]
runner = 'wasmtime'
[target.wasm32-wasip2]
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31 changes: 22 additions & 9 deletions .github/workflows/tests.yml
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Expand Up @@ -294,18 +294,30 @@ jobs:
matrix:
rust:
- {
description: Web,
description: wasm32,
version: stable,
target: wasm32-unknown-unknown,
flags: '-Dwarnings',
args: '--features=std,sys_rng,wasm_js',
}
- {
description: Web with Atomics,
description: wasm32 with Atomics,
version: nightly,
target: wasm32-unknown-unknown,
components: rust-src,
flags: '-Dwarnings -Ctarget-feature=+atomics,+bulk-memory',
args: '--features=std,sys_rng,wasm_js -Zbuild-std=panic_abort,std',
}
# wasm64 support in wasm-pack is currently broken:
# https://github.com/wasm-bindgen/wasm-pack/issues/1576
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@newpavlov newpavlov May 18, 2026 •
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@audreyt
It looks like wasm64 support in wasm-pack is broken. See wasm-bindgen/wasm-pack#1576

Failed CI log: https://github.com/rust-random/getrandom/actions/runs/26048064756/job/76577341062

# - {
# description: wasm64,
# version: nightly,
# target: wasm64-unknown-unknown,
# components: rust-src,
# flags: '-Dwarnings',
# args: '--features=std,sys_rng,wasm_js -Zbuild-std=panic_abort,std',
# }
steps:
- uses: actions/checkout@v6
- uses: dtolnay/rust-toolchain@master
Expand All @@ -315,7 +327,7 @@ jobs:
- name: Install precompiled wasm-pack
shell: bash
run: |
VERSION=v0.13.1
VERSION=v0.15.0
URL=https://github.com/rustwasm/wasm-pack/releases/download/${VERSION}/wasm-pack-${VERSION}-x86_64-unknown-linux-musl.tar.gz
wget -O - $URL | tar -xz --strip-components=1 -C ~/.cargo/bin
wasm-pack --version
Expand All @@ -324,38 +336,39 @@ jobs:
env:
RUSTFLAGS: ${{ matrix.rust.flags }}
RUSTDOCFLAGS: ${{ matrix.rust.flags }}
run: wasm-pack test --node -- ${{ matrix.rust.args }}
run: wasm-pack test --node ${{ matrix.rust.pack_args }} --
--target ${{ matrix.rust.target }} ${{ matrix.rust.args }}
- name: Test (Firefox)
env:
WASM_BINDGEN_USE_BROWSER: 1
RUSTFLAGS: ${{ matrix.rust.flags }}
RUSTDOCFLAGS: ${{ matrix.rust.flags }}
run: wasm-pack test --headless --firefox -- ${{ matrix.rust.args }}
run: wasm-pack test --headless --firefox -- --target ${{ matrix.rust.target }} ${{ matrix.rust.args }}
- name: Test (Chrome)
env:
WASM_BINDGEN_USE_BROWSER: 1
RUSTFLAGS: ${{ matrix.rust.flags }}
RUSTDOCFLAGS: ${{ matrix.rust.flags }}
run: wasm-pack test --headless --chrome -- ${{ matrix.rust.args }}
run: wasm-pack test --headless --chrome -- --target ${{ matrix.rust.target }} ${{ matrix.rust.args }}
- name: Test (dedicated worker)
env:
WASM_BINDGEN_USE_DEDICATED_WORKER: 1
RUSTFLAGS: ${{ matrix.rust.flags }}
RUSTDOCFLAGS: ${{ matrix.rust.flags }}
run: wasm-pack test --headless --firefox -- ${{ matrix.rust.args }}
run: wasm-pack test --headless --firefox -- --target ${{ matrix.rust.target }} ${{ matrix.rust.args }}
- name: Test (shared worker)
env:
WASM_BINDGEN_USE_SHARED_WORKER: 1
RUSTFLAGS: ${{ matrix.rust.flags }}
RUSTDOCFLAGS: ${{ matrix.rust.flags }}
run: wasm-pack test --headless --firefox -- ${{ matrix.rust.args }}
run: wasm-pack test --headless --firefox -- --target ${{ matrix.rust.target }} ${{ matrix.rust.args }}
- name: Test (service worker)
env:
WASM_BINDGEN_USE_SERVICE_WORKER: 1
RUSTFLAGS: ${{ matrix.rust.flags }}
RUSTDOCFLAGS: ${{ matrix.rust.flags }}
# Firefox doesn't support module service workers and therefor can't import scripts
run: wasm-pack test --headless --chrome -- ${{ matrix.rust.args }}
run: wasm-pack test --headless --chrome -- --target ${{ matrix.rust.target }} ${{ matrix.rust.args }}

wasi_p1:
name: WASIp1
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7 changes: 6 additions & 1 deletion CHANGELOG.md
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Expand Up @@ -6,10 +6,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0

## [Unreleased]

- Restore MSRV to 1.85 for wasm32-wasip3 targets. [#824]
### Added
- `wasm64-unknown-unknown` target support for `wasm_js` backend [#848]

### Changed
- Restore MSRV to 1.85 for wasm32-wasip3 targets [#824]

[Unreleased]: https://github.com/rust-random/getrandom/compare/v0.4.2...master
[#824]: https://github.com/rust-random/getrandom/pull/824
[#848]: https://github.com/rust-random/getrandom/pull/848

## [0.4.2] - 2026-03-03

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6 changes: 3 additions & 3 deletions Cargo.toml
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Expand Up @@ -86,11 +86,11 @@ wasip2 = { version = "1", default-features = false }
wasip3 = ">=0.3, <=0.4"

# wasm_js
[target.'cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))'.dependencies]
[target.'cfg(all(target_family = "wasm", any(target_os = "unknown", target_os = "none")))'.dependencies]
wasm-bindgen = { version = "0.2.98", default-features = false, optional = true }
[target.'cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none"), target_feature = "atomics"))'.dependencies]
[target.'cfg(all(target_family = "wasm", any(target_os = "unknown", target_os = "none"), target_feature = "atomics"))'.dependencies]
js-sys = { version = "0.3.77", default-features = false, optional = true }
[target.'cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))'.dev-dependencies]
[target.'cfg(all(target_family = "wasm", any(target_os = "unknown", target_os = "none")))'.dev-dependencies]
wasm-bindgen-test = "0.3"

[lints.rust.unexpected_cfgs]
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10 changes: 5 additions & 5 deletions README.md
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Expand Up @@ -67,16 +67,16 @@ Pull Requests that add support for new targets to `getrandom` are always welcome

### WebAssembly support

This crate fully supports the [WASI] and [Emscripten] targets. However,
the `wasm32-unknown-unknown` target (i.e. the target used by `wasm-pack`)
is not automatically supported since, from the target name alone, we cannot deduce
This crate fully supports the [WASI] and [Emscripten] targets. However, the `wasm32-unknown-unknown`
and `wasm64-unknown-unknown` targets (i.e. the target used by `wasm-pack`)
are not automatically supported since, from the target name alone, we cannot deduce
which JavaScript interface should be used (or if JavaScript is available at all).

We do not include support for this target in the default configuration because our JS backend
We do not include support for these targets in the default configuration because our JS backend
(supporting web browsers, web workers and Node.js v19 or later) requires [`wasm-bindgen`],
**bloating `Cargo.lock`** and **potentially breaking builds** on non-web WASM platforms.

To enable `getrandom`'s functionality on `wasm32-unknown-unknown` using
To enable `getrandom`'s functionality on `wasm32/64-unknown-unknown` using
[`Crypto.getRandomValues`] via [`wasm-bindgen`], enable the `wasm_js` crate feature.

WARNING: We strongly recommend against enabling this feature in libraries (except for tests)
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4 changes: 2 additions & 2 deletions src/backends.rs
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Expand Up @@ -167,14 +167,14 @@ cfg_if! {
} else if #[cfg(all(target_arch = "x86_64", target_env = "sgx"))] {
mod rdrand;
pub use rdrand::*;
} else if #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))] {
} else if #[cfg(all(target_family = "wasm", any(target_os = "unknown", target_os = "none")))] {
cfg_if! {
if #[cfg(feature = "wasm_js")] {
mod wasm_js;
pub use wasm_js::*;
} else {
compile_error!(concat!(
"The wasm32-unknown-unknown targets are not supported by default; \
"The wasm32/64-unknown-unknown are not supported by default; \
you may need to enable the \"wasm_js\" crate feature. \
For more information see: \
https://docs.rs/getrandom/", env!("CARGO_PKG_VERSION"), "/#webassembly-support"
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4 changes: 2 additions & 2 deletions src/backends/wasm_js.rs
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Expand Up @@ -4,10 +4,10 @@ use core::mem::MaybeUninit;

pub use crate::util::{inner_u32, inner_u64};

#[cfg(not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none"))))]
#[cfg(not(all(target_family = "wasm", any(target_os = "unknown", target_os = "none"),)))]
compile_error!("`wasm_js` backend can be enabled only for OS-less WASM targets!");

use wasm_bindgen::{prelude::wasm_bindgen, JsValue};
use wasm_bindgen::{JsValue, prelude::wasm_bindgen};

// Maximum buffer size allowed in `Crypto.getRandomValuesSize` is 65536 bytes.
// See https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
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6 changes: 5 additions & 1 deletion tests/mod.rs
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Expand Up @@ -2,7 +2,11 @@
use core::mem::MaybeUninit;
use getrandom::{fill, fill_uninit};

#[cfg(all(feature = "wasm_js", target_arch = "wasm32", target_os = "unknown"))]
#[cfg(all(
feature = "wasm_js",
target_family = "wasm",
any(target_os = "unknown", target_os = "none"),
))]
use wasm_bindgen_test::wasm_bindgen_test as test;

#[test]
Expand Down