bevy/crates/bevy_app/Cargo.toml
Zachary Harrold cc69fdd0c6
Add no_std support to bevy (#17955)
# Objective

- Fixes #15460 (will open new issues for further `no_std` efforts)
- Supersedes #17715

## Solution

- Threaded in new features as required
- Made certain crates optional but default enabled
- Removed `compile-check-no-std` from internal `ci` tool since GitHub CI
can now simply check `bevy` itself now
- Added CI task to check `bevy` on `thumbv6m-none-eabi` to ensure
`portable-atomic` support is still valid [^1]

[^1]: This may be controversial, since it could be interpreted as
implying Bevy will maintain support for `thumbv6m-none-eabi` going
forward. In reality, just like `x86_64-unknown-none`, this is a
[canary](https://en.wiktionary.org/wiki/canary_in_a_coal_mine) target to
make it clear when `portable-atomic` no longer works as intended (fixing
atomic support on atomically challenged platforms). If a PR comes
through and makes supporting this class of platforms impossible, then
this CI task can be removed. I however wager this won't be a problem.

## Testing

- CI

---

## Release Notes

Bevy now has support for `no_std` directly from the `bevy` crate.

Users can disable default features and enable a new `default_no_std`
feature instead, allowing `bevy` to be used in `no_std` applications and
libraries.

```toml
# Bevy for `no_std` platforms
bevy = { version = "0.16", default-features = false, features = ["default_no_std"] }
```

`default_no_std` enables certain required features, such as `libm` and
`critical-section`, and as many optional crates as possible (currently
just `bevy_state`). For atomically-challenged platforms such as the
Raspberry Pi Pico, `portable-atomic` will be used automatically.

For library authors, we recommend depending on `bevy` with
`default-features = false` to allow `std` and `no_std` users to both
depend on your crate. Here are some recommended features a library crate
may want to expose:

```toml
[features]
# Most users will be on a platform which has `std` and can use the more-powerful `async_executor`.
default = ["std", "async_executor"]

# Features for typical platforms.
std = ["bevy/std"]
async_executor = ["bevy/async_executor"]

# Features for `no_std` platforms.
libm = ["bevy/libm"]
critical-section = ["bevy/critical-section"]

[dependencies]
# We disable default features to ensure we don't accidentally enable `std` on `no_std` targets, for example. 
bevy = { version = "0.16", default-features = false }
```

While this is verbose, it gives the maximum control to end-users to
decide how they wish to use Bevy on their platform.

We encourage library authors to experiment with `no_std` support. For
libraries relying exclusively on `bevy` and no other dependencies, it
may be as simple as adding `#![no_std]` to your `lib.rs` and exposing
features as above! Bevy can also provide many `std` types, such as
`HashMap`, `Mutex`, and `Instant` on all platforms. See
`bevy::platform_support` for details on what's available out of the box!

## Migration Guide

- If you were previously relying on `bevy` with default features
disabled, you may need to enable the `std` and `async_executor`
features.
- `bevy_reflect` has had its `bevy` feature removed. If you were relying
on this feature, simply enable `smallvec` and `smol_str` instead.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2025-03-07 03:39:46 +00:00

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3.0 KiB
TOML

[package]
name = "bevy_app"
version = "0.16.0-dev"
edition = "2024"
description = "Provides core App functionality for Bevy Engine"
homepage = "https://bevyengine.org"
repository = "https://github.com/bevyengine/bevy"
license = "MIT OR Apache-2.0"
keywords = ["bevy"]
[features]
default = ["std", "bevy_reflect", "bevy_ecs/default", "error_panic_hook"]
# Functionality
## Adds runtime reflection support using `bevy_reflect`.
bevy_reflect = ["dep:bevy_reflect", "bevy_ecs/bevy_reflect"]
## Extends reflection support to functions.
reflect_functions = [
"bevy_reflect",
"bevy_reflect/functions",
"bevy_ecs/reflect_functions",
]
# Debugging Features
## Enables `tracing` integration, allowing spans and other metrics to be reported
## through that framework.
trace = ["dep:tracing"]
## Provides system stepping support, allowing them to be paused, stepped, and
## other debug operations which can help with diagnosing certain behaviors.
bevy_debug_stepping = []
## Will set the BevyError panic hook, which gives cleaner filtered backtraces when
## a BevyError is hit.
error_panic_hook = []
# Platform Compatibility
## Allows access to the `std` crate. Enabling this feature will prevent compilation
## on `no_std` targets, but provides access to certain additional features on
## supported platforms.
std = [
"bevy_reflect?/std",
"bevy_ecs/std",
"dep:ctrlc",
"downcast-rs/std",
"bevy_utils/std",
"bevy_tasks/std",
"bevy_platform_support/std",
]
## `critical-section` provides the building blocks for synchronization primitives
## on all platforms, including `no_std`.
critical-section = [
"bevy_tasks/critical-section",
"bevy_ecs/critical-section",
"bevy_platform_support/critical-section",
"bevy_reflect?/critical-section",
]
[dependencies]
# bevy
bevy_derive = { path = "../bevy_derive", version = "0.16.0-dev" }
bevy_ecs = { path = "../bevy_ecs", version = "0.16.0-dev", default-features = false }
bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", default-features = false, optional = true }
bevy_utils = { path = "../bevy_utils", version = "0.16.0-dev", default-features = false, features = [
"alloc",
] }
bevy_tasks = { path = "../bevy_tasks", version = "0.16.0-dev", default-features = false }
bevy_platform_support = { path = "../bevy_platform_support", version = "0.16.0-dev", default-features = false }
# other
downcast-rs = { version = "2", default-features = false }
thiserror = { version = "2", default-features = false }
variadics_please = "1.1"
tracing = { version = "0.1", default-features = false, optional = true }
log = { version = "0.4", default-features = false }
[target.'cfg(any(unix, windows))'.dependencies]
ctrlc = { version = "3.4.4", optional = true }
[target.'cfg(target_arch = "wasm32")'.dependencies]
wasm-bindgen = { version = "0.2" }
web-sys = { version = "0.3", features = ["Window"] }
console_error_panic_hook = "0.1.6"
[dev-dependencies]
crossbeam-channel = "0.5.0"
[lints]
workspace = true
[package.metadata.docs.rs]
rustdoc-args = ["-Zunstable-options", "--generate-link-to-definition"]
all-features = true