Add no_std support to bevy

.github/workflows/ci.yml

@@ -152,7 +152,31 @@ jobs:
       - name: Install Linux dependencies
         uses: ./.github/actions/install-linux-deps
       - name: Check Compile
-        run: cargo run -p ci -- compile-check-no-std
+        run: cargo check -p bevy --no-default-features --features default_no_std --target x86_64-unknown-none
+  check-compiles-no-std-portable-atomic:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    needs: ci
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/
+            crates/bevy_ecs_compile_fail_tests/target/
+            crates/bevy_reflect_compile_fail_tests/target/
+          key: ${{ runner.os }}-cargo-check-compiles-no-std-portable-atomic-${{ hashFiles('**/Cargo.toml') }}
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: thumbv6m-none-eabi
+      - name: Install Linux dependencies
+        uses: ./.github/actions/install-linux-deps
+      - name: Check Compile
+        run: cargo check -p bevy --no-default-features --features default_no_std,portable-atomic --target thumbv6m-none-eabi
 
   build-wasm:
     runs-on: ubuntu-latest

Cargo.toml

@@ -114,6 +114,8 @@ unused_qualifications = "warn"
 
 [features]
 default = [
+  "std",
+  "async_executor",
   "android-game-activity",
   "android_shared_stdcxx",
   "animation",
@@ -124,6 +126,8 @@ default = [
   "bevy_gilrs",
   "bevy_gizmos",
   "bevy_gltf",
+  "bevy_input_focus",
+  "bevy_log",
   "bevy_mesh_picking_backend",
   "bevy_pbr",
   "bevy_picking",
@@ -150,6 +154,9 @@ default = [
   "x11",
 ]
 
+# Recommended defaults for no_std applications
+default_no_std = ["edge_executor", "libm", "critical-section", "bevy_state"]
+
 # Provides an implementation for picking meshes
 bevy_mesh_picking_backend = [
   "bevy_picking",
@@ -257,6 +264,12 @@ bevy_dev_tools = ["bevy_internal/bevy_dev_tools"]
 # Enable the Bevy Remote Protocol
 bevy_remote = ["bevy_internal/bevy_remote"]
 
+# Enable integration with `tracing` and `log`
+bevy_log = ["bevy_internal/bevy_log"]
+
+# Enable input focus subsystem
+bevy_input_focus = ["bevy_internal/bevy_input_focus"]
+
 # Enable passthrough loading for SPIR-V shaders (Only supported on Vulkan, shader capabilities and extensions must agree with the platform implementation)
 spirv_shader_passthrough = ["bevy_internal/spirv_shader_passthrough"]
 
@@ -479,6 +492,24 @@ custom_cursor = ["bevy_internal/custom_cursor"]
 # Experimental support for nodes that are ignored for UI layouting
 ghost_nodes = ["bevy_internal/ghost_nodes"]
 
+# Uses `async-executor` as a task execution backend.
+async_executor = ["std", "bevy_internal/async_executor"]
+
+# Uses `edge-executor` as a task execution backend.
+edge_executor = ["bevy_internal/edge_executor"]
+
+# Allows access to the `std` crate.
+std = ["bevy_internal/std"]
+
+# `critical-section` provides the building blocks for synchronization primitives on all platforms, including `no_std`.
+critical-section = ["bevy_internal/critical-section"]
+
+# `portable-atomic` provides additional platform support for atomic types and operations, even on targets without native support. 
+portable-atomic = ["bevy_internal/portable-atomic"]
+
+# Uses the `libm` maths library instead of the one provided in `std` and `core`.
+libm = ["bevy_internal/libm"]
+
 [dependencies]
 bevy_internal = { path = "crates/bevy_internal", version = "0.16.0-dev", default-features = false }
 tracing = { version = "0.1", default-features = false, optional = true }

crates/bevy_animation/Cargo.toml

@@ -17,7 +17,6 @@ bevy_derive = { path = "../bevy_derive", version = "0.16.0-dev" }
 bevy_log = { path = "../bevy_log", version = "0.16.0-dev" }
 bevy_math = { path = "../bevy_math", version = "0.16.0-dev" }
 bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", features = [
-  "bevy",
   "petgraph",
 ] }
 bevy_render = { path = "../bevy_render", version = "0.16.0-dev" }

crates/bevy_audio/Cargo.toml

@@ -14,9 +14,7 @@ bevy_app = { path = "../bevy_app", version = "0.16.0-dev" }
 bevy_asset = { path = "../bevy_asset", version = "0.16.0-dev" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.16.0-dev" }
 bevy_math = { path = "../bevy_math", version = "0.16.0-dev" }
-bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", features = [
-  "bevy",
-] }
+bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev" }
 bevy_transform = { path = "../bevy_transform", version = "0.16.0-dev" }
 bevy_derive = { path = "../bevy_derive", version = "0.16.0-dev" }
 

crates/bevy_color/Cargo.toml

@@ -13,9 +13,7 @@ rust-version = "1.83.0"
 bevy_math = { path = "../bevy_math", version = "0.16.0-dev", default-features = false, features = [
   "curve",
 ] }
-bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", features = [
-  "bevy",
-], optional = true }
+bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", optional = true }
 bytemuck = { version = "1", features = ["derive"] }
 serde = { version = "1.0", features = [
   "derive",

crates/bevy_ecs/src/entity/unique_slice.rs

@@ -16,10 +16,11 @@ use alloc::{
     boxed::Box,
     collections::VecDeque,
     rc::Rc,
-    sync::Arc,
     vec::Vec,
 };
 
+use bevy_platform_support::sync::Arc;
+
 use super::{
     unique_vec, EntitySet, EntitySetIterator, FromEntitySetIterator, TrustedEntityBorrow,
     UniqueEntityIter, UniqueEntityVec,
@@ -85,9 +86,9 @@ impl<T: TrustedEntityBorrow> UniqueEntitySlice<T> {
     }
 
     /// Casts `self` to the inner slice.
-    pub fn into_arc_inner(self: Arc<Self>) -> Arc<[T]> {
+    pub fn into_arc_inner(this: Arc<Self>) -> Arc<[T]> {
         // SAFETY: UniqueEntitySlice is a transparent wrapper around [T].
-        unsafe { Arc::from_raw(Arc::into_raw(self) as *mut [T]) }
+        unsafe { Arc::from_raw(Arc::into_raw(this) as *mut [T]) }
     }
 
     // Constructs a `UniqueEntitySlice` from a [`Rc<[T]>`] unsafely.

crates/bevy_ecs/src/entity/unique_vec.rs

@@ -12,10 +12,11 @@ use alloc::{
     boxed::Box,
     collections::{BTreeSet, BinaryHeap, TryReserveError, VecDeque},
     rc::Rc,
-    sync::Arc,
     vec::{self, Vec},
 };
 
+use bevy_platform_support::sync::Arc;
+
 use super::{
     unique_slice, EntitySet, FromEntitySetIterator, TrustedEntityBorrow, UniqueEntityIter,
     UniqueEntitySlice,

crates/bevy_gltf/Cargo.toml

@@ -28,9 +28,7 @@ bevy_ecs = { path = "../bevy_ecs", version = "0.16.0-dev" }
 bevy_image = { path = "../bevy_image", version = "0.16.0-dev" }
 bevy_math = { path = "../bevy_math", version = "0.16.0-dev" }
 bevy_pbr = { path = "../bevy_pbr", version = "0.16.0-dev" }
-bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", features = [
-  "bevy",
-] }
+bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev" }
 bevy_render = { path = "../bevy_render", version = "0.16.0-dev" }
 bevy_scene = { path = "../bevy_scene", version = "0.16.0-dev", features = [
   "bevy_render",

crates/bevy_image/Cargo.toml

@@ -49,9 +49,7 @@ bevy_color = { path = "../bevy_color", version = "0.16.0-dev", features = [
   "wgpu-types",
 ] }
 bevy_math = { path = "../bevy_math", version = "0.16.0-dev" }
-bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", features = [
-  "bevy",
-], optional = true }
+bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", optional = true }
 bevy_utils = { path = "../bevy_utils", version = "0.16.0-dev" }
 bevy_platform_support = { path = "../bevy_platform_support", version = "0.16.0-dev", default-features = false, features = [
   "std",

crates/bevy_internal/Cargo.toml

@@ -90,6 +90,7 @@ shader_format_glsl = [
 shader_format_spirv = ["bevy_render/shader_format_spirv"]
 
 serialize = [
+  "bevy_a11y?/serialize",
   "bevy_color?/serialize",
   "bevy_ecs/serialize",
   "bevy_image?/serialize",
@@ -104,12 +105,13 @@ serialize = [
   "bevy_platform_support/serialize",
 ]
 multi_threaded = [
+  "std",
   "bevy_asset?/multi_threaded",
   "bevy_ecs/multi_threaded",
   "bevy_render?/multi_threaded",
   "bevy_tasks/multi_threaded",
 ]
-async-io = ["bevy_tasks/async-io"]
+async-io = ["std", "bevy_tasks/async-io"]
 
 # Display server protocol support (X11 is enabled by default)
 wayland = ["bevy_winit/wayland"]
@@ -272,31 +274,122 @@ custom_cursor = ["bevy_winit/custom_cursor"]
 # Experimental support for nodes that are ignored for UI layouting
 ghost_nodes = ["bevy_ui/ghost_nodes"]
 
+# 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_a11y?/std",
+  "bevy_app/std",
+  "bevy_diagnostic/std",
+  "bevy_ecs/std",
+  "bevy_input/std",
+  "bevy_input_focus?/std",
+  "bevy_math/std",
+  "bevy_platform_support/std",
+  "bevy_reflect/std",
+  "bevy_state?/std",
+  "bevy_time/std",
+  "bevy_transform/std",
+  "bevy_utils/std",
+  "bevy_tasks/std",
+  "bevy_window?/std",
+]
+
+# `critical-section` provides the building blocks for synchronization primitives
+# on all platforms, including `no_std`.
+critical-section = [
+  "bevy_a11y?/critical-section",
+  "bevy_app/critical-section",
+  "bevy_diagnostic/critical-section",
+  "bevy_ecs/critical-section",
+  "bevy_input/critical-section",
+  "bevy_input_focus?/critical-section",
+  "bevy_platform_support/critical-section",
+  "bevy_reflect/critical-section",
+  "bevy_state?/critical-section",
+  "bevy_time/critical-section",
+  "bevy_utils/critical-section",
+  "bevy_tasks/critical-section",
+]
+
+# `portable-atomic` provides additional platform support for atomic types and
+# operations, even on targets without native support. 
+portable-atomic = [
+  "bevy_a11y?/portable-atomic",
+  "bevy_app/portable-atomic",
+  "bevy_diagnostic/portable-atomic",
+  "bevy_ecs/portable-atomic",
+  "bevy_input/portable-atomic",
+  "bevy_input_focus?/portable-atomic",
+  "bevy_platform_support/portable-atomic",
+  "bevy_reflect/portable-atomic",
+  "bevy_state?/portable-atomic",
+  "bevy_time/portable-atomic",
+  "bevy_utils/portable-atomic",
+  "bevy_tasks/portable-atomic",
+]
+
+# Uses the `libm` maths library instead of the one provided in `std` and `core`.
+libm = [
+  "bevy_a11y?/libm",
+  "bevy_input/libm",
+  "bevy_input_focus?/libm",
+  "bevy_math/libm",
+  "bevy_transform/libm",
+  "bevy_window?/libm",
+]
+
+# Executor Backend (choose one)
+# Uses `async-executor` as a task execution backend.
+# This backend is incompatible with `no_std` targets.
+async_executor = ["std", "bevy_tasks/async_executor", "bevy_ecs/async_executor"]
+# Uses `edge-executor` as a task execution backend.
+# Use this instead of `async-executor` if working on a `no_std` target.
+edge_executor = ["bevy_tasks/edge_executor", "bevy_ecs/edge_executor"]
+
 [dependencies]
-# bevy
-bevy_a11y = { path = "../bevy_a11y", version = "0.16.0-dev", optional = true }
-bevy_app = { path = "../bevy_app", version = "0.16.0-dev" }
-bevy_derive = { path = "../bevy_derive", version = "0.16.0-dev" }
-bevy_diagnostic = { path = "../bevy_diagnostic", version = "0.16.0-dev" }
-bevy_ecs = { path = "../bevy_ecs", version = "0.16.0-dev" }
-bevy_state = { path = "../bevy_state", optional = true, version = "0.16.0-dev" }
-bevy_input = { path = "../bevy_input", version = "0.16.0-dev" }
-bevy_input_focus = { path = "../bevy_input_focus", version = "0.16.0-dev" }
-bevy_log = { path = "../bevy_log", version = "0.16.0-dev" }
-bevy_math = { path = "../bevy_math", version = "0.16.0-dev", features = [
+# bevy (no_std)
+bevy_app = { path = "../bevy_app", version = "0.16.0-dev", default-features = false, features = [
+  "bevy_tasks",
+  "bevy_reflect",
+] }
+bevy_derive = { path = "../bevy_derive", version = "0.16.0-dev", default-features = false }
+bevy_diagnostic = { path = "../bevy_diagnostic", version = "0.16.0-dev", default-features = false }
+bevy_ecs = { path = "../bevy_ecs", version = "0.16.0-dev", default-features = false, features = [
+  "bevy_reflect",
+] }
+bevy_input = { path = "../bevy_input", version = "0.16.0-dev", default-features = false, features = [
+  "bevy_reflect",
+] }
+bevy_math = { path = "../bevy_math", version = "0.16.0-dev", default-features = false, features = [
   "bevy_reflect",
 ] }
-bevy_platform_support = { path = "../bevy_platform_support", version = "0.16.0-dev" }
-bevy_ptr = { path = "../bevy_ptr", version = "0.16.0-dev" }
-bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", features = [
-  "bevy",
+bevy_platform_support = { path = "../bevy_platform_support", version = "0.16.0-dev", default-features = false, features = [
+  "alloc",
+] }
+bevy_ptr = { path = "../bevy_ptr", version = "0.16.0-dev", default-features = false }
+bevy_reflect = { path = "../bevy_reflect", version = "0.16.0-dev", default-features = false, features = [
+  "smallvec",
 ] }
-bevy_time = { path = "../bevy_time", version = "0.16.0-dev" }
-bevy_transform = { path = "../bevy_transform", version = "0.16.0-dev" }
-bevy_utils = { path = "../bevy_utils", version = "0.16.0-dev" }
-bevy_window = { path = "../bevy_window", version = "0.16.0-dev", optional = true }
-bevy_tasks = { path = "../bevy_tasks", version = "0.16.0-dev" }
+bevy_time = { path = "../bevy_time", version = "0.16.0-dev", default-features = false, features = [
+  "bevy_reflect",
+] }
+bevy_transform = { path = "../bevy_transform", version = "0.16.0-dev", default-features = false, features = [
+  "bevy-support",
+  "bevy_reflect",
+] }
+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 (std required)
+bevy_log = { path = "../bevy_log", version = "0.16.0-dev", optional = true }
+
 # bevy (optional)
+bevy_a11y = { path = "../bevy_a11y", optional = true, version = "0.16.0-dev", features = [
+  "bevy_reflect",
+] }
 bevy_animation = { path = "../bevy_animation", optional = true, version = "0.16.0-dev" }
 bevy_asset = { path = "../bevy_asset", optional = true, version = "0.16.0-dev" }
 bevy_audio = { path = "../bevy_audio", optional = true, version = "0.16.0-dev" }
@@ -307,14 +400,24 @@ bevy_gilrs = { path = "../bevy_gilrs", optional = true, version = "0.16.0-dev" }
 bevy_gizmos = { path = "../bevy_gizmos", optional = true, version = "0.16.0-dev", default-features = false }
 bevy_gltf = { path = "../bevy_gltf", optional = true, version = "0.16.0-dev" }
 bevy_image = { path = "../bevy_image", optional = true, version = "0.16.0-dev" }
+bevy_input_focus = { path = "../bevy_input_focus", optional = true, version = "0.16.0-dev", default-features = false, features = [
+  "bevy_reflect",
+] }
 bevy_pbr = { path = "../bevy_pbr", optional = true, version = "0.16.0-dev" }
 bevy_picking = { path = "../bevy_picking", optional = true, version = "0.16.0-dev" }
 bevy_remote = { path = "../bevy_remote", optional = true, version = "0.16.0-dev" }
 bevy_render = { path = "../bevy_render", optional = true, version = "0.16.0-dev" }
 bevy_scene = { path = "../bevy_scene", optional = true, version = "0.16.0-dev" }
 bevy_sprite = { path = "../bevy_sprite", optional = true, version = "0.16.0-dev" }
+bevy_state = { path = "../bevy_state", optional = true, version = "0.16.0-dev", default-features = false, features = [
+  "bevy_app",
+  "bevy_reflect",
+] }
 bevy_text = { path = "../bevy_text", optional = true, version = "0.16.0-dev" }
 bevy_ui = { path = "../bevy_ui", optional = true, version = "0.16.0-dev" }
+bevy_window = { path = "../bevy_window", optional = true, version = "0.16.0-dev", default-features = false, features = [
+  "bevy_reflect",
+] }
 bevy_winit = { path = "../bevy_winit", optional = true, version = "0.16.0-dev" }
 
 [lints]

crates/bevy_internal/src/default_plugins.rs

@@ -4,6 +4,7 @@ plugin_group! {
     /// This plugin group will add all the default plugins for a *Bevy* application:
     pub struct DefaultPlugins {
         bevy_app:::PanicHandlerPlugin,
+        #[cfg(feature = "bevy_log")]
         bevy_log:::LogPlugin,
         bevy_app:::TaskPoolPlugin,
         bevy_diagnostic:::FrameCountPlugin,
@@ -17,6 +18,7 @@ plugin_group! {
         bevy_window:::WindowPlugin,
         #[cfg(feature = "bevy_window")]
         bevy_a11y:::AccessibilityPlugin,
+        #[cfg(feature = "std")]
         #[custom(cfg(any(unix, windows)))]
         bevy_app:::TerminalCtrlCHandlerPlugin,
         #[cfg(feature = "bevy_asset")]