Add core and alloc over std Lints
#15281
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@@ -10,7 +10,7 @@ keywords = ["game", "engine", "gamedev", "graphics", "bevy"] | |
| license = "MIT OR Apache-2.0" | ||
| repository = "https://github.com/bevyengine/bevy" | ||
| documentation = "https://docs.rs/bevy" | ||
| rust-version = "1.81.0" | ||
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| [workspace] | ||
| exclude = [ | ||
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@@ -45,6 +45,10 @@ ptr_as_ptr = "warn" | |
| ptr_cast_constness = "warn" | ||
| ref_as_ptr = "warn" | ||
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| std_instead_of_core = "warn" | ||
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Member
There was a problem hiding this comment. The downsides I can see are:
As such, before making such a change, it would be good to qualify exactly what it wins us. For example, getting closer to some potential Before merging, I'd want satisfying answers to:
I also question the viability of this effort for things like consoles when the majority of plugins and user code will still target
Contributor
Author
There was a problem hiding this comment. Thanks for taking the time to look at this! As an immediate response, here's what I personally think in regards to those listed downsides:
Agreed, this will affect all contributors for Bevy going forward. However, I believe this is a relatively minor impact, as
This is true, effectively every crate root (
This is true and I don't have a meaningful rebuttal; this will add one layer of indirection between user and contributor code. What I would say is that we already have that for things like
I personally don't have access to any modern console SDKs so I can't comment on the necessity for a
Out of the above 5 crates, Once the above changes are made, I will be able to use Bevy on any platform, including the GameBoy Advance. What's more, I'd be able to use the high level abstractions like systems, queries, and the With the above context, here are my answers to your three questions:
Obviously this excludes other aspects of Bevy, (
To make a crate like
Yes, but I believe this introduces the very inconsistency in Bevy that we'd like to avoid. These lints make no restrictions around what code we write, or even how they're written, only the names of
I see this as a chicken-and-egg problem; Bevy's plugins are
For the modern consoles, definitely, but this would not be viable for anything retro. Additionally, with Bevy relying on the whole I apologise for the long response, especially considering just how large this PR itself is, and I thank you for taking the time to read it!
Member
There was a problem hiding this comment.
I'd like to keep this if possible, I think with
Not long for this world frankly, the ECS folks kinda hate petgraph
Feature-flagging this is fine
Very doable.
Contributor
Author
There was a problem hiding this comment. Ok, to provide some hard evidence for how close These changes allow this application to compile on `Cargo.toml`[package]
name = "bevy_no_std_test"
version = "0.1.0"
edition = "2021"
[dependencies]
bevy_app = { path = "../bevy_app", version = "0.15.0-dev", default-features = false }
bevy_ecs = { path = "../bevy_ecs", version = "0.15.0-dev", default-features = false }
[profile.dev]
opt-level = 3
debug = true
panic = "abort"`main.rs`//! Demonstrates a [`no_std`] Bevy application.
#![allow(unsafe_code)]
#![no_std]
#![no_main]
// Since we don't have access to `std`, and the `core` library can't assume there's
// a global allocator, we have to explicitly include it using `extern crate`.
extern crate alloc;
// Explicitly importing bevy sub-crates because I haven't threaded the `std` feature
// through bevy_internal and then bevy proper.
use bevy_app::prelude::*;
use bevy_ecs::prelude::*;
#[derive(Resource, Default)]
struct MyResource {
hello_world: bool,
}
#[derive(Component)]
struct Player;
fn main() {
App::empty()
.init_resource::<MyResource>()
.add_systems(Update, |my_resource: Res<MyResource>| {
assert_eq!(my_resource.hello_world, false);
})
.add_systems(Startup, |mut commands: Commands| {
commands.spawn(Player);
})
.add_systems(Update, |query: Query<&Player>| {
assert_eq!(query.iter().count(), 1);
})
.run();
}
/// You cannot rely on [`main`] being called for you in a `no_std` environment.
/// The exact name of your start function will depend on the platform you're developing for.
/// It's convention to name this function `_start`, and we use `#[no_mangle]` to ensure
/// the Rust compiler doesn't change this name.
#[no_mangle]
pub extern "C" fn _start() -> ! {
// Our start function is just going to call main, and if main exits we'll
// just loop forever. Quitting in a `no_std` context isn't defined, since
// you might be running on bare-metal hardware without power management!
main();
loop {}
}
/// Bevy requires access to a global allocator, another item which is platform specific
/// and so must be setup manually.
#[global_allocator]
static ALLOCATOR: allocator::Dummy = allocator::Dummy;
/// Obviously _your_ code will never panic. But, Rust still requires setting up
/// a panic handler _just in case_.
#[panic_handler]
fn panic(_info: &core::panic::PanicInfo) -> ! {
loop {}
}
/// Custom allocator for our no_std environment
mod allocator {
use alloc::alloc::{GlobalAlloc, Layout};
use core::ptr::null_mut;
/// This is a demonstration allocator and is _intentionally_ broken.
pub struct Dummy;
unsafe impl GlobalAlloc for Dummy {
unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
null_mut()
}
unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
panic!("dealloc should be never called")
}
}
}After applying the lints in this PR, it's about another 3000 diff-lines to make
Contributor
There was a problem hiding this comment. I think this is a big win for bevy as the core 😉 of the ecosystem for a very small price.
Contributor
Author
There was a problem hiding this comment. Brilliant! I'm going to resolve the merge conflicts now so hopefully this could be merged soon! |
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| std_instead_of_alloc = "warn" | ||
| alloc_instead_of_core = "warn" | ||
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There was a problem hiding this comment. These lints direct Bevy contributors to use |
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| [workspace.lints.rust] | ||
| missing_docs = "warn" | ||
| unexpected_cfgs = { level = "warn", check-cfg = ['cfg(docsrs_dep)'] } | ||
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Required for
core::error::Error