bevy/crates/bevy_ecs/examples/resources.rs
Zachary Harrold d70595b667
Add core and alloc over std Lints (#15281)
# Objective

- Fixes #6370
- Closes #6581

## Solution

- Added the following lints to the workspace:
  - `std_instead_of_core`
  - `std_instead_of_alloc`
  - `alloc_instead_of_core`
- Used `cargo +nightly fmt` with [item level use
formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Item%5C%3A)
to split all `use` statements into single items.
- Used `cargo clippy --workspace --all-targets --all-features --fix
--allow-dirty` to _attempt_ to resolve the new linting issues, and
intervened where the lint was unable to resolve the issue automatically
(usually due to needing an `extern crate alloc;` statement in a crate
root).
- Manually removed certain uses of `std` where negative feature gating
prevented `--all-features` from finding the offending uses.
- Used `cargo +nightly fmt` with [crate level use
formatting](https://rust-lang.github.io/rustfmt/?version=v1.6.0&search=#Crate%5C%3A)
to re-merge all `use` statements matching Bevy's previous styling.
- Manually fixed cases where the `fmt` tool could not re-merge `use`
statements due to conditional compilation attributes.

## Testing

- Ran CI locally

## Migration Guide

The MSRV is now 1.81. Please update to this version or higher.

## Notes

- This is a _massive_ change to try and push through, which is why I've
outlined the semi-automatic steps I used to create this PR, in case this
fails and someone else tries again in the future.
- Making this change has no impact on user code, but does mean Bevy
contributors will be warned to use `core` and `alloc` instead of `std`
where possible.
- This lint is a critical first step towards investigating `no_std`
options for Bevy.

---------

Co-authored-by: François Mockers <francois.mockers@vleue.com>
2024-09-27 00:59:59 +00:00

44 lines
1.1 KiB
Rust

//! In this example we add a counter resource and increase its value in one system,
//! while a different system prints the current count to the console.
#![expect(clippy::std_instead_of_core)]
use bevy_ecs::prelude::*;
use rand::Rng;
use std::ops::Deref;
fn main() {
// Create a world
let mut world = World::new();
// Add the counter resource
world.insert_resource(Counter { value: 0 });
// Create a schedule
let mut schedule = Schedule::default();
// Add systems to increase the counter and to print out the current value
schedule.add_systems((increase_counter, print_counter).chain());
for iteration in 1..=10 {
println!("Simulating frame {iteration}/10");
schedule.run(&mut world);
}
}
// Counter resource to be increased and read by systems
#[derive(Debug, Resource)]
struct Counter {
pub value: i32,
}
fn increase_counter(mut counter: ResMut<Counter>) {
if rand::thread_rng().gen_bool(0.5) {
counter.value += 1;
println!(" Increased counter value");
}
}
fn print_counter(counter: Res<Counter>) {
println!(" {:?}", counter.deref());
}