bevy/tools/example-showcase
Zachary Harrold 0403948aa2
Remove Implicit std Prelude from no_std Crates (#17086)
# Background

In `no_std` compatible crates, there is often an `std` feature which
will allow access to the standard library. Currently, with the `std`
feature _enabled_, the
[`std::prelude`](https://doc.rust-lang.org/std/prelude/index.html) is
implicitly imported in all modules. With the feature _disabled_, instead
the [`core::prelude`](https://doc.rust-lang.org/core/prelude/index.html)
is implicitly imported. This creates a subtle and pervasive issue where
`alloc` items _may_ be implicitly included (if `std` is enabled), or
must be explicitly included (if `std` is not enabled).

# Objective

- Make the implicit imports for `no_std` crates consistent regardless of
what features are/not enabled.

## Solution

- Replace the `cfg_attr` "double negative" `no_std` attribute with
conditional compilation to _include_ `std` as an external crate.
```rust
// Before
#![cfg_attr(not(feature = "std"), no_std)]

// After
#![no_std]

#[cfg(feature = "std")]
extern crate std;
```
- Fix imports that are currently broken but are only now visible with
the above fix.

## Testing

- CI

## Notes

I had previously used the "double negative" version of `no_std` based on
general consensus that it was "cleaner" within the Rust embedded
community. However, this implicit prelude issue likely was considered
when forming this consensus. I believe the reason why is the items most
affected by this issue are provided by the `alloc` crate, which is
rarely used within embedded but extensively used within Bevy.
2025-01-03 01:58:43 +00:00
..
src Prefer Display over Debug (#16112) 2024-12-27 00:40:06 +00:00
asset-source-website.patch
Cargo.toml Generate links to definition in source code pages on docs.rs and dev-docs.bevyengine.org (#12965) 2024-07-29 23:10:16 +00:00
disable-audio.patch Add ability to mute audio sinks (#16813) 2024-12-15 19:19:16 +00:00
extra-window-resized-events.patch fix: upgrade to winit v0.30 (#13366) 2024-06-03 13:06:48 +00:00
fixed-window-position.patch Fix window position patch (#14745) 2024-08-15 13:55:15 +00:00
reduce-light-cluster-config.patch Regenerate light cluster patch file (#13655) 2024-06-03 18:19:32 +00:00
remove-desktop-app-mode.patch Update hashbrown to 0.15 (#15801) 2024-12-10 19:45:50 +00:00
window-settings-wasm.patch Remove Implicit std Prelude from no_std Crates (#17086) 2025-01-03 01:58:43 +00:00