# 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.
Follow up to #11057
Implemented suggestions from reviewers from: a simpler
fit_canvas_to_parent leads to an explicit CSS setting to the canvas.
From my understanding, it has do be set after wgpu creation due to wgpu
overriding the canvas width/height:
4400a58470/examples/src/utils.rs (L68-L74)
# Changelog
- Re-enable a `fit_canvas_to_parent`, it's removal from
https://github.com/bevyengine/bevy/pull/11057 was problematic. Still,
its inner working is more simple than before: bevy doesn't handle its
resizing, winit does.
## Migration Guide
- Cancels the migration from
https://github.com/bevyengine/bevy/pull/11057
Improves #11052
# Changelog
- Remove `Window::fit_canvas_to_parent`, as its resizing on wasm now
respects its CSS configuration.
## Migration Guide
- Remove uses of `Window::fit_canvas_to_parent` in favor of CSS
properties, for example:
```css
canvas {
width: 100%;
height: 100%;
}
```
# Objective
- Fix the asset hack for wasm examples so that they work on the website
- Use patches instead of sed for wasm hacks so that it fails explicitly
when they need to be updated
