bevy/crates/bevy_macro_utils
Zachary Harrold 6963b58eba
Modify derive_label to support no_std environments (#15465)
# Objective

- Contributes to #15460

## Solution

- Wrap `derive_label` `quote!` in an anonymous constant which contains
an `extern crate alloc` statement, allowing use of the `alloc` namespace
even when a user has not brought in the crate themselves.

## Testing

- CI passed locally.

## Notes

We can't generate code that uses `::std::boxed::Box` in `no_std`
environments, but we also can't rely on `::alloc::boxed::Box` either,
since the user might not have declared `extern crate alloc`. To resolve
this, the generated code is wrapped in an anonymous constant which
contains the `extern crate alloc` invocation.

This does mean the macro is no longer hygienic against cases where the
user provides an alternate `alloc` crate, however I believe this is an
acceptable compromise.

Additionally, this crate itself doesn't need to be `no_std`, it just
needs to _generate_ `no_std` compatible code.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-09-27 20:23:26 +00:00
..
src Modify derive_label to support no_std environments (#15465) 2024-09-27 20:23:26 +00:00
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
README.md Add README.md to all crates (#13184) 2024-05-02 18:56:00 +00:00

Bevy Macro Utilities

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