# 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.
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Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>