Use `no_std` but import `std` via `extern crate`
This has the effect of changing the prelude from one containing `std`
item to only `core` ones. This means `Vec` and `Box` need to be imported
explicitly.
// clippy on stable does not know yet about the lint name
// https://github.com/rust-lang/rust-clippy/issues/8560
#![allow(unknown_lints, clippy::only_used_in_recursion)]
+#![no_std]
//! [![crates.io badge](https://img.shields.io/crates/v/serde_with.svg)](https://crates.io/crates/serde_with/)
//! [![Build Status](https://github.com/jonasbb/serde_with/workflows/Rust%20CI/badge.svg)](https://github.com/jonasbb/serde_with)
extern crate alloc;
#[doc(hidden)]
pub extern crate serde;
+extern crate std;
#[cfg(feature = "base64")]
#[cfg_attr(docsrs, doc(cfg(feature = "base64")))]
