Work around prelude redundant import warnings

    warning: the item `String` is imported redundantly
       --> src/de.rs:8:5
        |
    8   | use alloc::string::String;
        |     ^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here
        |
        = note: `#[warn(unused_imports)]` on by default

    warning: the item `Vec` is imported redundantly
       --> src/de.rs:9:5
        |
    9   | use alloc::vec::Vec;
        |     ^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Vec` is already defined here

    warning: the item `Box` is imported redundantly
       --> src/error.rs:4:5
        |
    4   | use alloc::boxed::Box;
        |     ^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Box` is already defined here

    warning: the item `String` is imported redundantly
       --> src/error.rs:5:21
        |
    5   | use alloc::string::{String, ToString};
        |                     ^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `ToString` is imported redundantly
       --> src/error.rs:5:29
        |
    5   | use alloc::string::{String, ToString};
        |                             ^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `ToString` is already defined here

    warning: the item `String` is imported redundantly
       --> src/map.rs:10:5
        |
    10  | use alloc::string::String;
        |     ^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `indexmap` is imported redundantly
      --> src/map.rs:23:16
       |
    23 | use indexmap::{self, IndexMap};
       |                ^^^^ the item `indexmap` is already defined here
       |
       = note: `#[warn(unused_imports)]` on by default

    warning: the item `String` is imported redundantly
       --> src/ser.rs:5:21
        |
    5   | use alloc::string::{String, ToString};
        |                     ^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `ToString` is imported redundantly
       --> src/ser.rs:5:29
        |
    5   | use alloc::string::{String, ToString};
        |                             ^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `ToString` is already defined here

    warning: the item `Vec` is imported redundantly
       --> src/ser.rs:6:5
        |
    6   | use alloc::vec::Vec;
        |     ^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Vec` is already defined here

    warning: the item `String` is imported redundantly
       --> src/value/mod.rs:95:5
        |
    95  | use alloc::string::String;
        |     ^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `Vec` is imported redundantly
       --> src/value/mod.rs:96:5
        |
    96  | use alloc::vec::Vec;
        |     ^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Vec` is already defined here

    warning: the item `ToOwned` is imported redundantly
       --> src/value/de.rs:5:26
        |
    5   | use alloc::borrow::{Cow, ToOwned};
        |                          ^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `ToOwned` is already defined here

    warning: the item `String` is imported redundantly
       --> src/value/de.rs:6:5
        |
    6   | use alloc::string::String;
        |     ^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `Vec` is imported redundantly
       --> src/value/de.rs:9:24
        |
    9   | use alloc::vec::{self, Vec};
        |                        ^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Vec` is already defined here

    warning: the item `String` is imported redundantly
       --> src/value/from.rs:5:21
        |
    5   | use alloc::string::{String, ToString};
        |                     ^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `ToString` is imported redundantly
       --> src/value/from.rs:5:29
        |
    5   | use alloc::string::{String, ToString};
        |                             ^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `ToString` is already defined here

    warning: the item `Vec` is imported redundantly
       --> src/value/from.rs:6:5
        |
    6   | use alloc::vec::Vec;
        |     ^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Vec` is already defined here

    warning: the item `ToOwned` is imported redundantly
       --> src/value/index.rs:3:5
        |
    3   | use alloc::borrow::ToOwned;
        |     ^^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `ToOwned` is already defined here

    warning: the item `String` is imported redundantly
       --> src/value/index.rs:4:5
        |
    4   | use alloc::string::String;
        |     ^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `String` is imported redundantly
       --> src/value/partial_eq.rs:2:5
        |
    2   | use alloc::string::String;
        |     ^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `ToOwned` is imported redundantly
       --> src/value/ser.rs:4:5
        |
    4   | use alloc::borrow::ToOwned;
        |     ^^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `ToOwned` is already defined here

    warning: the item `String` is imported redundantly
       --> src/value/ser.rs:5:21
        |
    5   | use alloc::string::{String, ToString};
        |                     ^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `String` is already defined here

    warning: the item `ToString` is imported redundantly
       --> src/value/ser.rs:5:29
        |
    5   | use alloc::string::{String, ToString};
        |                             ^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `ToString` is already defined here

    warning: the item `Vec` is imported redundantly
       --> src/value/ser.rs:6:5
        |
    6   | use alloc::vec::Vec;
        |     ^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Vec` is already defined here

    warning: the item `Vec` is imported redundantly
       --> src/read.rs:2:5
        |
    2   | use alloc::vec::Vec;
        |     ^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Vec` is already defined here

    warning: the item `ToString` is imported redundantly
       --> tests/test.rs:46:5
        |
    46  | use std::string::ToString;
        |     ^^^^^^^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `ToString` is already defined here
        |
        = note: `#[warn(unused_imports)]` on by default

    warning: the item `Vec` is imported redundantly
       --> tests/../src/lexical/bignum.rs:6:5
        |
    6   | use alloc::vec::Vec;
        |     ^^^^^^^^^^^^^^^
        |
       ::: nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/prelude/mod.rs:125:13
        |
    125 |     pub use super::v1::*;
        |             --------- the item `Vec` is already defined here
        |
        = note: `#[warn(unused_imports)]` on by default

src/lexical/bignum.rs

@@ -3,6 +3,7 @@
 //! Big integer type definition.
 
 use super::math::*;
+#[allow(unused_imports)]
 use alloc::vec::Vec;
 
 /// Storage for a big integer type.

src/lib.rs

@@ -360,11 +360,14 @@
 #![deny(clippy::question_mark_used)]
 #![allow(non_upper_case_globals)]
 #![deny(missing_docs)]
-#![cfg_attr(not(feature = "std"), no_std)]
+#![no_std]
 #![cfg_attr(docsrs, feature(doc_cfg))]
 
 extern crate alloc;
 
+#[cfg(feature = "std")]
+extern crate std;
+
 #[cfg(feature = "std")]
 #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 #[doc(inline)]

src/map.rs

@@ -20,7 +20,7 @@ use serde::de;
 #[cfg(not(feature = "preserve_order"))]
 use alloc::collections::{btree_map, BTreeMap};
 #[cfg(feature = "preserve_order")]
-use indexmap::{self, IndexMap};
+use indexmap::IndexMap;
 
 /// Represents a JSON key/value type.
 pub struct Map<K, V> {

src/read.rs

@@ -16,6 +16,8 @@ use crate::raw::BorrowedRawDeserializer;
 use crate::raw::OwnedRawDeserializer;
 #[cfg(feature = "raw_value")]
 use serde::de::Visitor;
+#[cfg(all(feature = "raw_value", feature = "std"))]
+use alloc::string::String;
 
 /// Trait used by the deserializer for iterating over input. This is manually
 /// "specialized" for iterating over &[u8]. Once feature(specialization) is

tests/test.rs

@@ -43,7 +43,6 @@ use std::iter;
 use std::marker::PhantomData;
 use std::mem;
 use std::str::FromStr;
-use std::string::ToString;
 use std::{f32, f64};
 use std::{i16, i32, i64, i8};
 use std::{u16, u32, u64, u8};