refactor: minimize cfg needed for no_std, alloc, std features

Author: pchickey

src/async_/spawn.rs

@@ -3,10 +3,7 @@ use core::future::Future;
 use core::mem;
 use core::ptr::{self, NonNull};
 
-#[cfg(all(not(feature = "std"), feature = "alloc"))]
 use alloc::collections::vec_deque::VecDeque;
-#[cfg(feature = "std")]
-use std::collections::vec_deque::VecDeque;
 
 pub use async_task::Task;
 use async_task::{Runnable, ScheduleInfo, WithInfo};

src/core/string.rs

@@ -1,10 +1,9 @@
-#[cfg(all(not(feature = "std"), feature = "alloc"))]
-use alloc::{borrow::Cow, string::String};
 use core::cmp;
 use core::fmt;
 use core::str::{self, Utf8Error};
-#[cfg(feature = "std")]
-use std::{borrow::Cow, string::String};
+
+#[cfg(feature = "alloc")]
+use alloc::{borrow::Cow, string::String};
 
 use crate::ffi::{ngx_str_t, u_char};
 

src/lib.rs

@@ -117,12 +117,8 @@
 //! brew install --with-toolchain llvm
 //! ```
 #![warn(missing_docs)]
-// support both std and no_std
 #![no_std]
-#[cfg(all(not(feature = "std"), feature = "alloc"))]
 extern crate alloc;
-#[cfg(feature = "std")]
-extern crate std;
 
 pub mod allocator;
 #[cfg(feature = "async")]