From f200f792ff13995c58c58f37be8e2effdc8db593 Mon Sep 17 00:00:00 2001
From: Narukara <narukara17@gmail.com>
Date: Wed, 18 Jan 2023 04:02:19 +0800
Subject: [PATCH] remove extern crate statements

---
 src/collections/index.md            | 9 ++++-----
 src/interoperability/c-with-rust.md | 2 --
 src/peripherals/singletons.md       | 3 +--
 3 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/src/collections/index.md b/src/collections/index.md
index 7319a397..aa03666a 100644
--- a/src/collections/index.md
+++ b/src/collections/index.md
@@ -49,9 +49,8 @@ in your program instead of this allocator.
 ``` rust,ignore
 // Bump pointer allocator implementation
 
-extern crate cortex_m;
-
-use core::alloc::GlobalAlloc;
+use core::alloc::{GlobalAlloc, Layout};
+use core::cell::UnsafeCell;
 use core::ptr;
 
 use cortex_m::interrupt;
@@ -144,8 +143,7 @@ as they are exact same implementation.
 allocator. Just `use` its collections and proceed to instantiate them:
 
 ```rust,ignore
-extern crate heapless; // v0.4.x
-
+// heapless version: v0.4.x
 use heapless::Vec;
 use heapless::consts::*;
 
@@ -155,6 +153,7 @@ fn main() -> ! {
 
     xs.push(42).unwrap();
     assert_eq!(xs.pop(), Some(42));
+    loop {}
 }
 ```
 
diff --git a/src/interoperability/c-with-rust.md b/src/interoperability/c-with-rust.md
index d5d8db39..6bec3bd8 100644
--- a/src/interoperability/c-with-rust.md
+++ b/src/interoperability/c-with-rust.md
@@ -125,8 +125,6 @@ For projects with limited dependencies or complexity, or for projects where it i
 In the simplest case of compiling a single C file as a dependency to a static library, an example `build.rs` script using the [`cc` crate] would look like this:
 
 ```rust,ignore
-extern crate cc;
-
 fn main() {
     cc::Build::new()
         .file("foo.c")
diff --git a/src/peripherals/singletons.md b/src/peripherals/singletons.md
index 3f04aa17..1f3a556e 100644
--- a/src/peripherals/singletons.md
+++ b/src/peripherals/singletons.md
@@ -61,8 +61,7 @@ This has a small runtime overhead because we must wrap the `SerialPort` structur
 Although we created our own `Peripherals` structure above, it is not necessary to do this for your code. the `cortex_m` crate contains a macro called `singleton!()` that will perform this action for you.
 
 ```rust,ignore
-#[macro_use(singleton)]
-extern crate cortex_m;
+use cortex_m::singleton;
 
 fn main() {
     // OK if `main` is executed only once