Update docs and tests

src/const_fn.rs

@@ -1,4 +1,7 @@
-
+// Make functions `const` if the `const-fn` feature is active.
+// The meta attributes are in place to keep doc comments with the functions.
+// The function definition incl. annotations and doc comments must be enclodes
+// by the marco invocation.
 macro_rules! const_fn {
     ($(#[$attr:meta])* pub const unsafe fn $($f:tt)*) => (
 

src/lib.rs

@@ -8,21 +8,6 @@
 //! via their type parameter `N`. This means that you can instantiate a `heapless` data structure on
 //! the stack, in a `static` variable, or even in the heap.
 //!
-//! There is a feature gate `const-fn` which enables the nightly `const_fn` feature.
-//! You can enable it in `Cargo.toml`.
-//!
-//! ```text
-//! # Cargo.toml
-//! ...
-//! [dependencies]
-//! heapless = { version = "0.4.0", features = ["const-fn"] }
-//! ...
-//!
-//! ```
-//! When enabled, you can use most `new` methods to initialize `static`
-//! variables at compile time.
-//!
-//!
 //! ```
 //! use heapless::Vec; // fixed capacity `std::Vec`
 //! use heapless::consts::U8; // type level integer used to specify capacity
@@ -38,9 +23,10 @@
 //! // work around
 //! static mut XS: Option<Vec<u8, U8>> = None;
 //! unsafe { XS = Some(Vec::new()) };
+//! let xs = unsafe { XS.as_mut().unwrap() };
 //!
-//! unsafe { XS.as_mut().unwrap().push(42) };
-//! unsafe { assert_eq!(XS.as_mut().unwrap().pop(), Some(42)) };
+//! xs.push(42);
+//! assert_eq!(xs.pop(), Some(42));
 //!
 //! // in the heap (though kind of pointless because no reallocation)
 //! let mut ys: Box<Vec<u8, U8>> = Box::new(Vec::new());
@@ -69,6 +55,29 @@
 //! queue
 //! - [`String`](struct.String.html)
 //! - [`Vec`](struct.Vec.html)
+//!
+//!
+//! In order to target the Rust stable toolchain, there are some feature gates.
+//! The features need to be enabled in `Cargo.toml` in order to use them.
+//! Once the underlaying features in Rust are stable,
+//! these feature gates might be activated by default.
+//!
+//! Example of `Cargo.toml`:
+//!
+//! ```text
+//! ...
+//! [dependencies]
+//! heapless = { version = "0.4.0", features = ["const-fn"] }
+//! ...
+//!
+//! ```
+//!
+//! Currently the following features are availbale and not active by default:
+//!
+//! - `"const-fn"` -- Enable the nightly `const_fn` feature and make most `new` methods `const`.
+//!      This way they can be used to initialize static memory at compile time.
+//!
+
 
 #![allow(warnings)]
 #![deny(missing_docs)]

tests/tsan.rs

@@ -4,7 +4,6 @@ extern crate generic_array;
 extern crate heapless;
 extern crate scoped_threadpool;
 
-#[cfg(feature = "const-fn")]
 use std::thread;
 
 use generic_array::typenum::Unsigned;
@@ -12,12 +11,12 @@ use heapless::consts::*;
 use heapless::RingBuffer;
 use scoped_threadpool::Pool;
 
-#[cfg(feature = "const-fn")]
 #[test]
 fn once() {
-    static mut RB: RingBuffer<i32, U4> = RingBuffer::new();
+    static mut RB: Option<RingBuffer<i32, U4>> = None;
+    unsafe{ RB = Some(RingBuffer::new()) };
 
-    let rb = unsafe { &mut RB };
+    let rb = unsafe { RB.as_mut().unwrap() };
 
     rb.enqueue(0).unwrap();
 
@@ -34,12 +33,12 @@ fn once() {
     });
 }
 
-#[cfg(feature = "const-fn")]
 #[test]
 fn twice() {
-    static mut RB: RingBuffer<i32, U8> = RingBuffer::new();
+    static mut RB: Option<RingBuffer<i32, U4>> = None;
+    unsafe{ RB = Some(RingBuffer::new()) };
 
-    let rb = unsafe { &mut RB };
+    let rb = unsafe { RB.as_mut().unwrap() };
 
     rb.enqueue(0).unwrap();
     rb.enqueue(1).unwrap();