From 4932eb27dfb987f2f540a431bb2e22f50cf358d9 Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Fri, 3 May 2019 14:00:28 +0200
Subject: [PATCH 1/2] use core::mem::MaybeUninit; drop min-const-fn and
 smaller-atomics features

---
 CHANGELOG.md          | 15 ++++++++
 Cargo.toml            | 11 +++---
 ci/script.sh          | 10 ++---
 src/__core.rs         | 54 ---------------------------
 src/binary_heap.rs    | 29 +++++++++------
 src/const_fn.rs       | 33 -----------------
 src/de.rs             | 32 +++++++---------
 src/indexmap.rs       | 69 ++++++++++++----------------------
 src/indexset.rs       | 52 ++++++++++----------------
 src/lib.rs            | 29 ++++-----------
 src/linear_map.rs     | 48 ++++++------------------
 src/pool/mod.rs       | 32 ++++------------
 src/pool/singleton.rs |  8 ++--
 src/sealed.rs         |  8 +---
 src/ser.rs            | 16 +++-----
 src/spsc/mod.rs       | 86 +++++++++++++++++--------------------------
 src/spsc/split.rs     | 24 ++++++------
 src/string.rs         | 20 +++-------
 src/vec.rs            | 35 ++++++------------
 19 files changed, 199 insertions(+), 412 deletions(-)
 delete mode 100644 src/__core.rs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4e18cc71..b9a09a6f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,21 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+## [v0.5.0] - 2019-06-xx
+
+### Removed
+
+- [breaking-change] The "smaller-atomics" feature has been removed. It is now
+  always enabled.
+
+- [breaking-change] The "min-const-fn" feature has been removed. It is now
+  always enabled.
+
+- [breaking-change] The MSRV has been bumped to Rust 1.36.0.
+
+- [breaking-change] The version of the `generic-array` dependency has been
+  bumped to v0.13.0.
+
 ## [v0.4.4] - 2019-05-02
 
 ### Added
diff --git a/Cargo.toml b/Cargo.toml
index 729970f4..f74f9755 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,7 @@ categories = [
 ]
 description = "`static` friendly data structures that don't require dynamic memory allocation"
 documentation = "https://japaric.github.io/heapless/heapless/index.html"
+edition = "2018"
 keywords = [
     "static",
     "no-heap",
@@ -16,19 +17,17 @@ keywords = [
 license = "MIT OR Apache-2.0"
 name = "heapless"
 repository = "https://github.com/japaric/heapless"
-version = "0.4.4"
+version = "0.5.0-alpha.1"
 
 [features]
-const-fn = ["min-const-fn"]
-min-const-fn = []
-smaller-atomics = []
+const-fn = []
 
 [dev-dependencies]
 scoped_threadpool = "0.1.8"
 
 [dependencies]
 as-slice = "0.1.0"
-generic-array = "0.11.0"
+generic-array = "0.13.0"
 hash32 = "0.1.0"
 
 [dependencies.serde]
@@ -37,4 +36,4 @@ optional = true
 default-features = false
 
 [package.metadata.docs.rs]
-features = ["const-fn", "smaller-atomics"]
\ No newline at end of file
+features = ["const-fn"]
\ No newline at end of file
diff --git a/ci/script.sh b/ci/script.sh
index 495e8c09..6665d22a 100644
--- a/ci/script.sh
+++ b/ci/script.sh
@@ -3,7 +3,7 @@ set -euxo pipefail
 main() {
     cargo check --target $TARGET --features 'serde'
     if [ $TRAVIS_RUST_VERSION = nightly ]; then
-        cargo check --target $TARGET --features 'const-fn smaller-atomics'
+        cargo check --target $TARGET --features 'const-fn'
     fi
 
     if [ $TARGET = x86_64-unknown-linux-gnu ]; then
@@ -11,17 +11,17 @@ main() {
         cargo test --target $TARGET --release --features 'serde'
 
         if [ $TRAVIS_RUST_VERSION = nightly ]; then
-            cargo test --target $TARGET --features 'const-fn smaller-atomics'
-            cargo test --target $TARGET --release --features 'const-fn smaller-atomics'
+            cargo test --target $TARGET --features 'const-fn'
+            cargo test --target $TARGET --release --features 'const-fn'
 
             export RUSTFLAGS="-Z sanitizer=thread"
             export RUST_TEST_THREADS=1
             export TSAN_OPTIONS="suppressions=$(pwd)/blacklist.txt"
 
             cargo test --test tsan --target $TARGET
-            cargo test --test tsan --target $TARGET --features 'const-fn smaller-atomics'
+            cargo test --test tsan --target $TARGET --features 'const-fn'
             cargo test --test tsan --target $TARGET --release
-            cargo test --test tsan --target $TARGET --release --features 'const-fn smaller-atomics'
+            cargo test --test tsan --target $TARGET --release --features 'const-fn'
         fi
     fi
 }
diff --git a/src/__core.rs b/src/__core.rs
deleted file mode 100644
index 79d6c538..00000000
--- a/src/__core.rs
+++ /dev/null
@@ -1,54 +0,0 @@
-/// Temporary fork of some stuff in `core` that's doesn't have a `const fn` API
-
-pub mod mem {
-    #[cfg(not(feature = "const-fn"))]
-    pub use core::mem;
-    pub use core::mem::{replace, zeroed, ManuallyDrop};
-
-    // See RFC 1892
-    #[cfg(feature = "const-fn")]
-    pub union MaybeUninit<T> {
-        uninit: (),
-        value: ManuallyDrop<T>,
-    }
-
-    // workaround to get this to compile on stable ("unions with non-`Copy` fields are unstable")
-    #[cfg(not(feature = "const-fn"))]
-    pub struct MaybeUninit<T> {
-        value: ManuallyDrop<T>,
-    }
-
-    impl<T> MaybeUninit<T> {
-        #[cfg(feature = "const-fn")]
-        pub const unsafe fn uninitialized() -> Self {
-            MaybeUninit { uninit: () }
-        }
-
-        #[cfg(not(feature = "const-fn"))]
-        pub unsafe fn uninitialized() -> Self {
-            MaybeUninit {
-                value: ManuallyDrop::new(mem::uninitialized()),
-            }
-        }
-
-        /// Get a reference to the contained value.
-        ///
-        /// # Unsafety
-        ///
-        /// It is up to the caller to guarantee that the the `MaybeUninit` really is in an
-        /// initialized state, otherwise this will immediately cause undefined behavior.
-        pub unsafe fn get_ref(&self) -> &T {
-            &*self.value
-        }
-
-        /// Get a mutable reference to the contained value.
-        ///
-        /// # Unsafety
-        ///
-        /// It is up to the caller to guarantee that the the `MaybeUninit` really is in an
-        /// initialized state, otherwise this will immediately cause undefined behavior.
-        pub unsafe fn get_mut(&mut self) -> &mut T {
-            &mut *self.value
-        }
-    }
-}
diff --git a/src/binary_heap.rs b/src/binary_heap.rs
index 7010037f..7870fed1 100644
--- a/src/binary_heap.rs
+++ b/src/binary_heap.rs
@@ -8,14 +8,17 @@
 // heap can also be converted to a sorted vector in-place, allowing it to be used for an `O(n log
 // n)` in-place heapsort.
 
-use core::cmp::Ordering;
-use core::marker::PhantomData;
-use core::mem::ManuallyDrop;
-use core::{mem, ptr, slice, fmt};
+use core::{
+    cmp::Ordering,
+    fmt,
+    marker::PhantomData,
+    mem::{self, ManuallyDrop},
+    ptr, slice,
+};
 
 use generic_array::ArrayLength;
 
-use Vec;
+use crate::Vec;
 
 /// Min-heap
 pub enum Min {}
@@ -206,7 +209,7 @@ where
     ///
     /// }
     /// ```
-    pub fn iter(&self) -> slice::Iter<T> {
+    pub fn iter(&self) -> slice::Iter<'_, T> {
         self.data.iter()
     }
 
@@ -214,7 +217,7 @@ where
     ///
     /// **WARNING** Mutating the items in the binary heap can leave the heap in an inconsistent
     /// state.
-    pub fn iter_mut(&mut self) -> slice::IterMut<T> {
+    pub fn iter_mut(&mut self) -> slice::IterMut<'_, T> {
         self.data.iter_mut()
     }
 
@@ -344,7 +347,7 @@ where
 /// (because it was moved from or duplicated).
 /// In drop, `Hole` will restore the slice by filling the hole
 /// position with the value that was originally removed.
-struct Hole<'a, T: 'a> {
+struct Hole<'a, T> {
     data: &'a mut [T],
     /// `elt` is always `Some` from new until drop.
     elt: ManuallyDrop<T>,
@@ -441,9 +444,9 @@ impl<T, N, K> fmt::Debug for BinaryHeap<T, N, K>
 where
     N: ArrayLength<T>,
     K: Kind,
-    T: Ord + fmt::Debug
+    T: Ord + fmt::Debug,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_list().entries(self.iter()).finish()
     }
 }
@@ -466,8 +469,10 @@ where
 mod tests {
     use std::vec::Vec;
 
-    use binary_heap::{self, BinaryHeap, Min};
-    use consts::*;
+    use crate::{
+        binary_heap::{self, BinaryHeap, Min},
+        consts::*,
+    };
 
     #[cfg(feature = "const-fn")]
     #[test]
diff --git a/src/const_fn.rs b/src/const_fn.rs
index e962e74d..e4286c64 100644
--- a/src/const_fn.rs
+++ b/src/const_fn.rs
@@ -33,36 +33,3 @@ macro_rules! const_fn {
         fn $($f)*
     );
 }
-
-#[cfg(not(armv6m))]
-macro_rules! min_const_fn {
-    ($(#[$attr:meta])* pub const unsafe fn $($f:tt)*) => (
-
-        $(#[$attr])*
-            #[cfg(feature = "min-const-fn")]
-        pub const unsafe fn $($f)*
-
-            $(#[$attr])*
-            #[cfg(not(feature = "min-const-fn"))]
-        pub unsafe fn $($f)*
-    );
-    ($(#[$attr:meta])* pub const fn $($f:tt)*) => (
-
-        $(#[$attr])*
-            #[cfg(feature = "min-const-fn")]
-        pub const fn $($f)*
-
-            $(#[$attr])*
-            #[cfg(not(feature = "min-const-fn"))]
-        pub fn $($f)*
-    );
-    ($(#[$attr:meta])* const fn $($f:tt)*) => (
-        $(#[$attr])*
-            #[cfg(feature = "min-const-fn")]
-        const fn $($f)*
-
-            $(#[$attr])*
-            #[cfg(not(feature = "min-const-fn"))]
-        fn $($f)*
-    );
-}
diff --git a/src/de.rs b/src/de.rs
index 0ff6029b..9028a11d 100644
--- a/src/de.rs
+++ b/src/de.rs
@@ -1,18 +1,14 @@
-use core::fmt;
-use core::marker::PhantomData;
+use core::{fmt, marker::PhantomData};
 
 use generic_array::{typenum::PowerOfTwo, ArrayLength};
 use hash32::{BuildHasherDefault, Hash, Hasher};
 use serde::de::{self, Deserialize, Deserializer, Error, MapAccess, SeqAccess};
 
-use super::binary_heap::Kind as BinaryHeapKind;
-use super::indexmap::{Bucket, Pos};
-use BinaryHeap;
-use IndexMap;
-use IndexSet;
-use LinearMap;
-use String;
-use Vec;
+use crate::{
+    binary_heap,
+    indexmap::{Bucket, Pos},
+    BinaryHeap, IndexMap, IndexSet, LinearMap, String, Vec,
+};
 
 // Sequential containers
 
@@ -20,7 +16,7 @@ impl<'de, T, N, KIND> Deserialize<'de> for BinaryHeap<T, N, KIND>
 where
     T: Ord + Deserialize<'de>,
     N: ArrayLength<T>,
-    KIND: BinaryHeapKind,
+    KIND: binary_heap::Kind,
 {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where
@@ -32,11 +28,11 @@ where
         where
             T: Ord + Deserialize<'de>,
             N: ArrayLength<T>,
-            KIND: BinaryHeapKind,
+            KIND: binary_heap::Kind,
         {
             type Value = BinaryHeap<T, N, KIND>;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a sequence")
             }
 
@@ -79,7 +75,7 @@ where
         {
             type Value = IndexSet<T, N, BuildHasherDefault<S>>;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a sequence")
             }
 
@@ -120,7 +116,7 @@ where
         {
             type Value = Vec<T, N>;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a sequence")
             }
 
@@ -167,7 +163,7 @@ where
         {
             type Value = IndexMap<K, V, N, BuildHasherDefault<S>>;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a map")
             }
 
@@ -210,7 +206,7 @@ where
         {
             type Value = LinearMap<K, V, N>;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 formatter.write_str("a map")
             }
 
@@ -251,7 +247,7 @@ where
         {
             type Value = String<N>;
 
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                 write!(
                     formatter,
                     "a string no more than {} bytes long",
diff --git a/src/indexmap.rs b/src/indexmap.rs
index 05cec4cd..e86dc01e 100644
--- a/src/indexmap.rs
+++ b/src/indexmap.rs
@@ -1,15 +1,16 @@
-use core::borrow::Borrow;
-use core::iter::FromIterator;
-use core::num::NonZeroU32;
-use core::{fmt, ops, slice};
-
-use generic_array::typenum::PowerOfTwo;
-use generic_array::{ArrayLength, GenericArray};
+use core::{
+    borrow::Borrow,
+    fmt,
+    iter::FromIterator,
+    mem::{self, MaybeUninit},
+    num::NonZeroU32,
+    ops, slice,
+};
 
+use generic_array::{typenum::PowerOfTwo, ArrayLength, GenericArray};
 use hash32::{BuildHasher, BuildHasherDefault, FnvHasher, Hash, Hasher};
 
-use Vec;
-use __core::mem;
+use crate::Vec;
 
 /// An `IndexMap` using the default FNV hasher
 pub type FnvIndexMap<K, V, N> = IndexMap<K, V, N, BuildHasherDefault<FnvHasher>>;
@@ -102,7 +103,7 @@ where
     fn new() -> Self {
         CoreMap {
             entries: Vec::new(),
-            indices: unsafe { mem::zeroed() },
+            indices: unsafe { MaybeUninit::zeroed().assume_init() },
         }
     }
 
@@ -440,7 +441,7 @@ where
     ///     println!("key: {} val: {}", key, val);
     /// }
     /// ```
-    pub fn iter(&self) -> Iter<K, V> {
+    pub fn iter(&self) -> Iter<'_, K, V> {
         Iter {
             iter: self.core.entries.iter(),
         }
@@ -465,7 +466,7 @@ where
     ///     println!("key: {} val: {}", key, val);
     /// }
     /// ```
-    pub fn iter_mut(&mut self) -> IterMut<K, V> {
+    pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
         IterMut {
             iter: self.core.entries.iter_mut(),
         }
@@ -762,7 +763,7 @@ where
     S: BuildHasher,
     N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_map().entries(self.iter()).finish()
     }
 }
@@ -805,10 +806,8 @@ where
     S: BuildHasher,
     N: ArrayLength<Bucket<K, V>> + ArrayLength<Option<Pos>>,
 {
-
 }
 
-
 impl<K, V, N, S> Extend<(K, V)> for IndexMap<K, V, N, S>
 where
     K: Eq + Hash,
@@ -884,19 +883,11 @@ where
     }
 }
 
-pub struct Iter<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+pub struct Iter<'a, K, V> {
     iter: slice::Iter<'a, Bucket<K, V>>,
 }
 
-impl<'a, K, V> Iterator for Iter<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+impl<'a, K, V> Iterator for Iter<'a, K, V> {
     type Item = (&'a K, &'a V);
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -904,11 +895,7 @@ where
     }
 }
 
-impl<'a, K, V> Clone for Iter<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+impl<'a, K, V> Clone for Iter<'a, K, V> {
     fn clone(&self) -> Self {
         Self {
             iter: self.iter.clone(),
@@ -916,19 +903,11 @@ where
     }
 }
 
-pub struct IterMut<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+pub struct IterMut<'a, K, V> {
     iter: slice::IterMut<'a, Bucket<K, V>>,
 }
 
-impl<'a, K, V> Iterator for IterMut<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+impl<'a, K, V> Iterator for IterMut<'a, K, V> {
     type Item = (&'a K, &'a mut V);
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -954,8 +933,7 @@ mod tests {
 
     use generic_array::typenum::Unsigned;
 
-    use consts::*;
-    use FnvIndexMap;
+    use crate::{consts::*, FnvIndexMap};
 
     #[test]
     fn size() {
@@ -973,14 +951,13 @@ mod tests {
         )
     }
 
-
     #[test]
     fn partial_eq() {
         {
             let mut a: FnvIndexMap<_, _, U4> = FnvIndexMap::new();
             a.insert("k1", "v1").unwrap();
 
-            let mut b: FnvIndexMap<_, _, U4>  = FnvIndexMap::new();
+            let mut b: FnvIndexMap<_, _, U4> = FnvIndexMap::new();
             b.insert("k1", "v1").unwrap();
 
             assert!(a == b);
@@ -991,11 +968,11 @@ mod tests {
         }
 
         {
-            let mut a: FnvIndexMap<_, _, U4>  = FnvIndexMap::new();
+            let mut a: FnvIndexMap<_, _, U4> = FnvIndexMap::new();
             a.insert("k1", "v1").unwrap();
             a.insert("k2", "v2").unwrap();
 
-            let mut b: FnvIndexMap<_, _, U4>  = FnvIndexMap::new();
+            let mut b: FnvIndexMap<_, _, U4> = FnvIndexMap::new();
             b.insert("k2", "v2").unwrap();
             b.insert("k1", "v1").unwrap();
 
diff --git a/src/indexset.rs b/src/indexset.rs
index 395c1ca5..4c80fa17 100644
--- a/src/indexset.rs
+++ b/src/indexset.rs
@@ -1,12 +1,9 @@
-use core::borrow::Borrow;
-use core::fmt;
-use core::iter::FromIterator;
+use core::{borrow::Borrow, fmt, iter::FromIterator};
 
-use generic_array::typenum::PowerOfTwo;
-use generic_array::ArrayLength;
+use generic_array::{typenum::PowerOfTwo, ArrayLength};
 use hash32::{BuildHasher, BuildHasherDefault, FnvHasher, Hash, Hasher};
 
-use indexmap::{self, Bucket, IndexMap, Pos};
+use crate::indexmap::{self, Bucket, IndexMap, Pos};
 
 /// An `IndexSet` using the default FNV hasher
 pub type FnvIndexSet<T, N> = IndexSet<T, N, BuildHasherDefault<FnvHasher>>;
@@ -104,7 +101,7 @@ where
     ///     println!("{}", x);
     /// }
     /// ```
-    pub fn iter(&self) -> Iter<T> {
+    pub fn iter(&self) -> Iter<'_, T> {
         Iter {
             iter: self.map.iter(),
         }
@@ -473,7 +470,7 @@ where
     S: BuildHasher,
     N: ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_set().entries(self.iter()).finish()
     }
 }
@@ -562,17 +559,11 @@ where
     }
 }
 
-pub struct Iter<'a, T>
-where
-    T: 'a,
-{
+pub struct Iter<'a, T> {
     iter: indexmap::Iter<'a, T, ()>,
 }
 
-impl<'a, T> Iterator for Iter<'a, T>
-where
-    T: 'a,
-{
+impl<'a, T> Iterator for Iter<'a, T> {
     type Item = &'a T;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -580,10 +571,7 @@ where
     }
 }
 
-impl<'a, T> Clone for Iter<'a, T>
-where
-    T: 'a,
-{
+impl<'a, T> Clone for Iter<'a, T> {
     fn clone(&self) -> Self {
         Self {
             iter: self.iter.clone(),
@@ -593,9 +581,9 @@ where
 
 pub struct Difference<'a, T, N, S>
 where
-    S: 'a + BuildHasher,
-    T: 'a + Eq + Hash,
-    N: 'a + ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
+    S: BuildHasher,
+    T: Eq + Hash,
+    N: ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
 {
     iter: Iter<'a, T>,
     other: &'a IndexSet<T, N, S>,
@@ -603,9 +591,9 @@ where
 
 impl<'a, T, N, S> Iterator for Difference<'a, T, N, S>
 where
-    S: 'a + BuildHasher,
-    T: 'a + Eq + Hash,
-    N: 'a + ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
+    S: BuildHasher,
+    T: Eq + Hash,
+    N: ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
 {
     type Item = &'a T;
 
@@ -621,9 +609,9 @@ where
 
 pub struct Intersection<'a, T, N, S>
 where
-    S: 'a + BuildHasher,
-    T: 'a + Eq + Hash,
-    N: 'a + ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
+    S: BuildHasher,
+    T: Eq + Hash,
+    N: ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
 {
     iter: Iter<'a, T>,
     other: &'a IndexSet<T, N, S>,
@@ -631,9 +619,9 @@ where
 
 impl<'a, T, N, S> Iterator for Intersection<'a, T, N, S>
 where
-    S: 'a + BuildHasher,
-    T: 'a + Eq + Hash,
-    N: 'a + ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
+    S: BuildHasher,
+    T: Eq + Hash,
+    N: ArrayLength<Bucket<T, ()>> + ArrayLength<Option<Pos>>,
 {
     type Item = &'a T;
 
diff --git a/src/lib.rs b/src/lib.rs
index 336f40cc..eeef37fe 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -57,7 +57,7 @@
 //!
 //! # Minimum Supported Rust Version (MSRV)
 //!
-//! This crate is guaranteed to compile on stable Rust 1.30 and up with its default set of features.
+//! This crate is guaranteed to compile on stable Rust 1.36 and up with its default set of features.
 //! It *might* compile on older versions but that may change in any new patch release.
 //!
 //! # Cargo features
@@ -79,28 +79,14 @@
 //!
 //! - `"const-fn"` -- Enables the nightly `const_fn` and `untagged_unions` features and makes most
 //! `new` methods `const`. This way they can be used to initialize static memory at compile time.
-//!
-//! - `"min-const-fn"` -- Turns `Pool::new` into a const fn and makes the `pool!` macro available.
-//! This bumps the required Rust version to 1.31.0.
-//!
-//! - `"smaller-atomics"` -- Lets you initialize `spsc::Queue`s with smaller head / tail indices
-//! (they default to `usize`), shrinking the overall size of the queue.
 
-#![allow(warnings)]
-#![deny(missing_docs)]
-#![deny(warnings)]
 #![cfg_attr(feature = "const-fn", feature(const_fn))]
-#![cfg_attr(feature = "const-fn", feature(untagged_unions))]
-#![no_std]
-
-extern crate as_slice;
-extern crate generic_array;
-extern crate hash32;
-#[cfg(test)]
-extern crate std;
-
-#[cfg(feature = "serde")]
-extern crate serde;
+#![cfg_attr(not(test), no_std)]
+#![deny(missing_docs)]
+#![deny(rust_2018_compatibility)]
+#![deny(rust_2018_idioms)]
+#![deny(warnings)]
+#![feature(maybe_uninit)]
 
 #[macro_use]
 mod const_fn;
@@ -131,5 +117,4 @@ pub mod binary_heap;
 pub mod pool;
 pub mod spsc;
 
-mod __core;
 mod sealed;
diff --git a/src/linear_map.rs b/src/linear_map.rs
index 9412e490..24b9d32d 100644
--- a/src/linear_map.rs
+++ b/src/linear_map.rs
@@ -1,10 +1,8 @@
-use core::borrow::Borrow;
-use core::{mem, ops, slice, fmt};
-use core::iter::FromIterator;
+use core::{borrow::Borrow, fmt, iter::FromIterator, mem, ops, slice};
 
 use generic_array::ArrayLength;
 
-use Vec;
+use crate::Vec;
 
 /// A fixed capacity map / dictionary that performs lookups via linear search
 ///
@@ -232,7 +230,7 @@ where
     ///     println!("key: {} val: {}", key, val);
     /// }
     /// ```
-    pub fn iter(&self) -> Iter<K, V> {
+    pub fn iter(&self) -> Iter<'_, K, V> {
         Iter {
             iter: self.buffer.iter(),
         }
@@ -261,7 +259,7 @@ where
     ///     println!("key: {} val: {}", key, val);
     /// }
     /// ```
-    pub fn iter_mut(&mut self) -> IterMut<K, V> {
+    pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
         IterMut {
             iter: self.buffer.iter_mut(),
         }
@@ -370,7 +368,6 @@ where
     N: ArrayLength<(K, V)>,
     K: Borrow<Q> + Eq,
     Q: Eq + ?Sized,
-    V: 'a,
 {
     type Output = V;
 
@@ -384,7 +381,6 @@ where
     N: ArrayLength<(K, V)>,
     K: Borrow<Q> + Eq,
     Q: Eq + ?Sized,
-    V: 'a,
 {
     fn index_mut(&mut self, key: &Q) -> &mut V {
         self.get_mut(key).expect("no entry found for key")
@@ -420,7 +416,7 @@ where
     K: Eq + fmt::Debug,
     V: fmt::Debug,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_map().entries(self.iter()).finish()
     }
 }
@@ -487,19 +483,11 @@ where
     }
 }
 
-pub struct Iter<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+pub struct Iter<'a, K, V> {
     iter: slice::Iter<'a, (K, V)>,
 }
 
-impl<'a, K, V> Iterator for Iter<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+impl<'a, K, V> Iterator for Iter<'a, K, V> {
     type Item = (&'a K, &'a V);
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -507,11 +495,7 @@ where
     }
 }
 
-impl<'a, K, V> Clone for Iter<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+impl<'a, K, V> Clone for Iter<'a, K, V> {
     fn clone(&self) -> Self {
         Self {
             iter: self.iter.clone(),
@@ -519,19 +503,11 @@ where
     }
 }
 
-pub struct IterMut<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+pub struct IterMut<'a, K, V> {
     iter: slice::IterMut<'a, (K, V)>,
 }
 
-impl<'a, K, V> Iterator for IterMut<'a, K, V>
-where
-    K: 'a,
-    V: 'a,
-{
+impl<'a, K, V> Iterator for IterMut<'a, K, V> {
     type Item = (&'a K, &'a mut V);
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -562,11 +538,9 @@ where
 {
 }
 
-#[cfg(feature = "const-fn")] // Remove this if there are more tests
 #[cfg(test)]
 mod test {
-    use consts::*;
-    use LinearMap;
+    use crate::{consts::*, LinearMap};
 
     #[cfg(feature = "const-fn")]
     #[test]
diff --git a/src/pool/mod.rs b/src/pool/mod.rs
index dd971694..4a8bdd66 100644
--- a/src/pool/mod.rs
+++ b/src/pool/mod.rs
@@ -159,7 +159,6 @@ use core::{
     ptr::{self, NonNull},
     sync::atomic::AtomicPtr,
 };
-
 #[cfg(not(armv6m))]
 use core::{any::TypeId, mem, sync::atomic::Ordering};
 
@@ -185,14 +184,12 @@ unsafe impl<T> Sync for Pool<T> {}
 unsafe impl<T> Send for Pool<T> {}
 
 impl<T> Pool<T> {
-    min_const_fn! {
-        /// Creates a new empty pool
-        pub const fn new() -> Self {
-            Pool {
-                head: AtomicPtr::new(ptr::null_mut()),
+    /// Creates a new empty pool
+    pub const fn new() -> Self {
+        Pool {
+            head: AtomicPtr::new(ptr::null_mut()),
 
-                _not_send_or_sync: PhantomData,
-            }
+            _not_send_or_sync: PhantomData,
         }
     }
 
@@ -386,7 +383,7 @@ impl<T> fmt::Debug for Box<T>
 where
     T: fmt::Debug,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         <T as fmt::Debug>::fmt(self, f)
     }
 }
@@ -395,7 +392,7 @@ impl<T> fmt::Display for Box<T>
 where
     T: fmt::Display,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         <T as fmt::Display>::fmt(self, f)
     }
 }
@@ -454,13 +451,8 @@ mod tests {
     fn grow() {
         static mut MEMORY: [u8; 1024] = [0; 1024];
 
-        #[cfg(feature = "min-const-fn")]
         static POOL: Pool<[u8; 128]> = Pool::new();
 
-        #[allow(non_snake_case)]
-        #[cfg(not(feature = "min-const-fn"))]
-        let POOL: Pool<[u8; 128]> = Pool::new();
-
         unsafe {
             POOL.grow(&mut MEMORY);
         }
@@ -474,13 +466,8 @@ mod tests {
     fn sanity() {
         static mut MEMORY: [u8; 31] = [0; 31];
 
-        #[cfg(feature = "min-const-fn")]
         static POOL: Pool<u8> = Pool::new();
 
-        #[allow(non_snake_case)]
-        #[cfg(not(feature = "min-const-fn"))]
-        let POOL: Pool<u8> = Pool::new();
-
         // empty pool
         assert!(POOL.alloc().is_none());
 
@@ -519,13 +506,8 @@ mod tests {
 
         static mut MEMORY: [u8; 31] = [0; 31];
 
-        #[cfg(feature = "min-const-fn")]
         static POOL: Pool<X> = Pool::new();
 
-        #[allow(non_snake_case)]
-        #[cfg(not(feature = "min-const-fn"))]
-        let POOL: Pool<X> = Pool::new();
-
         POOL.grow(unsafe { &mut MEMORY });
 
         let x = POOL.alloc().unwrap().init(X::new());
diff --git a/src/pool/singleton.rs b/src/pool/singleton.rs
index adb37e33..e15cf480 100644
--- a/src/pool/singleton.rs
+++ b/src/pool/singleton.rs
@@ -15,7 +15,7 @@ use as_slice::{AsMutSlice, AsSlice};
 use super::{Init, Uninit};
 
 /// Instantiates a pool as a global singleton
-#[cfg(all(any(armv7m, test), feature = "min-const-fn"))]
+#[cfg(any(armv7m, test))]
 #[macro_export]
 macro_rules! pool {
     ($ident:ident: $ty:ty) => {
@@ -153,7 +153,7 @@ where
     P: Pool,
     P::Data: fmt::Debug,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         <P::Data as fmt::Debug>::fmt(self, f)
     }
 }
@@ -163,7 +163,7 @@ where
     P: Pool,
     P::Data: fmt::Display,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         <P::Data as fmt::Display>::fmt(self, f)
     }
 }
@@ -270,7 +270,7 @@ where
     }
 }
 
-#[cfg(all(test, feature = "min-const-fn"))]
+#[cfg(test)]
 mod tests {
     use core::{
         mem,
diff --git a/src/sealed.rs b/src/sealed.rs
index fd4e38f4..8309129a 100644
--- a/src/sealed.rs
+++ b/src/sealed.rs
@@ -1,8 +1,6 @@
-use core::sync::atomic::{self, AtomicUsize, Ordering};
-#[cfg(feature = "smaller-atomics")]
-use core::sync::atomic::{AtomicU16, AtomicU8};
+use core::sync::atomic::{self, AtomicU16, AtomicU8, AtomicUsize, Ordering};
 
-use spsc::{MultiCore, SingleCore};
+use crate::spsc::{MultiCore, SingleCore};
 
 pub unsafe trait XCore {
     fn is_multi_core() -> bool;
@@ -38,7 +36,6 @@ pub unsafe trait Uxx: Into<usize> + Send {
         C: XCore;
 }
 
-#[cfg(feature = "smaller-atomics")]
 unsafe impl Uxx for u8 {
     fn truncate(x: usize) -> Self {
         let max = ::core::u8::MAX;
@@ -79,7 +76,6 @@ unsafe impl Uxx for u8 {
     }
 }
 
-#[cfg(feature = "smaller-atomics")]
 unsafe impl Uxx for u16 {
     fn truncate(x: usize) -> Self {
         let max = ::core::u16::MAX;
diff --git a/src/ser.rs b/src/ser.rs
index 085e15ef..60f1b003 100644
--- a/src/ser.rs
+++ b/src/ser.rs
@@ -1,16 +1,12 @@
-use hash32::{BuildHasher, Hash};
-
 use generic_array::{typenum::PowerOfTwo, ArrayLength};
+use hash32::{BuildHasher, Hash};
 use serde::ser::{Serialize, SerializeMap, SerializeSeq, Serializer};
 
-use super::binary_heap::Kind as BinaryHeapKind;
-use super::indexmap::{Bucket, Pos};
-use BinaryHeap;
-use IndexMap;
-use IndexSet;
-use LinearMap;
-use String;
-use Vec;
+use crate::{
+    binary_heap::Kind as BinaryHeapKind,
+    indexmap::{Bucket, Pos},
+    BinaryHeap, IndexMap, IndexSet, LinearMap, String, Vec,
+};
 
 // Sequential containers
 
diff --git a/src/spsc/mod.rs b/src/spsc/mod.rs
index f32d4413..fb7e4278 100644
--- a/src/spsc/mod.rs
+++ b/src/spsc/mod.rs
@@ -1,15 +1,12 @@
 //! Single producer single consumer queue
 
-use core::cell::UnsafeCell;
-use core::marker::PhantomData;
-use core::{ptr, fmt, hash};
+use core::{cell::UnsafeCell, fmt, hash, marker::PhantomData, mem::MaybeUninit, ptr};
 
 use generic_array::{ArrayLength, GenericArray};
 use hash32;
 
-pub use self::split::{Consumer, Producer};
-use __core::mem::MaybeUninit;
-use sealed;
+use crate::sealed;
+pub use split::{Consumer, Producer};
 
 mod split;
 
@@ -176,7 +173,7 @@ where
     }
 
     /// Iterates from the front of the queue to the back
-    pub fn iter(&self) -> Iter<T, N, U, C> {
+    pub fn iter(&self) -> Iter<'_, T, N, U, C> {
         Iter {
             rb: self,
             index: 0,
@@ -185,7 +182,7 @@ where
     }
 
     /// Returns an iterator that allows modifying each value.
-    pub fn iter_mut(&mut self) -> IterMut<T, N, U, C> {
+    pub fn iter_mut(&mut self) -> IterMut<'_, T, N, U, C> {
         let len = self.len_usize();
         IterMut {
             rb: self,
@@ -224,7 +221,7 @@ where
     U: sealed::Uxx,
     C: sealed::XCore,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_list().entries(self.iter()).finish()
     }
 }
@@ -259,7 +256,6 @@ where
     }
 }
 
-
 impl<'a, T, N, U, C> IntoIterator for &'a Queue<T, N, U, C>
 where
     N: ArrayLength<T>,
@@ -298,7 +294,7 @@ macro_rules! impl_ {
                 /// Creates an empty queue with a fixed capacity of `N`
                 pub const fn $uxx() -> Self {
                     Queue {
-                        buffer: unsafe { MaybeUninit::uninitialized() },
+                        buffer: MaybeUninit::uninit(),
                         head: Atomic::new(0),
                         tail: Atomic::new(0),
                     }
@@ -314,7 +310,7 @@ macro_rules! impl_ {
                 /// Creates an empty queue with a fixed capacity of `N` (single core variant)
                 pub const unsafe fn $uxx_sc() -> Self {
                     Queue {
-                        buffer: MaybeUninit::uninitialized(),
+                        buffer: MaybeUninit::uninit(),
                         head: Atomic::new(0),
                         tail: Atomic::new(0),
                     }
@@ -334,10 +330,10 @@ macro_rules! impl_ {
                 let head = self.head.get_mut();
                 let tail = self.tail.get_mut();
 
-                let buffer = unsafe { self.buffer.get_ref() };
+                let p = self.buffer.as_ptr();
 
                 if *head != *tail {
-                    let item = unsafe { ptr::read(buffer.get_unchecked(usize::from(*head % cap))) };
+                    let item = unsafe { (p as *const T).add(usize::from(*head % cap)).read() };
                     *head = head.wrapping_add(1);
                     Some(item)
                 } else {
@@ -373,12 +369,12 @@ macro_rules! impl_ {
                 let cap = self.capacity();
                 let tail = self.tail.get_mut();
 
-                let buffer = self.buffer.get_mut();
-
                 // NOTE(ptr::write) the memory slot that we are about to write to is
                 // uninitialized. We use `ptr::write` to avoid running `T`'s destructor on the
                 // uninitialized memory
-                ptr::write(buffer.get_unchecked_mut(usize::from(*tail % cap)), item);
+                (self.buffer.as_mut_ptr() as *mut T)
+                    .add(usize::from(*tail % cap))
+                    .write(item);
                 *tail = tail.wrapping_add(1);
             }
 
@@ -403,7 +399,7 @@ macro_rules! impl_ {
         {
             fn clone(&self) -> Self {
                 let mut new: Queue<T, N, $uxx, C> = Queue {
-                    buffer: unsafe { MaybeUninit::uninitialized() },
+                    buffer: MaybeUninit::uninit(),
                     head: Atomic::new(0),
                     tail: Atomic::new(0),
                 };
@@ -417,7 +413,6 @@ macro_rules! impl_ {
                 new
             }
         }
-
     };
 }
 
@@ -445,9 +440,7 @@ where
     }
 }
 
-#[cfg(feature = "smaller-atomics")]
 impl_!(u8, u8_sc);
-#[cfg(feature = "smaller-atomics")]
 impl_!(u16, u16_sc);
 impl_!(usize, usize_sc);
 
@@ -463,10 +456,7 @@ where
 {
     fn eq(&self, other: &Queue<T, N2, U2, C2>) -> bool {
         self.len_usize() == other.len_usize()
-            && self
-                .iter()
-                .zip(other.iter())
-                .all(|(v1, v2)| v1 == v2)
+            && self.iter().zip(other.iter()).all(|(v1, v2)| v1 == v2)
     }
 }
 
@@ -477,16 +467,14 @@ where
     U: sealed::Uxx,
     C: sealed::XCore,
 {
-
 }
 
 /// An iterator over the items of a queue
 pub struct Iter<'a, T, N, U, C>
 where
-    N: ArrayLength<T> + 'a,
-    T: 'a,
-    U: 'a + sealed::Uxx,
-    C: 'a + sealed::XCore,
+    N: ArrayLength<T>,
+    U: sealed::Uxx,
+    C: sealed::XCore,
 {
     rb: &'a Queue<T, N, U, C>,
     index: usize,
@@ -495,10 +483,9 @@ where
 
 impl<'a, T, N, U, C> Clone for Iter<'a, T, N, U, C>
 where
-    N: ArrayLength<T> + 'a,
-    T: 'a,
-    U: 'a + sealed::Uxx,
-    C: 'a + sealed::XCore,
+    N: ArrayLength<T>,
+    U: sealed::Uxx,
+    C: sealed::XCore,
 {
     fn clone(&self) -> Self {
         Self {
@@ -512,10 +499,9 @@ where
 /// A mutable iterator over the items of a queue
 pub struct IterMut<'a, T, N, U, C>
 where
-    N: ArrayLength<T> + 'a,
-    T: 'a,
-    U: 'a + sealed::Uxx,
-    C: 'a + sealed::XCore,
+    N: ArrayLength<T>,
+    U: sealed::Uxx,
+    C: sealed::XCore,
 {
     rb: &'a mut Queue<T, N, U, C>,
     index: usize,
@@ -523,13 +509,12 @@ where
 }
 
 macro_rules! iterator {
-    (struct $name:ident -> $elem:ty, $ptr:ty, $asref:ident, $asptr:ident, $mkref:ident) => {
+    (struct $name:ident -> $elem:ty, $ptr:ty, $asptr:ident, $mkref:ident) => {
         impl<'a, T, N, U, C> Iterator for $name<'a, T, N, U, C>
         where
             N: ArrayLength<T>,
-            T: 'a,
-            U: 'a + sealed::Uxx,
-            C: 'a + sealed::XCore,
+            U: sealed::Uxx,
+            C: sealed::XCore,
         {
             type Item = $elem;
 
@@ -538,8 +523,7 @@ macro_rules! iterator {
                     let head = self.rb.head.load_relaxed().into();
 
                     let cap = self.rb.capacity().into();
-                    let buffer = unsafe { self.rb.buffer.$asref() };
-                    let ptr: $ptr = buffer.$asptr();
+                    let ptr = self.rb.buffer.$asptr() as $ptr;
                     let i = (head + self.index) % cap;
                     self.index += 1;
                     Some(unsafe { $mkref!(*ptr.offset(i as isize)) })
@@ -563,15 +547,15 @@ macro_rules! make_ref_mut {
     };
 }
 
-iterator!(struct Iter -> &'a T, *const T, get_ref, as_ptr, make_ref);
-iterator!(struct IterMut -> &'a mut T, *mut T, get_mut, as_mut_ptr, make_ref_mut);
+iterator!(struct Iter -> &'a T, *const T, as_ptr, make_ref);
+iterator!(struct IterMut -> &'a mut T, *mut T, as_mut_ptr, make_ref_mut);
 
 #[cfg(test)]
 mod tests {
-    use consts::*;
-    use spsc::Queue;
     use hash32::Hasher;
 
+    use crate::{consts::*, spsc::Queue};
+
     #[cfg(feature = "const-fn")]
     #[test]
     fn static_new() {
@@ -741,11 +725,7 @@ mod tests {
         let rb2 = rb1.clone();
         assert_eq!(rb1.capacity(), rb2.capacity());
         assert_eq!(rb1.len_usize(), rb2.len_usize());
-        assert!(
-            rb1.iter()
-            .zip(rb2.iter())
-            .all(|(v1, v2)| v1 == v2)
-        );
+        assert!(rb1.iter().zip(rb2.iter()).all(|(v1, v2)| v1 == v2));
     }
 
     #[test]
diff --git a/src/spsc/split.rs b/src/spsc/split.rs
index b8aa2404..c10b56fe 100644
--- a/src/spsc/split.rs
+++ b/src/spsc/split.rs
@@ -1,10 +1,11 @@
-use core::marker::PhantomData;
-use core::ptr::{self, NonNull};
+use core::{marker::PhantomData, ptr::NonNull};
 
 use generic_array::ArrayLength;
 
-use sealed;
-use spsc::{MultiCore, Queue};
+use crate::{
+    sealed,
+    spsc::{MultiCore, Queue},
+};
 
 impl<T, N, U, C> Queue<T, N, U, C>
 where
@@ -110,9 +111,10 @@ macro_rules! impl_ {
                 let rb = self.rb.as_ref();
 
                 let cap = rb.capacity();
-                let buffer = rb.buffer.get_ref();
 
-                let item = ptr::read(buffer.get_unchecked(usize::from(head % cap)));
+                let item = (rb.buffer.as_ptr() as *const T)
+                    .add(usize::from(head % cap))
+                    .read();
                 rb.head.store_release(head.wrapping_add(1)); // ▲
                 item
             }
@@ -177,28 +179,26 @@ macro_rules! impl_ {
                 let rb = self.rb.as_mut();
 
                 let cap = rb.capacity();
-                let buffer = rb.buffer.get_mut();
 
                 // NOTE(ptr::write) the memory slot that we are about to write to is
                 // uninitialized. We use `ptr::write` to avoid running `T`'s destructor on the
                 // uninitialized memory
-                ptr::write(buffer.get_unchecked_mut(usize::from(tail % cap)), item);
+                (rb.buffer.as_mut_ptr() as *mut T)
+                    .add(usize::from(tail % cap))
+                    .write(item);
                 rb.tail.store_release(tail.wrapping_add(1)); // ▲
             }
         }
     };
 }
 
-#[cfg(feature = "smaller-atomics")]
 impl_!(u8);
-#[cfg(feature = "smaller-atomics")]
 impl_!(u16);
 impl_!(usize);
 
 #[cfg(test)]
 mod tests {
-    use consts::*;
-    use spsc::Queue;
+    use crate::{consts::*, spsc::Queue};
 
     #[test]
     fn sanity() {
diff --git a/src/string.rs b/src/string.rs
index b68b0288..83a3d857 100644
--- a/src/string.rs
+++ b/src/string.rs
@@ -1,15 +1,12 @@
-use core::fmt::Write;
-use core::str::Utf8Error;
-use core::{fmt, hash, ops, str};
-
-use hash32;
+use core::{fmt, fmt::Write, hash, ops, str, str::Utf8Error};
 
 use generic_array::{
     typenum::{consts::*, IsGreaterOrEqual},
     ArrayLength,
 };
+use hash32;
 
-use Vec;
+use crate::Vec;
 
 /// A fixed capacity [`String`](https://doc.rust-lang.org/std/string/struct.String.html)
 pub struct String<N>
@@ -444,7 +441,7 @@ impl<N> fmt::Debug for String<N>
 where
     N: ArrayLength<u8>,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let slice: &str = &**self;
         fmt::Debug::fmt(slice, f)
     }
@@ -454,7 +451,7 @@ impl<N> fmt::Display for String<N>
 where
     N: ArrayLength<u8>,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let slice: &str = &**self;
         fmt::Display::fmt(slice, f)
     }
@@ -611,8 +608,7 @@ impl_from_num!(u64, U20);
 
 #[cfg(test)]
 mod tests {
-    use consts::*;
-    use {String, Vec};
+    use crate::{consts::*, String, Vec};
 
     #[cfg(feature = "const-fn")]
     #[test]
@@ -632,8 +628,6 @@ mod tests {
 
     #[test]
     fn debug() {
-        extern crate std;
-
         use core::fmt::Write;
 
         let s: String<U8> = String::from("abcd");
@@ -644,8 +638,6 @@ mod tests {
 
     #[test]
     fn display() {
-        extern crate std;
-
         use core::fmt::Write;
 
         let s: String<U8> = String::from("abcd");
diff --git a/src/vec.rs b/src/vec.rs
index 7f89bcf9..6855982b 100644
--- a/src/vec.rs
+++ b/src/vec.rs
@@ -1,13 +1,8 @@
-use core::{fmt, ops, ptr, slice};
+use core::{fmt, hash, iter::FromIterator, mem::MaybeUninit, ops, ptr, slice};
 
 use generic_array::{ArrayLength, GenericArray};
 use hash32;
 
-use __core::mem::MaybeUninit;
-
-use core::hash;
-use core::iter::FromIterator;
-
 /// A fixed capacity [`Vec`](https://doc.rust-lang.org/std/vec/struct.Vec.html)
 ///
 /// # Examples
@@ -66,7 +61,7 @@ where
         /// Constructs a new, empty vector with a fixed capacity of `N`
         pub const fn new() -> Self {
             Vec {
-                buffer: unsafe { MaybeUninit::uninitialized() },
+                buffer: MaybeUninit::uninit(),
                 len: 0,
             }
         }
@@ -126,11 +121,8 @@ where
     pub(crate) unsafe fn pop_unchecked(&mut self) -> T {
         debug_assert!(!self.is_empty());
 
-        let buffer = self.buffer.get_ref();
-
         self.len -= 1;
-        let item = ptr::read(buffer.get_unchecked(self.len));
-        item
+        (self.buffer.as_ptr() as *const T).add(self.len).read()
     }
 
     /// Appends an `item` to the back of the collection
@@ -146,11 +138,12 @@ where
     }
 
     pub(crate) unsafe fn push_unchecked(&mut self, item: T) {
-        let buffer = self.buffer.get_mut();
-
         // NOTE(ptr::write) the memory slot that we are about to write to is uninitialized. We
         // use `ptr::write` to avoid running `T`'s destructor on the uninitialized memory
-        ptr::write(buffer.get_unchecked_mut(self.len), item);
+        (self.buffer.as_mut_ptr() as *mut T)
+            .add(self.len)
+            .write(item);
+
         self.len += 1;
     }
 
@@ -271,7 +264,7 @@ where
     T: fmt::Debug,
     N: ArrayLength<T>,
 {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let slice: &[T] = &**self;
         slice.fmt(f)
     }
@@ -394,8 +387,7 @@ where
     type Item = T;
     fn next(&mut self) -> Option<Self::Item> {
         if self.next < self.vec.len() {
-            let buffer = unsafe { self.vec.buffer.get_ref() };
-            let item = unsafe { ptr::read(buffer.get_unchecked(self.next)) };
+            let item = unsafe { (self.vec.buffer.as_ptr() as *const T).add(self.next).read() };
             self.next += 1;
             Some(item)
         } else {
@@ -500,10 +492,9 @@ where
     type Target = [T];
 
     fn deref(&self) -> &[T] {
-        let buffer = unsafe { self.buffer.get_ref() };
         // NOTE(unsafe) avoid bound checks in the slicing operation
         // &buffer[..self.len]
-        unsafe { slice::from_raw_parts(buffer.as_ptr(), self.len) }
+        unsafe { slice::from_raw_parts(self.buffer.as_ptr() as *const T, self.len) }
     }
 }
 
@@ -513,11 +504,10 @@ where
 {
     fn deref_mut(&mut self) -> &mut [T] {
         let len = self.len();
-        let buffer = unsafe { self.buffer.get_mut() };
 
         // NOTE(unsafe) avoid bound checks in the slicing operation
         // &mut buffer[..len]
-        unsafe { slice::from_raw_parts_mut(buffer.as_mut_ptr(), len) }
+        unsafe { slice::from_raw_parts_mut(self.buffer.as_mut_ptr() as *mut T, len) }
     }
 }
 
@@ -563,8 +553,7 @@ where
 
 #[cfg(test)]
 mod tests {
-    use consts::*;
-    use Vec;
+    use crate::{consts::*, Vec};
 
     #[cfg(feature = "const-fn")]
     #[test]

From 2a34835f6a8b08e4eb1b1d2bb91a42778bb4540a Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <jorge@japaric.io>
Date: Fri, 3 May 2019 15:56:38 +0200
Subject: [PATCH 2/2] ci: remove non-nightly channels

---
 .travis.yml | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index fceab721..1d74bfac 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,22 +2,10 @@ language: rust
 
 matrix:
   include:
-      # MSRV
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: 1.30.0
-      if: branch != master
-
-    - env: TARGET=x86_64-unknown-linux-gnu
-      rust: stable
-      if: branch != master
-
-    - env: TARGET=thumbv6m-none-eabi
-      rust: beta
-      if: branch != master
-
-    - env: TARGET=thumbv7m-none-eabi
-      rust: stable
-      if: branch != master
+    # TODO MSRV
+    # - env: TARGET=x86_64-unknown-linux-gnu
+    #   rust: 1.36.0
+    #   if: branch != master
 
     - env: TARGET=x86_64-unknown-linux-gnu
       rust: nightly