Re-introduce zero copy codec and add minimal polkadot client API which uses linked native runtime (#65)

* client-api type and move duty roster types to primitives

* tuple implementation for slicable

* mild cleanup of deserialization code

* stubs which handle encoding and decoding themselves

* fancier impl_stubs macro

* zero-copy slicable API

* minimal polkadot-client API

* fix WASM API generation

* move native environment stuff to substrate executor

* fix warnings and grumbles

substrate/substrate/client/src/lib.rs

@@ -1,20 +1,20 @@
 // Copyright 2017 Parity Technologies (UK) Ltd.
-// This file is part of Polkadot.
+// This file is part of Substrate.
 
-// Polkadot is free software: you can redistribute it and/or modify
+// Substrate is free software: you can redistribute it and/or modify
 // it under the terms of the GNU General Public License as published by
 // the Free Software Foundation, either version 3 of the License, or
 // (at your option) any later version.
 
-// Polkadot is distributed in the hope that it will be useful,
+// Substrate is distributed in the hope that it will be useful,
 // but WITHOUT ANY WARRANTY; without even the implied warranty of
 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 // GNU General Public License for more details.
 
 // You should have received a copy of the GNU General Public License
-// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
-//! Polkadot Client
+//! Substrate Client
 
 #![warn(missing_docs)]
 
@@ -139,8 +139,9 @@ impl<B, E> Client<B, E> where
 		})
 	}
 
-	fn state_at(&self, id: BlockId) -> error::Result<B::State> {
-		self.backend.state_at(id)
+	/// Get a reference to the state at a given block.
+	pub fn state_at(&self, block: &BlockId) -> error::Result<B::State> {
+		self.backend.state_at(*block)
 	}
 
 	/// Expose backend reference. To be used in tests only
@@ -148,28 +149,33 @@ impl<B, E> Client<B, E> where
 		&self.backend
 	}
 
-	/// Return single storage entry of contract under given address in state in a block of given id.
+	/// Return single storage entry of contract under given address in state in a block of given hash.
 	pub fn storage(&self, id: &BlockId, key: &StorageKey) -> error::Result<StorageData> {
-		Ok(self.state_at(*id)?
+		Ok(self.state_at(id)?
 			.storage(&key.0)
 			.map(|x| StorageData(x.to_vec()))?)
 	}
 
-	/// Execute a call to a contract on top of state in a block of given id.
+	/// Get the code at a given block.
+	pub fn code_at(&self, id: &BlockId) -> error::Result<Vec<u8>> {
+		self.storage(id, &StorageKey(b":code:".to_vec())).map(|data| data.0)
+	}
+
+	/// Execute a call to a contract on top of state in a block of given hash.
 	///
 	/// No changes are made.
 	pub fn call(&self, id: &BlockId, method: &str, call_data: &[u8]) -> error::Result<CallResult> {
-		let state = self.state_at(*id)?;
 		let mut changes = state_machine::OverlayedChanges::default();
+		let state = self.state_at(id)?;
 
-		let _ = state_machine::execute(
+		let return_data = state_machine::execute(
 			&state,
 			&mut changes,
 			&self.executor,
 			method,
 			call_data,
 		)?;
-		Ok(CallResult { return_data: vec![], changes })
+		Ok(CallResult { return_data, changes })
 	}
 
 	/// Queue a block for import.

substrate/substrate/codec/src/lib.rs

@@ -20,6 +20,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(not(feature = "std"), feature(alloc))]
 
+#[cfg_attr(not(feature = "std"), macro_use)]
 extern crate substrate_runtime_std as rstd;
 
 mod endiansensitive;
@@ -28,6 +29,6 @@ mod joiner;
 mod keyedvec;
 
 pub use self::endiansensitive::EndianSensitive;
-pub use self::slicable::{Slicable, NonTrivialSlicable};
+pub use self::slicable::{Input, Slicable, NonTrivialSlicable};
 pub use self::joiner::Joiner;
 pub use self::keyedvec::KeyedVec;

substrate/substrate/codec/src/slicable.rs

@@ -21,13 +21,25 @@ use rstd::vec::Vec;
 use super::joiner::Joiner;
 use super::endiansensitive::EndianSensitive;
 
+/// Trait that allows reading of data into a slice.
+pub trait Input {
+	/// Read into the provided input slice. Returns the number of bytes read.
+	fn read(&mut self, into: &mut [u8]) -> usize;
+}
+
+impl<'a> Input for &'a [u8] {
+	fn read(&mut self, into: &mut [u8]) -> usize {
+		let len = ::rstd::cmp::min(into.len(), self.len());
+		into[..len].copy_from_slice(&self[..len]);
+		*self = &self[len..];
+		len
+	}
+}
+
 /// Trait that allows zero-copy read/write of value-references to/from slices in LE format.
 pub trait Slicable: Sized {
-	/// Attempt to deserialise the value from a slice. Ignore trailing bytes and
-	/// set the slice's start to just after the last byte consumed.
-	///
-	/// If `None` is returned, then the slice should be unmodified.
-	fn from_slice(value: &mut &[u8]) -> Option<Self>;
+	/// Attempt to deserialise the value from input.
+	fn decode<I: Input>(value: &mut I) -> Option<Self>;
 	/// Convert self to an owned vector.
 	fn to_vec(&self) -> Vec<u8> {
 		self.as_slice_then(|s| s.to_vec())
@@ -40,16 +52,19 @@ pub trait Slicable: Sized {
 pub trait NonTrivialSlicable: Slicable {}
 
 impl<T: EndianSensitive> Slicable for T {
-	fn from_slice(value: &mut &[u8]) -> Option<Self> {
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		let size = mem::size_of::<T>();
 		assert!(size > 0, "EndianSensitive can never be implemented for a zero-sized type.");
-		if value.len() >= size {
-			let x: T = unsafe { ::rstd::ptr::read(value.as_ptr() as *const T) };
-			*value = &value[size..];
-			Some(x.from_le())
-		} else {
-			None
+		let mut val: T = unsafe { mem::zeroed() };
+
+		unsafe {
+			let raw: &mut [u8] = slice::from_raw_parts_mut(
+				&mut val as *mut T as *mut u8,
+				size
+			);
+			if input.read(raw) != size { return None }
 		}
+		Some(val.from_le())
 	}
 
 	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
@@ -70,12 +85,15 @@ impl<T: EndianSensitive> Slicable for T {
 }
 
 impl Slicable for Vec<u8> {
-	fn from_slice(value: &mut &[u8]) -> Option<Self> {
-		u32::from_slice(value).map(move |len| {
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
+		u32::decode(input).and_then(move |len| {
 			let len = len as usize;
-			let res = value[..len].to_vec();
-			*value = &value[len..];
-			res
+			let mut vec = vec![0; len];
+			if input.read(&mut vec[..len]) != len {
+				None
+			} else {
+				Some(vec)
+			}
 		})
 	}
 	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
@@ -92,18 +110,60 @@ impl Slicable for Vec<u8> {
 	}
 }
 
+macro_rules! impl_vec_simple_array {
+	($($size:expr),*) => {
+		$(
+			impl<T> Slicable for Vec<[T; $size]>
+				where [T; $size]: EndianSensitive
+			{
+				fn decode<I: Input>(input: &mut I) -> Option<Self> {
+					u32::decode(input).and_then(move |len| {
+						let mut r = Vec::with_capacity(len as usize);
+						for _ in 0..len {
+							r.push(match Slicable::decode(input) {
+								Some(x) => x,
+								None => return None,
+							});
+						}
+
+						Some(r)
+					})
+				}
+
+				fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+					f(&self.to_vec())
+				}
+
+				fn to_vec(&self) -> Vec<u8> {
+					use rstd::iter::Extend;
+
+					let len = self.len();
+					assert!(len <= u32::max_value() as usize, "Attempted to serialize vec with too many elements.");
+
+					let mut r: Vec<u8> = Vec::new().join(&(len as u32));
+					for item in self {
+						r.extend(item.to_vec());
+					}
+					r
+				}
+			}
+		)*
+	}
+}
+
+impl_vec_simple_array!(1, 2, 4, 8, 16, 32, 64);
+
 impl<T: Slicable> NonTrivialSlicable for Vec<T> where Vec<T>: Slicable {}
 
 impl<T: NonTrivialSlicable> Slicable for Vec<T> {
-	fn from_slice(value: &mut &[u8]) -> Option<Self> {
-		u32::from_slice(value).and_then(move |len| {
-			let len = len as usize;
-			let mut r = Vec::with_capacity(len);
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
+		u32::decode(input).and_then(move |len| {
+			let mut r = Vec::with_capacity(len as usize);
 			for _ in 0..len {
-				match T::from_slice(value) {
+				r.push(match T::decode(input) {
+					Some(x) => x,
 					None => return None,
-					Some(v) => r.push(v),
-				}
+				});
 			}
 
 			Some(r)
@@ -128,6 +188,82 @@ impl<T: NonTrivialSlicable> Slicable for Vec<T> {
 	}
 }
 
+impl Slicable for () {
+	fn decode<I: Input>(_: &mut I) -> Option<()> {
+		Some(())
+	}
+
+	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+		f(&[])
+	}
+
+	fn to_vec(&self) -> Vec<u8> {
+		Vec::new()
+	}
+}
+
+macro_rules! tuple_impl {
+	($one:ident,) => {
+		impl<$one: Slicable> Slicable for ($one,) {
+			fn decode<I: Input>(input: &mut I) -> Option<Self> {
+				match $one::decode(input) {
+					None => None,
+					Some($one) => Some(($one,)),
+				}
+			}
+
+			fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
+				self.0.as_slice_then(f)
+			}
+		}
+	};
+	($first:ident, $($rest:ident,)+) => {
+		impl<$first: Slicable, $($rest: Slicable),+>
+		Slicable for
+		($first, $($rest),+) {
+			fn decode<INPUT: Input>(input: &mut INPUT) -> Option<Self> {
+				Some((
+					match $first::decode(input) {
+						Some(x) => x,
+						None => return None,
+					},
+					$(match $rest::decode(input) {
+						Some(x) => x,
+						None => return None,
+					},)+
+				))
+			}
+
+			fn as_slice_then<RETURN, PROCESS>(&self, f: PROCESS) -> RETURN
+				where PROCESS: FnOnce(&[u8]) -> RETURN
+			{
+				let mut v = Vec::new();
+
+				let (
+					ref $first,
+					$(ref $rest),+
+				) = *self;
+
+				$first.as_slice_then(|s| v.extend(s));
+				$($rest.as_slice_then(|s| v.extend(s));)+
+
+				f(v.as_slice())
+			}
+		}
+
+		tuple_impl!($($rest,)+);
+	}
+}
+
+#[allow(non_snake_case)]
+mod inner_tuple_impl {
+	use rstd::vec::Vec;
+
+	use super::{Input, Slicable};
+	tuple_impl!(A, B, C, D, E, F, G, H, I, J, K,);
+}
+
+
 #[cfg(test)]
 mod tests {
 	use super::*;

substrate/substrate/executor/src/lib.rs

@@ -61,4 +61,4 @@ mod native_executor;
 
 pub mod error;
 pub use wasm_executor::WasmExecutor;
-pub use native_executor::{NativeExecutionDispatch, NativeExecutor};
+pub use native_executor::{with_native_environment, NativeExecutor, NativeExecutionDispatch};

substrate/substrate/executor/src/native_executor.rs

@@ -15,11 +15,23 @@
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
 use error::{Error, ErrorKind, Result};
-use runtime_io;
 use state_machine::{Externalities, CodeExecutor};
 use wasm_executor::WasmExecutor;
 
-use std::panic::catch_unwind;
+fn safe_call<F, U>(f: F) -> Result<U>
+	where F: ::std::panic::UnwindSafe + FnOnce() -> U
+{
+	::std::panic::catch_unwind(f).map_err(|_| ErrorKind::Runtime.into())
+}
+
+/// Set up the externalities and safe calling environment to execute calls to a native runtime.
+///
+/// If the inner closure panics, it will be caught and return an error.
+pub fn with_native_environment<F, U>(ext: &mut Externalities, f: F) -> Result<U>
+	where F: ::std::panic::UnwindSafe + FnOnce() -> U
+{
+	::runtime_io::with_externalities(ext, move || safe_call(f))
+}
 
 /// Delegate for dispatching a CodeExecutor call to native code.
 pub trait NativeExecutionDispatch {
@@ -28,7 +40,7 @@ pub trait NativeExecutionDispatch {
 
 	/// Dispatch a method and input data to be executed natively. Returns `Some` result or `None`
 	/// if the `method` is unknown. Panics if there's an unrecoverable error.
-	fn dispatch(method: &str, data: &[u8]) -> Option<Vec<u8>>;
+	fn dispatch(ext: &mut Externalities, method: &str, data: &[u8]) -> Result<Vec<u8>>;
 }
 
 /// A generic `CodeExecutor` implementation that uses a delegate to determine wasm code equivalence
@@ -38,10 +50,6 @@ pub struct NativeExecutor<D: NativeExecutionDispatch + Sync + Send> {
 	pub _dummy: ::std::marker::PhantomData<D>,
 }
 
-fn safe_call<F: ::std::panic::UnwindSafe + FnOnce() -> Option<Vec<u8>>>(f: F) -> Result<Option<Vec<u8>>> {
-	catch_unwind(f).map_err(|_| ErrorKind::Runtime.into())
-}
-
 impl<D: NativeExecutionDispatch + Sync + Send> CodeExecutor for NativeExecutor<D> {
 	type Error = Error;
 
@@ -53,8 +61,8 @@ impl<D: NativeExecutionDispatch + Sync + Send> CodeExecutor for NativeExecutor<D
 		data: &[u8],
 	) -> Result<Vec<u8>> {
 		if code == D::native_equivalent() {
-			runtime_io::with_externalities(ext, || safe_call(|| D::dispatch(method, data)))?
-				.ok_or(ErrorKind::MethodNotFound(method.to_owned()).into())
+			// call native
+			D::dispatch(ext, method, data)
 		} else {
 			// call into wasm.
 			WasmExecutor.call(ext, code, method, data)

substrate/substrate/primitives/src/block.rs

@@ -19,7 +19,7 @@
 #[cfg(feature = "std")]
 use bytes;
 use rstd::vec::Vec;
-use codec::Slicable;
+use codec::{Input, Slicable};
 use hash::H256;
 
 /// Used to refer to a block number.
@@ -37,8 +37,8 @@ pub type TransactionHash = H256;
 pub struct Transaction(#[cfg_attr(feature = "std", serde(with="bytes"))] pub Vec<u8>);
 
 impl Slicable for Transaction {
-	fn from_slice(value: &mut &[u8]) -> Option<Self> {
-		Vec::<u8>::from_slice(value).map(Transaction)
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
+		Vec::<u8>::decode(input).map(Transaction)
 	}
 
 	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
@@ -54,8 +54,8 @@ impl ::codec::NonTrivialSlicable for Transaction { }
 pub struct Log(#[cfg_attr(feature = "std", serde(with="bytes"))] pub Vec<u8>);
 
 impl Slicable for Log {
-	fn from_slice(value: &mut &[u8]) -> Option<Self> {
-		Vec::<u8>::from_slice(value).map(Log)
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
+		Vec::<u8>::decode(input).map(Log)
 	}
 
 	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
@@ -74,8 +74,8 @@ pub struct Digest {
 }
 
 impl Slicable for Digest {
-	fn from_slice(value: &mut &[u8]) -> Option<Self> {
-		Vec::<Log>::from_slice(value).map(|logs| Digest { logs })
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
+		Vec::<Log>::decode(input).map(|logs| Digest { logs })
 	}
 
 	fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
@@ -97,10 +97,10 @@ pub struct Block {
 }
 
 impl Slicable for Block {
-	fn from_slice(value: &mut &[u8]) -> Option<Self> {
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(Block {
-			header: try_opt!(Slicable::from_slice(value)),
-			transactions: try_opt!(Slicable::from_slice(value)),
+			header: try_opt!(Slicable::decode(input)),
+			transactions: try_opt!(Slicable::decode(input)),
 		})
 	}
 
@@ -152,13 +152,13 @@ impl Header {
 }
 
 impl Slicable for Header {
-	fn from_slice(value: &mut &[u8]) -> Option<Self> {
+	fn decode<I: Input>(input: &mut I) -> Option<Self> {
 		Some(Header {
-			parent_hash: try_opt!(Slicable::from_slice(value)),
-			number: try_opt!(Slicable::from_slice(value)),
-			state_root: try_opt!(Slicable::from_slice(value)),
-			transaction_root: try_opt!(Slicable::from_slice(value)),
-			digest: try_opt!(Slicable::from_slice(value)),
+			parent_hash: try_opt!(Slicable::decode(input)),
+			number: try_opt!(Slicable::decode(input)),
+			state_root: try_opt!(Slicable::decode(input)),
+			transaction_root: try_opt!(Slicable::decode(input)),
+			digest: try_opt!(Slicable::decode(input)),
 		})
 	}
 
@@ -208,6 +208,6 @@ mod tests {
 }"#);
 
 		let v = header.to_vec();
-		assert_eq!(Header::from_slice(&mut &v[..]).unwrap(), header);
+		assert_eq!(Header::decode(&mut &v[..]).unwrap(), header);
 	}
 }

substrate/substrate/primitives/src/hash.rs

@@ -40,8 +40,8 @@ macro_rules! impl_rest {
 		}
 
 		impl ::codec::Slicable for $name {
-			fn from_slice(value: &mut &[u8]) -> Option<Self> {
-				<[u8; $len] as ::codec::Slicable>::from_slice(value).map($name)
+			fn decode<I: ::codec::Input>(input: &mut I) -> Option<Self> {
+				<[u8; $len] as ::codec::Slicable>::decode(input).map($name)
 			}
 
 			fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {

substrate/substrate/runtime-io/with_std.rs

@@ -22,6 +22,8 @@ extern crate substrate_primitives as primitives;
 extern crate triehash;
 extern crate ed25519;
 
+#[doc(hidden)]
+pub extern crate substrate_codec as codec;
 // re-export hashing functions.
 pub use primitives::{blake2_256, twox_128, twox_256};
 
@@ -40,7 +42,7 @@ pub fn storage(key: &[u8]) -> Vec<u8> {
 }
 
 /// Get `key` from storage, placing the value into `value_out` (as much as possible) and return
-/// the number of bytes that the key in storage was.
+/// the number of bytes that the key in storage was beyond the offset.
 pub fn read_storage(key: &[u8], value_out: &mut [u8], value_offset: usize) -> usize {
 	ext::with(|ext| {
 		if let Ok(value) = ext.storage(key) {
@@ -124,11 +126,20 @@ pub fn print<T: Printable + Sized>(value: T) {
 
 #[macro_export]
 macro_rules! impl_stubs {
-	($( $name:ident ),*) => {
-		pub fn dispatch(method: &str, data: &[u8]) -> Option<Vec<u8>> {
+	( $( $name:ident => $invoke:expr ),* ) => {
+		/// Dispatch logic for the native runtime.
+		pub fn dispatch(method: &str, mut data: &[u8]) -> Option<Vec<u8>> {
 			match method {
 				$(
-					stringify!($name) => Some($name(data)),
+					stringify!($name) => {
+						let input = match $crate::codec::Slicable::decode(&mut data) {
+							Some(input) => input,
+							None => panic!("Bad input data provided to {}", stringify!($name)),
+						};
+
+						let output = $invoke(input);
+						Some($crate::codec::Slicable::to_vec(&output))
+					}
 				)*
 				_ => None,
 			}

substrate/substrate/runtime-io/without_std.rs

@@ -17,6 +17,9 @@
 extern crate substrate_runtime_std as rstd;
 extern crate substrate_primitives as primitives;
 
+#[doc(hidden)]
+pub extern crate substrate_codec as codec;
+
 use rstd::intrinsics;
 use rstd::vec::Vec;
 pub use rstd::{mem, slice};
@@ -68,7 +71,7 @@ pub fn set_storage(key: &[u8], value: &[u8]) {
 }
 
 /// Get `key` from storage, placing the value into `value_out` (as much as possible) and return
-/// the number of bytes that the key in storage was.
+/// the number of bytes that the key in storage was beyond the offset.
 pub fn read_storage(key: &[u8], value_out: &mut [u8], value_offset: usize) -> usize {
 	unsafe {
 		ext_get_storage_into(
@@ -178,25 +181,33 @@ pub fn print<T: Printable + Sized>(value: T) {
 
 #[macro_export]
 macro_rules! impl_stubs {
-	( $( $name:ident ),* ) => {
-		pub mod _internal {
-			$(
-				#[no_mangle]
-				pub fn $name(input_data: *mut u8, input_len: usize) -> u64 {
-					let input = if input_len == 0 {
-						&[0u8; 0]
-					} else {
-						unsafe {
-							$crate::slice::from_raw_parts(input_data, input_len)
-						}
-					};
+	( $( $new_name:ident => $invoke:expr ),* ) => {
+		$(
+			#[no_mangle]
+			pub fn $new_name(input_data: *mut u8, input_len: usize) -> u64 {
+				let mut input = if input_len == 0 {
+					&[0u8; 0]
+				} else {
+					unsafe {
+						$crate::slice::from_raw_parts(input_data, input_len)
+					}
+				};
 
-					let output = super::$name(input);
-					let r = output.as_ptr() as u64 + ((output.len() as u64) << 32);
-					$crate::mem::forget(output);
-					r
-				}
-			)*
-		}
+				let input = match $crate::codec::Slicable::decode(&mut input) {
+					Some(input) => input,
+					None => panic!("Bad input data provided to {}", stringify!($name)),
+				};
+
+				let output = ($invoke)(input);
+				let output = $crate::codec::Slicable::to_vec(&output);
+				let res = output.as_ptr() as u64 + ((output.len() as u64) << 32);
+
+				// Leak the output vector to avoid it being freed.
+				// This is fine in a WASM context since the heap
+				// will be discarded after the call.
+				::core::mem::forget(output);
+				res
+			}
+		)*
 	}
 }

substrate/substrate/runtime-std/src/lib.rs

@@ -21,6 +21,7 @@
 #![cfg_attr(not(feature = "std"), feature(lang_items))]
 #![cfg_attr(not(feature = "std"), feature(core_intrinsics))]
 #![cfg_attr(not(feature = "std"), feature(alloc))]
+#![cfg_attr(not(feature = "std"), feature(macro_reexport))]
 
 #![cfg_attr(feature = "std", doc = "Polkadot runtime standard library as compiled when linked with Rust's standard library.")]
 #![cfg_attr(not(feature = "std"), doc = "Polkadot's runtime standard library as compiled without Rust's standard library.")]

substrate/substrate/runtime-std/with_std.rs

@@ -14,12 +14,13 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
-pub use std::vec;
-pub use std::rc;
-pub use std::cell;
 pub use std::boxed;
-pub use std::slice;
+pub use std::cell;
+pub use std::cmp;
+pub use std::iter;
 pub use std::mem;
 pub use std::ops;
-pub use std::iter;
 pub use std::ptr;
+pub use std::rc;
+pub use std::slice;
+pub use std::vec;

substrate/substrate/runtime-std/without_std.rs

@@ -15,19 +15,21 @@
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
 #[cfg(feature = "nightly")]
+#[macro_reexport(vec)]
 extern crate alloc;
 #[cfg(feature = "nightly")]
 extern crate pwasm_libc;
 #[cfg(feature = "nightly")]
 extern crate pwasm_alloc;
 
-pub use alloc::vec;
 pub use alloc::boxed;
 pub use alloc::rc;
-pub use core::mem;
-pub use core::slice;
+pub use alloc::vec;
 pub use core::cell;
-pub use core::ops;
-pub use core::iter;
-pub use core::ptr;
+pub use core::cmp;
 pub use core::intrinsics;
+pub use core::iter;
+pub use core::mem;
+pub use core::ops;
+pub use core::ptr;
+pub use core::slice;