Review nits and updates

Move future_from_generator out of raw
Update await to use $crate
Renumber errors

src/librustc/diagnostics.rs

@@ -2134,7 +2134,7 @@ register_diagnostics! {
 
     E0906, // closures cannot be static
 
-    E0703, // multiple different lifetimes used in arguments of `async fn`
-    E0704, // multiple elided lifetimes used in arguments of `async fn`
-    E0705, // `async` non-`move` closures with arguments are not currently supported
+    E0725, // multiple different lifetimes used in arguments of `async fn`
+    E0726, // multiple elided lifetimes used in arguments of `async fn`
+    E0727, // `async` non-`move` closures with arguments are not currently supported
 }

src/librustc/hir/lowering.rs

@@ -877,7 +877,7 @@ impl<'a> LoweringContext<'a> {
 
         let unstable_span = self.allow_internal_unstable(CompilerDesugaringKind::Async, span);
         let gen_future = self.expr_std_path(
-            unstable_span, &["raw", "future_from_generator"], None, ThinVec::new());
+            unstable_span, &["future", "future_from_generator"], None, ThinVec::new());
         hir::ExprCall(P(gen_future), hir_vec![generator])
     }
 
@@ -2049,7 +2049,7 @@ impl<'a> LoweringContext<'a> {
                             struct_span_err!(
                                 self.context.sess,
                                 current_lt_span.between(lifetime.span),
-                                E0703,
+                                E0725,
                                 "multiple different lifetimes used in arguments of `async fn`",
                             )
                                 .span_label(current_lt_span, "first lifetime here")
@@ -2061,7 +2061,7 @@ impl<'a> LoweringContext<'a> {
                             struct_span_err!(
                                 self.context.sess,
                                 current_lt_span.between(lifetime.span),
-                                E0704,
+                                E0726,
                                 "multiple elided lifetimes used in arguments of `async fn`",
                             )
                                 .span_label(current_lt_span, "first lifetime here")
@@ -2582,9 +2582,10 @@ impl<'a> LoweringContext<'a> {
                 let fn_def_id = self.resolver.definitions().local_def_id(id);
 
                 self.with_new_scopes(|this| {
-                    // Note: we can use non-async decl here because lower_body
-                    // only cares about the input argument patterns,
-                    // not the return types.
+                    // Note: we don't need to change the return type from `T` to
+                    // `impl Future<Output = T>` here because lower_body
+                    // only cares about the input argument patterns in the function
+                    // declaration (decl), not the return types.
                     let body_id = this.lower_body(Some(decl), |this| {
                         if let IsAsync::Async(async_node_id) = header.asyncness {
                             let async_expr = this.make_async_expr(
@@ -3560,7 +3561,7 @@ impl<'a> LoweringContext<'a> {
                             struct_span_err!(
                                 this.sess,
                                 fn_decl_span,
-                                E0705,
+                                E0727,
                                 "`async` non-`move` closures with arguments \
                                 are not currently supported",
                             )

src/libstd/raw.rs → src/libstd/future.rs

@@ -1,4 +1,4 @@
-// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -8,27 +8,18 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![allow(missing_docs)]
-#![unstable(feature = "raw", issue = "27751")]
-
-//! Contains struct definitions for the layout of compiler built-in types.
-//!
-//! They can be used as targets of transmutes in unsafe code for manipulating
-//! the raw representations directly.
-//!
-//! Their definition should always match the ABI defined in `rustc::back::abi`.
+//! Asynchronous values.
 
 use core::cell::Cell;
-use core::future::Future;
 use core::marker::Unpin;
 use core::mem::PinMut;
 use core::option::Option;
 use core::ptr::NonNull;
 use core::task::{self, Poll};
 use core::ops::{Drop, Generator, GeneratorState};
 
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::raw::*;
+#[doc(inline)]
+pub use core::future::*;
 
 /// Wrap a future in a generator.
 ///
@@ -52,7 +43,7 @@ impl<T: Generator<Yield = ()>> !Unpin for GenFuture<T> {}
 impl<T: Generator<Yield = ()>> Future for GenFuture<T> {
     type Output = T::Return;
     fn poll(self: PinMut<Self>, cx: &mut task::Context) -> Poll<Self::Output> {
-        with_set_cx(cx, || match unsafe { PinMut::get_mut(self).0.resume() } {
+        set_task_cx(cx, || match unsafe { PinMut::get_mut(self).0.resume() } {
             GeneratorState::Yielded(()) => Poll::Pending,
             GeneratorState::Complete(x) => Poll::Ready(x),
         })
@@ -74,7 +65,8 @@ impl Drop for SetOnDrop {
 }
 
 #[unstable(feature = "gen_future", issue = "50547")]
-pub fn with_set_cx<F, R>(cx: &mut task::Context, f: F) -> R
+/// Sets the thread-local task context used by async/await futures.
+pub fn set_task_cx<F, R>(cx: &mut task::Context, f: F) -> R
 where
     F: FnOnce() -> R
 {
@@ -90,7 +82,11 @@ where
 }
 
 #[unstable(feature = "gen_future", issue = "50547")]
-pub fn with_get_cx<F, R>(f: F) -> R
+/// Retrieves the thread-local task context used by async/await futures.
+///
+/// Panics if no task has been set or if the task context has already been
+/// retrived by a surrounding call to get_task_cx.
+pub fn get_task_cx<F, R>(f: F) -> R
 where
     F: FnOnce(&mut task::Context) -> R
 {

src/libstd/lib.rs

@@ -411,6 +411,8 @@ pub use core::ops;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::ptr;
 #[stable(feature = "rust1", since = "1.0.0")]
+pub use core::raw;
+#[stable(feature = "rust1", since = "1.0.0")]
 pub use core::result;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::option;
@@ -461,22 +463,6 @@ pub use core::u128;
 #[stable(feature = "core_hint", since = "1.27.0")]
 pub use core::hint;
 
-#[unstable(feature = "futures_api",
-           reason = "futures in libcore are unstable",
-           issue = "50547")]
-pub mod task {
-    //! Types and Traits for working with asynchronous tasks.
-    #[doc(inline)]
-    pub use core::task::*;
-    #[doc(inline)]
-    pub use alloc_crate::task::*;
-}
-
-#[unstable(feature = "futures_api",
-           reason = "futures in libcore are unstable",
-           issue = "50547")]
-pub use core::future;
-
 pub mod f32;
 pub mod f64;
 
@@ -495,10 +481,25 @@ pub mod os;
 pub mod panic;
 pub mod path;
 pub mod process;
-pub mod raw;
 pub mod sync;
 pub mod time;
 
+#[unstable(feature = "futures_api",
+           reason = "futures in libcore are unstable",
+           issue = "50547")]
+pub mod task {
+    //! Types and Traits for working with asynchronous tasks.
+    #[doc(inline)]
+    pub use core::task::*;
+    #[doc(inline)]
+    pub use alloc_crate::task::*;
+}
+
+#[unstable(feature = "futures_api",
+           reason = "futures in libcore are unstable",
+           issue = "50547")]
+pub mod future;
+
 // Platform-abstraction modules
 #[macro_use]
 mod sys_common;

src/libstd/macros.rs

@@ -220,15 +220,15 @@ macro_rules! eprintln {
 macro_rules! await {
     ($e:expr) => { {
         let mut pinned = $e;
-        let mut pinned = unsafe { ::core::mem::PinMut::new_unchecked(&mut pinned) };
+        let mut pinned = unsafe { $crate::mem::PinMut::new_unchecked(&mut pinned) };
         loop {
-            match ::std::raw::with_get_cx(|cx|
-                      ::core::future::Future::poll(pinned.reborrow(), cx))
+            match $crate::future::get_task_cx(|cx|
+                $crate::future::Future::poll(pinned.reborrow(), cx))
             {
                 // FIXME(cramertj) prior to stabilizing await, we have to ensure that this
                 // can't be used to create a generator on stable via `|| await!()`.
-                ::core::task::Poll::Pending => yield,
-                ::core::task::Poll::Ready(x) => break x,
+                $crate::task::Poll::Pending => yield,
+                $crate::task::Poll::Ready(x) => break x,
             }
         }
     } }

src/test/ui/async-fn-multiple-lifetimes.stderr

@@ -1,4 +1,4 @@
-error[E0703]: multiple different lifetimes used in arguments of `async fn`
+error[E0725]: multiple different lifetimes used in arguments of `async fn`
   --> $DIR/async-fn-multiple-lifetimes.rs:17:49
    |
 LL | async fn multiple_named_lifetimes<'a, 'b>(_: &'a u8, _: &'b u8) {}
@@ -8,7 +8,7 @@ LL | async fn multiple_named_lifetimes<'a, 'b>(_: &'a u8, _: &'b u8) {}
    |
    = help: `async fn` can only accept borrowed values with identical lifetimes
 
-error[E0704]: multiple elided lifetimes used in arguments of `async fn`
+error[E0726]: multiple elided lifetimes used in arguments of `async fn`
   --> $DIR/async-fn-multiple-lifetimes.rs:26:39
    |
 LL | async fn multiple_elided_lifetimes(_: &u8, _: &u8) {}
@@ -28,5 +28,5 @@ LL | async fn multiple_elided_lifetimes(_: &u8, _: &u8) {}
 
 error: aborting due to 3 previous errors
 
-Some errors occurred: E0106, E0703, E0704.
+Some errors occurred: E0106, E0725, E0726.
 For more information about an error, try `rustc --explain E0106`.

src/test/ui/no-args-non-move-async-closure.stderr

@@ -1,4 +1,4 @@
-error[E0705]: `async` non-`move` closures with arguments are not currently supported
+error[E0727]: `async` non-`move` closures with arguments are not currently supported
   --> $DIR/no-args-non-move-async-closure.rs:16:13
    |
 LL |     let _ = async |x: u8| {};
@@ -8,4 +8,4 @@ LL |     let _ = async |x: u8| {};
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0705`.
+For more information about this error, try `rustc --explain E0727`.