async/await

src/librustc/diagnostics.rs

@@ -2131,5 +2131,10 @@ register_diagnostics! {
     E0657, // `impl Trait` can only capture lifetimes bound at the fn level
     E0687, // in-band lifetimes cannot be used in `fn`/`Fn` syntax
     E0688, // in-band lifetimes cannot be mixed with explicit lifetime binders
-    E0697, // closures cannot be static
+
+    E0906, // closures cannot be static
+
+    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/intravisit.rs

@@ -41,7 +41,6 @@
 //! This order consistency is required in a few places in rustc, for
 //! example generator inference, and possibly also HIR borrowck.
 
-use rustc_target::spec::abi::Abi;
 use syntax::ast::{NodeId, CRATE_NODE_ID, Ident, Name, Attribute};
 use syntax_pos::Span;
 use hir::*;
@@ -54,8 +53,8 @@ use std::u32;
 
 #[derive(Copy, Clone, PartialEq, Eq)]
 pub enum FnKind<'a> {
-    /// fn foo() or extern "Abi" fn foo()
-    ItemFn(Name, &'a Generics, Unsafety, Constness, Abi, &'a Visibility, &'a [Attribute]),
+    /// #[xxx] pub async/const/extern "Abi" fn foo()
+    ItemFn(Name, &'a Generics, FnHeader, &'a Visibility, &'a [Attribute]),
 
     /// fn foo(&self)
     Method(Name, &'a MethodSig, Option<&'a Visibility>, &'a [Attribute]),
@@ -479,12 +478,10 @@ pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item) {
             visitor.visit_ty(typ);
             visitor.visit_nested_body(body);
         }
-        ItemFn(ref declaration, unsafety, constness, abi, ref generics, body_id) => {
+        ItemFn(ref declaration, header, ref generics, body_id) => {
             visitor.visit_fn(FnKind::ItemFn(item.name,
                                             generics,
-                                            unsafety,
-                                            constness,
-                                            abi,
+                                            header,
                                             &item.vis,
                                             &item.attrs),
                              declaration,

src/librustc/hir/map/blocks.rs

@@ -25,7 +25,6 @@ use hir as ast;
 use hir::map::{self, Node};
 use hir::{Expr, FnDecl};
 use hir::intravisit::FnKind;
-use rustc_target::spec::abi;
 use syntax::ast::{Attribute, Name, NodeId};
 use syntax_pos::Span;
 
@@ -105,9 +104,7 @@ impl<'a> Code<'a> {
 struct ItemFnParts<'a> {
     name:     Name,
     decl:     &'a ast::FnDecl,
-    unsafety: ast::Unsafety,
-    constness: ast::Constness,
-    abi:      abi::Abi,
+    header:   ast::FnHeader,
     vis:      &'a ast::Visibility,
     generics: &'a ast::Generics,
     body:     ast::BodyId,
@@ -183,31 +180,31 @@ impl<'a> FnLikeNode<'a> {
 
     pub fn constness(self) -> ast::Constness {
         match self.kind() {
-            FnKind::ItemFn(_, _, _, constness, ..) => {
-                constness
-            }
-            FnKind::Method(_, m, ..) => {
-                m.constness
-            }
+            FnKind::ItemFn(_, _, header, ..) => header.constness,
+            FnKind::Method(_, m, ..) => m.header.constness,
             _ => ast::Constness::NotConst
         }
     }
 
+    pub fn asyncness(self) -> ast::IsAsync {
+        match self.kind() {
+            FnKind::ItemFn(_, _, header, ..) => header.asyncness,
+            FnKind::Method(_, m, ..) => m.header.asyncness,
+            _ => ast::IsAsync::NotAsync
+        }
+    }
+
     pub fn unsafety(self) -> ast::Unsafety {
         match self.kind() {
-            FnKind::ItemFn(_, _, unsafety, ..) => {
-                unsafety
-            }
-            FnKind::Method(_, m, ..) => {
-                m.unsafety
-            }
+            FnKind::ItemFn(_, _, header, ..) => header.unsafety,
+            FnKind::Method(_, m, ..) => m.header.unsafety,
             _ => ast::Unsafety::Normal
         }
     }
 
     pub fn kind(self) -> FnKind<'a> {
         let item = |p: ItemFnParts<'a>| -> FnKind<'a> {
-            FnKind::ItemFn(p.name, p.generics, p.unsafety, p.constness, p.abi, p.vis, p.attrs)
+            FnKind::ItemFn(p.name, p.generics, p.header, p.vis, p.attrs)
         };
         let closure = |c: ClosureParts<'a>| {
             FnKind::Closure(c.attrs)
@@ -232,19 +229,17 @@ impl<'a> FnLikeNode<'a> {
     {
         match self.node {
             map::NodeItem(i) => match i.node {
-                ast::ItemFn(ref decl, unsafety, constness, abi, ref generics, block) =>
+                ast::ItemFn(ref decl, header, ref generics, block) =>
                     item_fn(ItemFnParts {
                         id: i.id,
                         name: i.name,
                         decl: &decl,
-                        unsafety,
                         body: block,
-                        generics,
-                        abi,
                         vis: &i.vis,
-                        constness,
                         span: i.span,
                         attrs: &i.attrs,
+                        header,
+                        generics,
                     }),
                 _ => bug!("item FnLikeNode that is not fn-like"),
             },

src/librustc/hir/map/def_collector.rs

@@ -73,6 +73,27 @@ impl<'a> DefCollector<'a> {
         self.parent_def = parent;
     }
 
+    fn visit_async_fn(
+        &mut self,
+        id: NodeId,
+        async_node_id: NodeId,
+        name: Name,
+        span: Span,
+        visit_fn: impl FnOnce(&mut DefCollector<'a>)
+    ) {
+        // For async functions, we need to create their inner defs inside of a
+        // closure to match their desugared representation.
+        let fn_def_data = DefPathData::ValueNs(name.as_interned_str());
+        let fn_def = self.create_def(id, fn_def_data, ITEM_LIKE_SPACE, span);
+        return self.with_parent(fn_def, |this| {
+            let closure_def = this.create_def(async_node_id,
+                                  DefPathData::ClosureExpr,
+                                  REGULAR_SPACE,
+                                  span);
+            this.with_parent(closure_def, visit_fn)
+        })
+    }
+
     fn visit_macro_invoc(&mut self, id: NodeId) {
         if let Some(ref mut visit) = self.visit_macro_invoc {
             visit(MacroInvocationData {
@@ -99,6 +120,15 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
             ItemKind::Mod(..) if i.ident == keywords::Invalid.ident() => {
                 return visit::walk_item(self, i);
             }
+            ItemKind::Fn(_, FnHeader { asyncness: IsAsync::Async(async_node_id), .. }, ..) => {
+                return self.visit_async_fn(
+                    i.id,
+                    async_node_id,
+                    i.ident.name,
+                    i.span,
+                    |this| visit::walk_item(this, i)
+                )
+            }
             ItemKind::Mod(..) => DefPathData::Module(i.ident.name.as_interned_str()),
             ItemKind::Static(..) | ItemKind::Const(..) | ItemKind::Fn(..) =>
                 DefPathData::ValueNs(i.ident.name.as_interned_str()),
@@ -197,6 +227,17 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
 
     fn visit_impl_item(&mut self, ii: &'a ImplItem) {
         let def_data = match ii.node {
+            ImplItemKind::Method(MethodSig {
+                header: FnHeader { asyncness: IsAsync::Async(async_node_id), .. }, ..
+            }, ..) => {
+                return self.visit_async_fn(
+                    ii.id,
+                    async_node_id,
+                    ii.ident.name,
+                    ii.span,
+                    |this| visit::walk_impl_item(this, ii)
+                )
+            }
             ImplItemKind::Method(..) | ImplItemKind::Const(..) =>
                 DefPathData::ValueNs(ii.ident.name.as_interned_str()),
             ImplItemKind::Type(..) => DefPathData::AssocTypeInImpl(ii.ident.name.as_interned_str()),
@@ -227,15 +268,32 @@ impl<'a> visit::Visitor<'a> for DefCollector<'a> {
 
         match expr.node {
             ExprKind::Mac(..) => return self.visit_macro_invoc(expr.id),
-            ExprKind::Closure(..) => {
-                let def = self.create_def(expr.id,
+            ExprKind::Closure(_, asyncness, ..) => {
+                let closure_def = self.create_def(expr.id,
                                           DefPathData::ClosureExpr,
                                           REGULAR_SPACE,
                                           expr.span);
-                self.parent_def = Some(def);
+                self.parent_def = Some(closure_def);
+
+                // Async closures desugar to closures inside of closures, so
+                // we must create two defs.
+                if let IsAsync::Async(async_id) = asyncness {
+                    let async_def = self.create_def(async_id,
+                                                    DefPathData::ClosureExpr,
+                                                    REGULAR_SPACE,
+                                                    expr.span);
+                    self.parent_def = Some(async_def);
+                }
+            }
+            ExprKind::Async(_, async_id, _) => {
+                let async_def = self.create_def(async_id,
+                                                DefPathData::ClosureExpr,
+                                                REGULAR_SPACE,
+                                                expr.span);
+                self.parent_def = Some(async_def);
             }
             _ => {}
-        }
+        };
 
         visit::walk_expr(self, expr);
         self.parent_def = parent_def;

src/librustc/hir/map/mod.rs

@@ -174,7 +174,7 @@ impl<'hir> MapEntry<'hir> {
         match self {
             EntryItem(_, _, ref item) => {
                 match item.node {
-                    ItemFn(ref fn_decl, _, _, _, _, _) => Some(&fn_decl),
+                    ItemFn(ref fn_decl, _, _, _) => Some(&fn_decl),
                     _ => None,
                 }
             }
@@ -210,7 +210,7 @@ impl<'hir> MapEntry<'hir> {
                 match item.node {
                     ItemConst(_, body) |
                     ItemStatic(.., body) |
-                    ItemFn(_, _, _, _, _, body) => Some(body),
+                    ItemFn(_, _, _, body) => Some(body),
                     _ => None,
                 }
             }

src/librustc/hir/mod.rs

@@ -255,7 +255,7 @@ impl LifetimeName {
         }
     }
 
-    fn is_elided(&self) -> bool {
+    pub fn is_elided(&self) -> bool {
         use self::LifetimeName::*;
         match self {
             Implicit | Underscore => true,
@@ -1506,9 +1506,7 @@ pub struct MutTy {
 /// Represents a method's signature in a trait declaration or implementation.
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub struct MethodSig {
-    pub unsafety: Unsafety,
-    pub constness: Constness,
-    pub abi: Abi,
+    pub header: FnHeader,
     pub decl: P<FnDecl>,
 }
 
@@ -1736,7 +1734,13 @@ pub enum IsAuto {
     No
 }
 
-#[derive(Copy, Clone, PartialEq, Eq,PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug)]
+pub enum IsAsync {
+    Async,
+    NotAsync,
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum Unsafety {
     Unsafe,
     Normal,
@@ -2012,6 +2016,14 @@ pub struct Item {
     pub span: Span,
 }
 
+#[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
+pub struct FnHeader {
+    pub unsafety: Unsafety,
+    pub constness: Constness,
+    pub asyncness: IsAsync,
+    pub abi: Abi,
+}
+
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, Hash, Debug)]
 pub enum Item_ {
     /// An `extern crate` item, with optional *original* crate name if the crate was renamed.
@@ -2031,7 +2043,7 @@ pub enum Item_ {
     /// A `const` item
     ItemConst(P<Ty>, BodyId),
     /// A function declaration
-    ItemFn(P<FnDecl>, Unsafety, Constness, Abi, Generics, BodyId),
+    ItemFn(P<FnDecl>, FnHeader, Generics, BodyId),
     /// A module
     ItemMod(Mod),
     /// An external module
@@ -2096,7 +2108,7 @@ impl Item_ {
 
     pub fn generics(&self) -> Option<&Generics> {
         Some(match *self {
-            ItemFn(_, _, _, _, ref generics, _) |
+            ItemFn(_, _, ref generics, _) |
             ItemTy(_, ref generics) |
             ItemEnum(_, ref generics) |
             ItemStruct(_, ref generics) |