Rustdoc render async function re-export

src/librustc/query/mod.rs

@@ -244,6 +244,10 @@ rustc_queries! {
             desc { |tcx| "checking if item is const fn: `{}`", tcx.def_path_str(key) }
         }
 
+        query asyncness(key: DefId) -> hir::IsAsync {
+            desc { |tcx| "checking if the function is async: `{}`", tcx.def_path_str(key) }
+        }
+
         /// Returns `true` if calls to the function may be promoted.
         ///
         /// This is either because the function is e.g., a tuple-struct or tuple-variant

src/librustc/ty/mod.rs

@@ -3349,13 +3349,30 @@ fn issue33140_self_ty(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Ty<'_>> {
     }
 }
 
+/// Check if a function is async.
+fn asyncness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::IsAsync {
+    let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap_or_else(|| {
+        bug!("asyncness: expected local `DefId`, got `{:?}`", def_id)
+    });
+
+    let node = tcx.hir().get(hir_id);
+
+    let fn_like = hir::map::blocks::FnLikeNode::from_node(node).unwrap_or_else(|| {
+        bug!("asyncness: expected fn-like node but got `{:?}`", def_id);
+    });
+
+    fn_like.asyncness()
+}
+
+
 pub fn provide(providers: &mut ty::query::Providers<'_>) {
     context::provide(providers);
     erase_regions::provide(providers);
     layout::provide(providers);
     util::provide(providers);
     constness::provide(providers);
     *providers = ty::query::Providers {
+        asyncness,
         associated_item,
         associated_item_def_ids,
         adt_sized_constraint,

src/librustc_metadata/cstore_impl.rs

@@ -133,6 +133,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     fn_sig => { cdata.fn_sig(def_id.index, tcx) }
     inherent_impls => { cdata.get_inherent_implementations_for_type(tcx, def_id.index) }
     is_const_fn_raw => { cdata.is_const_fn_raw(def_id.index) }
+    asyncness => { cdata.asyncness(def_id.index) }
     is_foreign_item => { cdata.is_foreign_item(def_id.index) }
     static_mutability => { cdata.static_mutability(def_id.index) }
     def_kind => { cdata.def_kind(def_id.index) }

src/librustc_metadata/decoder.rs

@@ -1208,6 +1208,15 @@ impl<'a, 'tcx> CrateMetadata {
         constness == hir::Constness::Const
     }
 
+    pub fn asyncness(&self, id: DefIndex) -> hir::IsAsync {
+         match self.entry(id).kind {
+            EntryKind::Fn(data) => data.decode(self).asyncness,
+            EntryKind::Method(data) => data.decode(self).fn_data.asyncness,
+            EntryKind::ForeignFn(data) => data.decode(self).asyncness,
+            _ => bug!("asyncness: expect functions entry."),
+        }
+    }
+
     pub fn is_foreign_item(&self, id: DefIndex) -> bool {
         match self.entry(id).kind {
             EntryKind::ForeignImmStatic |

src/librustc_metadata/encoder.rs

@@ -875,7 +875,7 @@ impl EncodeContext<'tcx> {
                 EntryKind::AssocConst(container, const_qualif, rendered_const)
             }
             ty::AssocKind::Method => {
-                let fn_data = if let hir::TraitItemKind::Method(_, ref m) = ast_item.node {
+                let fn_data = if let hir::TraitItemKind::Method(method_sig, m) = &ast_item.node {
                     let param_names = match *m {
                         hir::TraitMethod::Required(ref names) => {
                             self.encode_fn_param_names(names)
@@ -885,6 +885,7 @@ impl EncodeContext<'tcx> {
                         }
                     };
                     FnData {
+                        asyncness: method_sig.header.asyncness,
                         constness: hir::Constness::NotConst,
                         param_names,
                         sig: self.lazy(&tcx.fn_sig(def_id)),
@@ -982,6 +983,7 @@ impl EncodeContext<'tcx> {
             ty::AssocKind::Method => {
                 let fn_data = if let hir::ImplItemKind::Method(ref sig, body) = ast_item.node {
                     FnData {
+                        asyncness: sig.header.asyncness,
                         constness: sig.header.constness,
                         param_names: self.encode_fn_param_names_for_body(body),
                         sig: self.lazy(&tcx.fn_sig(def_id)),
@@ -1128,6 +1130,7 @@ impl EncodeContext<'tcx> {
             }
             hir::ItemKind::Fn(_, header, .., body) => {
                 let data = FnData {
+                    asyncness: header.asyncness,
                     constness: header.constness,
                     param_names: self.encode_fn_param_names_for_body(body),
                     sig: self.lazy(tcx.fn_sig(def_id)),
@@ -1675,6 +1678,7 @@ impl EncodeContext<'tcx> {
         let kind = match nitem.node {
             hir::ForeignItemKind::Fn(_, ref names, _) => {
                 let data = FnData {
+                    asyncness: hir::IsAsync::NotAsync,
                     constness: hir::Constness::NotConst,
                     param_names: self.encode_fn_param_names(names),
                     sig: self.lazy(tcx.fn_sig(def_id)),

src/librustc_metadata/schema.rs

@@ -295,6 +295,7 @@ pub struct MacroDef {
 
 #[derive(RustcEncodable, RustcDecodable)]
 pub struct FnData<'tcx> {
+    pub asyncness: hir::IsAsync,
     pub constness: hir::Constness,
     pub param_names: Lazy<[ast::Name]>,
     pub sig: Lazy<ty::PolyFnSig<'tcx>>,

src/librustdoc/clean/inline.rs

@@ -217,7 +217,7 @@ fn build_external_function(cx: &DocContext<'_>, did: DefId) -> clean::Function {
     } else {
         hir::Constness::NotConst
     };
-
+    let asyncness =  cx.tcx.asyncness(did);
     let predicates = cx.tcx.predicates_of(did);
     let (generics, decl) = clean::enter_impl_trait(cx, || {
         ((cx.tcx.generics_of(did), &predicates).clean(cx), (did, sig).clean(cx))
@@ -230,7 +230,7 @@ fn build_external_function(cx: &DocContext<'_>, did: DefId) -> clean::Function {
             unsafety: sig.unsafety(),
             abi: sig.abi(),
             constness,
-            asyncness: hir::IsAsync::NotAsync,
+            asyncness,
         },
         all_types,
         ret_types,

src/librustdoc/clean/mod.rs

@@ -2403,6 +2403,7 @@ impl Clean<Item> for ty::AssocItem {
                     } else {
                         hir::Constness::NotConst
                     };
+                    let asyncness = cx.tcx.asyncness(self.def_id);
                     let defaultness = match self.container {
                         ty::ImplContainer(_) => Some(self.defaultness),
                         ty::TraitContainer(_) => None,
@@ -2414,7 +2415,7 @@ impl Clean<Item> for ty::AssocItem {
                             unsafety: sig.unsafety(),
                             abi: sig.abi(),
                             constness,
-                            asyncness: hir::IsAsync::NotAsync,
+                            asyncness,
                         },
                         defaultness,
                         all_types,

src/test/rustdoc/inline_cross/auxiliary/impl_trait_aux.rs

@@ -1,3 +1,5 @@
+// edition:2018
+
 use std::ops::Deref;
 
 pub fn func<'a>(_x: impl Clone + Into<Vec<u8>> + 'a) {}
@@ -11,8 +13,16 @@ pub fn func3(_x: impl Iterator<Item = impl Iterator<Item = u8>> + Clone) {}
 
 pub fn func4<T: Iterator<Item = impl Clone>>(_x: T) {}
 
+pub async fn async_fn() {}
+
 pub struct Foo;
 
 impl Foo {
     pub fn method<'a>(_x: impl Clone + Into<Vec<u8>> + 'a) {}
 }
+
+pub struct Bar;
+
+impl Bar {
+    pub async fn async_foo(&self) {}
+}

src/test/rustdoc/inline_cross/impl_trait.rs

@@ -1,4 +1,5 @@
 // aux-build:impl_trait_aux.rs
+// edition:2018
 
 extern crate impl_trait_aux;
 
@@ -20,13 +21,20 @@ pub use impl_trait_aux::func2;
 // @!has - '//pre[@class="rust fn"]' 'where'
 pub use impl_trait_aux::func3;
 
-
 // @has impl_trait/fn.func4.html
 // @has - '//pre[@class="rust fn"]' "func4<T>("
 // @has - '//pre[@class="rust fn"]' "T: Iterator<Item = impl Clone>,"
 pub use impl_trait_aux::func4;
 
+// @has impl_trait/fn.async_fn.html
+// @has - '//pre[@class="rust fn"]' "pub async fn async_fn()"
+pub use impl_trait_aux::async_fn;
+
 // @has impl_trait/struct.Foo.html
 // @has - '//code[@id="method.v"]' "pub fn method<'a>(_x: impl Clone + Into<Vec<u8>> + 'a)"
 // @!has - '//code[@id="method.v"]' 'where'
 pub use impl_trait_aux::Foo;
+
+// @has impl_trait/struct.Bar.html
+// @has - '//*[@id="method.async_foo"]' "pub async fn async_foo("
+pub use impl_trait_aux::Bar;