Add default keyword handling in rustdoc

src/librustdoc/clean/mod.rs

@@ -507,6 +507,18 @@ impl Item {
             .as_ref()
             .or_else(|| self.stability.as_ref().and_then(|s| s.deprecation.as_ref()))
     }
+    pub fn is_default(&self) -> bool {
+        match self.inner {
+            ItemEnum::MethodItem(ref meth) => {
+                if let Some(defaultness) = meth.defaultness {
+                    defaultness.has_value() && !defaultness.is_final()
+                } else {
+                    false
+                }
+            }
+            _ => false,
+        }
+    }
 }
 
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug)]
@@ -1699,9 +1711,11 @@ pub struct Method {
     pub generics: Generics,
     pub decl: FnDecl,
     pub header: hir::FnHeader,
+    pub defaultness: Option<hir::Defaultness>,
 }
 
-impl<'a> Clean<Method> for (&'a hir::MethodSig, &'a hir::Generics, hir::BodyId) {
+impl<'a> Clean<Method> for (&'a hir::MethodSig, &'a hir::Generics, hir::BodyId,
+                            Option<hir::Defaultness>) {
     fn clean(&self, cx: &DocContext<'_>) -> Method {
         let (generics, decl) = enter_impl_trait(cx, || {
             (self.1.clean(cx), (&*self.0.decl, self.2).clean(cx))
@@ -1710,6 +1724,7 @@ impl<'a> Clean<Method> for (&'a hir::MethodSig, &'a hir::Generics, hir::BodyId)
             decl,
             generics,
             header: self.0.header,
+            defaultness: self.3,
         }
     }
 }
@@ -2015,7 +2030,7 @@ impl Clean<Item> for hir::TraitItem {
                                     default.map(|e| print_const_expr(cx, e)))
             }
             hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Provided(body)) => {
-                MethodItem((sig, &self.generics, body).clean(cx))
+                MethodItem((sig, &self.generics, body, None).clean(cx))
             }
             hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Required(ref names)) => {
                 let (generics, decl) = enter_impl_trait(cx, || {
@@ -2053,7 +2068,7 @@ impl Clean<Item> for hir::ImplItem {
                                     Some(print_const_expr(cx, expr)))
             }
             hir::ImplItemKind::Method(ref sig, body) => {
-                MethodItem((sig, &self.generics, body).clean(cx))
+                MethodItem((sig, &self.generics, body, Some(self.defaultness)).clean(cx))
             }
             hir::ImplItemKind::Type(ref ty) => TypedefItem(Typedef {
                 type_: ty.clean(cx),
@@ -2136,7 +2151,8 @@ impl<'tcx> Clean<Item> for ty::AssociatedItem {
                             abi: sig.abi(),
                             constness,
                             asyncness: hir::IsAsync::NotAsync,
-                        }
+                        },
+                        defaultness: Some(self.defaultness),
                     })
                 } else {
                     TyMethodItem(TyMethod {

src/librustdoc/html/format.rs

@@ -45,6 +45,7 @@ pub struct GenericBounds<'a>(pub &'a [clean::GenericBound]);
 /// Wrapper struct for emitting a comma-separated list of items
 pub struct CommaSep<'a, T>(pub &'a [T]);
 pub struct AbiSpace(pub Abi);
+pub struct DefaultSpace(pub bool);
 
 /// Wrapper struct for properly emitting a function or method declaration.
 pub struct Function<'a> {
@@ -1057,3 +1058,13 @@ impl fmt::Display for AbiSpace {
         }
     }
 }
+
+impl fmt::Display for DefaultSpace {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.0 {
+            write!(f, "default ")
+        } else {
+            Ok(())
+        }
+    }
+}

src/librustdoc/html/render.rs

@@ -61,7 +61,7 @@ use crate::doctree;
 use crate::fold::DocFolder;
 use crate::html::escape::Escape;
 use crate::html::format::{AsyncSpace, ConstnessSpace};
-use crate::html::format::{GenericBounds, WhereClause, href, AbiSpace};
+use crate::html::format::{GenericBounds, WhereClause, href, AbiSpace, DefaultSpace};
 use crate::html::format::{VisSpace, Function, UnsafetySpace, MutableSpace};
 use crate::html::format::fmt_impl_for_trait_page;
 use crate::html::item_type::ItemType;
@@ -3434,11 +3434,12 @@ fn render_assoc_item(w: &mut fmt::Formatter<'_>,
             }
         };
         let mut header_len = format!(
-            "{}{}{}{}{:#}fn {}{:#}",
+            "{}{}{}{}{}{:#}fn {}{:#}",
             VisSpace(&meth.visibility),
             ConstnessSpace(header.constness),
             UnsafetySpace(header.unsafety),
             AsyncSpace(header.asyncness),
+            DefaultSpace(meth.is_default()),
             AbiSpace(header.abi),
             name,
             *g
@@ -3450,12 +3451,13 @@ fn render_assoc_item(w: &mut fmt::Formatter<'_>,
             (0, true)
         };
         render_attributes(w, meth)?;
-        write!(w, "{}{}{}{}{}fn <a href='{href}' class='fnname'>{name}</a>\
+        write!(w, "{}{}{}{}{}{}fn <a href='{href}' class='fnname'>{name}</a>\
                    {generics}{decl}{where_clause}",
                VisSpace(&meth.visibility),
                ConstnessSpace(header.constness),
                UnsafetySpace(header.unsafety),
                AsyncSpace(header.asyncness),
+               DefaultSpace(meth.is_default()),
                AbiSpace(header.abi),
                href = href,
                name = name,

src/test/rustdoc/default_trait_method.rs

@@ -0,0 +1,15 @@
+#![feature(specialization)]
+
+pub trait Item {
+    fn foo();
+    fn bar();
+}
+
+// @has default_trait_method/trait.Item.html
+// @has - '//*[@id="method.foo"]' 'default fn foo()'
+// @has - '//*[@id="method.bar"]' 'fn bar()'
+// @!has - '//*[@id="method.bar"]' 'default fn bar()'
+impl<T: ?Sized> Item for T {
+    default fn foo() {}
+    fn bar() {}
+}