rustdoc: Run external traits through filters

This ensures that all external traits are run through the same filters that the
rest of the AST goes through, stripping hidden function as necessary.

Closes #13698

src/librustdoc/html/render.rs

@@ -44,6 +44,7 @@ use std::fs::{self, File};
 use std::io::prelude::*;
 use std::io::{self, BufWriter, BufReader};
 use std::iter::repeat;
+use std::mem;
 use std::path::{PathBuf, Path};
 use std::str;
 use std::sync::Arc;
@@ -383,9 +384,7 @@ pub fn run(mut krate: clean::Crate,
         privmod: false,
         public_items: public_items,
         orphan_methods: Vec::new(),
-        traits: analysis.as_ref().map(|a| {
-            a.external_traits.borrow_mut().take().unwrap()
-        }).unwrap_or(HashMap::new()),
+        traits: mem::replace(&mut krate.external_traits, HashMap::new()),
         typarams: analysis.as_ref().map(|a| {
             a.external_typarams.borrow_mut().take().unwrap()
         }).unwrap_or(HashMap::new()),
@@ -2239,7 +2238,7 @@ fn render_impl(w: &mut fmt::Formatter, i: &Impl) -> fmt::Result {
     }
 
     try!(write!(w, "<div class='impl-items'>"));
-    for trait_item in &i.impl_.items {
+    for trait_item in i.impl_.items.iter() {
         try!(doctraititem(w, trait_item, true));
     }
 
@@ -2262,17 +2261,10 @@ fn render_impl(w: &mut fmt::Formatter, i: &Impl) -> fmt::Result {
     // default methods which weren't overridden in the implementation block.
     // FIXME: this also needs to be done for associated types, whenever defaults
     // for them work.
-    match i.impl_.trait_ {
-        Some(clean::ResolvedPath { did, .. }) => {
-            try!({
-                match cache().traits.get(&did) {
-                    Some(t) => try!(render_default_methods(w, t, &i.impl_)),
-                    None => {}
-                }
-                Ok(())
-            })
+    if let Some(clean::ResolvedPath { did, .. }) = i.impl_.trait_ {
+        if let Some(t) = cache().traits.get(&did) {
+            try!(render_default_methods(w, t, &i.impl_));
         }
-        Some(..) | None => {}
     }
     try!(write!(w, "</div>"));
     Ok(())