Only record the same impl once

Due to inlining it is possible to visit the same module multiple times
during `<Cache as DocFolder>::fold_crate`, so we keep track of the
modules we've already visited.

src/etc/htmldocck.py

@@ -342,9 +342,9 @@ def check_tree_text(tree, path, pat, regexp):
     return ret
 
 
-def check_tree_count(tree, path, count):
+def get_tree_count(tree, path):
     path = normalize_xpath(path)
-    return len(tree.findall(path)) == count
+    return len(tree.findall(path))
 
 def stderr(*args):
     print(*args, file=sys.stderr)
@@ -393,7 +393,10 @@ def check_command(c, cache):
 
         elif c.cmd == 'count': # count test
             if len(c.args) == 3: # @count <path> <pat> <count> = count test
-                ret = check_tree_count(cache.get_tree(c.args[0]), c.args[1], int(c.args[2]))
+                expected = int(c.args[2])
+                found = get_tree_count(cache.get_tree(c.args[0]), c.args[1])
+                cerr = "Expected {} occurrences but found {}".format(expected, found)
+                ret = expected == found
             else:
                 raise InvalidCheck('Invalid number of @{} arguments'.format(c.cmd))
         elif c.cmd == 'valid-html':

src/librustdoc/html/render.rs

@@ -258,6 +258,8 @@ pub struct Cache {
     parent_stack: Vec<DefId>,
     parent_is_trait_impl: bool,
     search_index: Vec<IndexItem>,
+    seen_modules: HashSet<DefId>,
+    seen_mod: bool,
     stripped_mod: bool,
     deref_trait_did: Option<DefId>,
 
@@ -520,6 +522,8 @@ pub fn run(mut krate: clean::Crate,
         parent_is_trait_impl: false,
         extern_locations: HashMap::new(),
         primitive_locations: HashMap::new(),
+        seen_modules: HashSet::new(),
+        seen_mod: false,
         stripped_mod: false,
         access_levels: krate.access_levels.clone(),
         orphan_methods: Vec::new(),
@@ -976,13 +980,20 @@ impl DocFolder for Cache {
         // we don't want it or its children in the search index.
         let orig_stripped_mod = match item.inner {
             clean::StrippedItem(box clean::ModuleItem(..)) => {
-                let prev = self.stripped_mod;
-                self.stripped_mod = true;
-                prev
+                mem::replace(&mut self.stripped_mod, true)
             }
             _ => self.stripped_mod,
         };
 
+        // Inlining can cause us to visit the same item multiple times.
+        // (i.e. relevant for gathering impls and implementors)
+        let orig_seen_mod = if item.is_mod() {
+            let seen_this = self.seen_mod || !self.seen_modules.insert(item.def_id);
+            mem::replace(&mut self.seen_mod, seen_this)
+        } else {
+            self.seen_mod
+        };
+
         // Register any generics to their corresponding string. This is used
         // when pretty-printing types
         match item.inner {
@@ -998,6 +1009,7 @@ impl DocFolder for Cache {
             _ => {}
         }
 
+        if !self.seen_mod {
             // Propagate a trait methods' documentation to all implementors of the
             // trait
             if let clean::TraitItem(ref t) = item.inner {
@@ -1014,6 +1026,7 @@ impl DocFolder for Cache {
                     });
                 }
             }
+        }
 
         // Index this method for searching later on
         if let Some(ref s) = item.name {
@@ -1183,7 +1196,6 @@ impl DocFolder for Cache {
                     } => {
                         Some(did)
                     }
-
                     ref t => {
                         t.primitive_type().and_then(|t| {
                             self.primitive_locations.get(&t).map(|n| {
@@ -1193,7 +1205,7 @@ impl DocFolder for Cache {
                         })
                     }
                 };
-
+                if !self.seen_mod {
                     if let Some(did) = did {
                         self.impls.entry(did).or_insert(vec![]).push(Impl {
                             impl_: i,
@@ -1201,6 +1213,7 @@ impl DocFolder for Cache {
                             stability: item.stability.clone(),
                         });
                     }
+                }
                 None
             } else {
                 Some(item)
@@ -1209,6 +1222,7 @@ impl DocFolder for Cache {
 
         if pushed { self.stack.pop().unwrap(); }
         if parent_pushed { self.parent_stack.pop().unwrap(); }
+        self.seen_mod = orig_seen_mod;
         self.stripped_mod = orig_stripped_mod;
         self.parent_is_trait_impl = orig_parent_is_trait_impl;
         return ret;

src/test/rustdoc/duplicate_impls/impls.rs

@@ -0,0 +1,22 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub struct Foo;
+
+// just so that `Foo` doesn't show up on `Bar`s sidebar
+pub mod bar {
+    pub trait Bar {}
+}
+
+impl Foo {
+    pub fn new() -> Foo { Foo }
+}
+
+impl bar::Bar for Foo {}

src/test/rustdoc/duplicate_impls/issue-33054.rs

@@ -0,0 +1,21 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// @has issue_33054/impls/struct.Foo.html
+// @has - '//code' 'impl Foo'
+// @has - '//code' 'impl Bar for Foo'
+// @count - '//*[@class="impl"]' 2
+// @has issue_33054/impls/bar/trait.Bar.html
+// @has - '//code' 'impl Bar for Foo'
+// @count - '//*[@class="struct"]' 1
+pub mod impls;
+
+#[doc(inline)]
+pub use impls as impls2;