Auto merge of #29822 - petrochenkov:pubexport, r=alexcrichton

This patch implements the plan described in https://internals.rust-lang.org/t/privacy-and-its-interaction-with-docs-lints-and-stability/2880 with one deviation.

It turns out, that rustdoc needs the "directly public" set for its docs inlining logic, so the privacy pass have to produce three sets and not two. Three is arguably too many, so I merged them in one map:
`public_items/exported_items/reachable_items: NodeSet => access_levels: NodeMap<AccessLevel>`

r? @alexcrichton

src/librustdoc/html/render.rs

@@ -56,8 +56,8 @@ use serialize::json::{self, ToJson};
 use syntax::{abi, ast};
 use rustc::metadata::cstore::LOCAL_CRATE;
 use rustc::middle::def_id::{CRATE_DEF_INDEX, DefId};
+use rustc::middle::privacy::AccessLevels;
 use rustc::middle::stability;
-use rustc::util::nodemap::DefIdSet;
 use rustc_front::hir;
 
 use clean::{self, SelfTy};
@@ -244,7 +244,7 @@ pub struct Cache {
     search_index: Vec<IndexItem>,
     privmod: bool,
     remove_priv: bool,
-    public_items: DefIdSet,
+    access_levels: AccessLevels<DefId>,
     deref_trait_did: Option<DefId>,
 
     // In rare case where a structure is defined in one module but implemented
@@ -415,8 +415,8 @@ pub fn run(mut krate: clean::Crate,
     // Crawl the crate to build various caches used for the output
     let analysis = ::ANALYSISKEY.with(|a| a.clone());
     let analysis = analysis.borrow();
-    let public_items = analysis.as_ref().map(|a| a.public_items.clone());
-    let public_items = public_items.unwrap_or(DefIdSet());
+    let access_levels = analysis.as_ref().map(|a| a.access_levels.clone());
+    let access_levels = access_levels.unwrap_or(Default::default());
     let paths: HashMap<DefId, (Vec<String>, ItemType)> =
       analysis.as_ref().map(|a| {
         let paths = a.external_paths.borrow_mut().take().unwrap();
@@ -435,7 +435,7 @@ pub fn run(mut krate: clean::Crate,
         primitive_locations: HashMap::new(),
         remove_priv: cx.passes.contains("strip-private"),
         privmod: false,
-        public_items: public_items,
+        access_levels: access_levels,
         orphan_methods: Vec::new(),
         traits: mem::replace(&mut krate.external_traits, HashMap::new()),
         deref_trait_did: analysis.as_ref().and_then(|a| a.deref_trait_did),
@@ -1053,7 +1053,7 @@ impl DocFolder for Cache {
                 if
                     !self.paths.contains_key(&item.def_id) ||
                     !item.def_id.is_local() ||
-                    self.public_items.contains(&item.def_id)
+                    self.access_levels.is_public(item.def_id)
                 {
                     self.paths.insert(item.def_id,
                                       (self.stack.clone(), shortty(&item)));