Queryify `is_doc_hidden`

It came up hot on some profiling of rustdoc I did, so hopefully turning
it into a query will help.

compiler/rustc_middle/src/query/mod.rs

@@ -1035,6 +1035,11 @@
         separate_provide_extern
     }
 
+    /// Determines whether an item is annotated with `doc(hidden)`.
+    query is_doc_hidden(def_id: DefId) -> bool {
+        desc { |tcx| "checking whether `{}` is `doc(hidden)`", tcx.def_path_str(def_id) }
+    }
+
     query item_attrs(def_id: DefId) -> &'tcx [ast::Attribute] {
         desc { |tcx| "collecting attributes of `{}`", tcx.def_path_str(def_id) }
         separate_provide_extern

compiler/rustc_middle/src/ty/mod.rs

@@ -41,7 +41,7 @@
 use rustc_query_system::ich::StableHashingContext;
 use rustc_session::cstore::CrateStoreDyn;
 use rustc_span::symbol::{kw, Ident, Symbol};
-use rustc_span::{sym, Span};
+use rustc_span::Span;
 use rustc_target::abi::Align;
 
 use std::hash::Hash;
@@ -2125,14 +2125,6 @@ pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
         self.sess.contains_name(&self.get_attrs(did), attr)
     }
 
-    /// Determines whether an item is annotated with `doc(hidden)`.
-    pub fn is_doc_hidden(self, did: DefId) -> bool {
-        self.get_attrs(did)
-            .iter()
-            .filter_map(|attr| if attr.has_name(sym::doc) { attr.meta_item_list() } else { None })
-            .any(|items| items.iter().any(|item| item.has_name(sym::hidden)))
-    }
-
     /// Returns `true` if this is an `auto trait`.
     pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
         self.trait_def(trait_def_id).has_auto_impl

compiler/rustc_middle/src/ty/util.rs

@@ -21,7 +21,7 @@
 use rustc_hir::def_id::DefId;
 use rustc_macros::HashStable;
 use rustc_query_system::ich::NodeIdHashingMode;
-use rustc_span::DUMMY_SP;
+use rustc_span::{sym, DUMMY_SP};
 use rustc_target::abi::{Integer, Size, TargetDataLayout};
 use smallvec::SmallVec;
 use std::{fmt, iter};
@@ -1154,6 +1154,14 @@ pub fn normalize_opaque_types<'tcx>(
     val.fold_with(&mut visitor)
 }
 
+/// Determines whether an item is annotated with `doc(hidden)`.
+pub fn is_doc_hidden(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
+    tcx.get_attrs(def_id)
+        .iter()
+        .filter_map(|attr| if attr.has_name(sym::doc) { attr.meta_item_list() } else { None })
+        .any(|items| items.iter().any(|item| item.has_name(sym::hidden)))
+}
+
 pub fn provide(providers: &mut ty::query::Providers) {
-    *providers = ty::query::Providers { normalize_opaque_types, ..*providers }
+    *providers = ty::query::Providers { normalize_opaque_types, is_doc_hidden, ..*providers }
 }