Calculate visibilities once in resolve

Then use them through a query based on resolver outputs

compiler/rustc_middle/src/middle/stability.rs

@@ -256,24 +256,12 @@ pub enum EvalResult {
 }
 
 // See issue #38412.
-fn skip_stability_check_due_to_privacy(tcx: TyCtxt<'_>, mut def_id: DefId) -> bool {
-    // Check if `def_id` is a trait method.
-    match tcx.def_kind(def_id) {
-        DefKind::AssocFn | DefKind::AssocTy | DefKind::AssocConst => {
-            if let ty::TraitContainer(trait_def_id) = tcx.associated_item(def_id).container {
-                // Trait methods do not declare visibility (even
-                // for visibility info in cstore). Use containing
-                // trait instead, so methods of `pub` traits are
-                // themselves considered `pub`.
-                def_id = trait_def_id;
-            }
-        }
-        _ => {}
+fn skip_stability_check_due_to_privacy(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
+    if tcx.def_kind(def_id) == DefKind::TyParam {
+        // Have no visibility, considered public for the purpose of this check.
+        return false;
     }
-
-    let visibility = tcx.visibility(def_id);
-
-    match visibility {
+    match tcx.visibility(def_id) {
         // Must check stability for `pub` items.
         ty::Visibility::Public => false,
 

compiler/rustc_middle/src/query/mod.rs

@@ -1267,6 +1267,7 @@ rustc_queries! {
 
     TypeChecking {
         query visibility(def_id: DefId) -> ty::Visibility {
+            eval_always
             desc { |tcx| "computing visibility of `{}`", tcx.def_path_str(def_id) }
         }
     }

compiler/rustc_middle/src/ty/context.rs

@@ -22,7 +22,7 @@ use crate::ty::{
     ExistentialPredicate, FloatVar, FloatVid, GenericParamDefKind, InferConst, InferTy, IntVar,
     IntVid, List, ParamConst, ParamTy, PolyFnSig, Predicate, PredicateInner, PredicateKind,
     ProjectionTy, Region, RegionKind, ReprOptions, TraitObjectVisitor, Ty, TyKind, TyS, TyVar,
-    TyVid, TypeAndMut,
+    TyVid, TypeAndMut, Visibility,
 };
 use rustc_ast as ast;
 use rustc_ast::expand::allocator::AllocatorKind;
@@ -911,6 +911,9 @@ pub struct GlobalCtxt<'tcx> {
     /// Common consts, pre-interned for your convenience.
     pub consts: CommonConsts<'tcx>,
 
+    /// Visibilities produced by resolver.
+    pub visibilities: FxHashMap<LocalDefId, Visibility>,
+
     /// Resolutions of `extern crate` items produced by resolver.
     extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
 
@@ -1124,6 +1127,7 @@ impl<'tcx> TyCtxt<'tcx> {
             types: common_types,
             lifetimes: common_lifetimes,
             consts: common_consts,
+            visibilities: resolutions.visibilities,
             extern_crate_map: resolutions.extern_crate_map,
             trait_map,
             export_map: resolutions.export_map,

compiler/rustc_middle/src/ty/mod.rs

@@ -125,6 +125,7 @@ mod sty;
 pub struct ResolverOutputs {
     pub definitions: rustc_hir::definitions::Definitions,
     pub cstore: Box<CrateStoreDyn>,
+    pub visibilities: FxHashMap<LocalDefId, Visibility>,
     pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
     pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
     pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,