privacy: Mark everything in a header of a reachable impl as reachable

src/librustc_privacy/lib.rs

@@ -552,7 +552,7 @@ impl<'a, 'tcx> Visitor<'tcx> for EmbargoVisitor<'a, 'tcx> {
             // Visit everything except for private impl items.
             hir::ItemKind::Impl(.., ref impl_item_refs) => {
                 if item_level.is_some() {
-                    self.reach(item.id, item_level).generics().predicates();
+                    self.reach(item.id, item_level).generics().predicates().ty().trait_ref();
 
                     for impl_item_ref in impl_item_refs {
                         let impl_item_level = self.get(impl_item_ref.id.node_id);
@@ -711,6 +711,13 @@ impl<'a, 'tcx> ReachEverythingInTheInterfaceVisitor<'_, 'a, 'tcx> {
         self.visit(self.ev.tcx.type_of(self.item_def_id));
         self
     }
+
+    fn trait_ref(&mut self) -> &mut Self {
+        if let Some(trait_ref) = self.ev.tcx.impl_trait_ref(self.item_def_id) {
+            self.visit_trait(trait_ref);
+        }
+        self
+    }
 }
 
 impl<'a, 'tcx> DefIdVisitor<'a, 'tcx> for ReachEverythingInTheInterfaceVisitor<'_, 'a, 'tcx> {

src/test/ui/privacy/auxiliary/issue-57264-2.rs

@@ -0,0 +1,10 @@
+mod inner {
+    pub struct PubUnnameable;
+
+    impl PubUnnameable {
+        pub fn pub_method(self) {}
+    }
+}
+
+pub trait PubTraitWithSingleImplementor {}
+impl PubTraitWithSingleImplementor for Option<inner::PubUnnameable> {}

src/test/ui/privacy/issue-57264-1.rs

@@ -0,0 +1,8 @@
+// compile-pass
+// aux-build:issue-57264-1.rs
+
+extern crate issue_57264_1;
+
+fn main() {
+    issue_57264_1::Pub::pub_method();
+}

src/test/ui/privacy/issue-57264-2.rs

@@ -0,0 +1,10 @@
+// compile-pass
+// aux-build:issue-57264-2.rs
+
+extern crate issue_57264_2;
+
+fn infer<T: issue_57264_2::PubTraitWithSingleImplementor>(arg: T) -> T { arg }
+
+fn main() {
+    infer(None).unwrap().pub_method();
+}