Update visibility of intermediate use items.

src/libcore/iter/adapters/mod.rs

@@ -11,6 +11,7 @@ mod flatten;
 mod zip;
 
 pub use self::chain::Chain;
+#[stable(feature = "rust1", since = "1.0.0")]
 pub use self::flatten::{FlatMap, Flatten};
 pub use self::zip::Zip;
 pub(crate) use self::zip::TrustedRandomAccess;

src/libcore/iter/traits/mod.rs

@@ -5,9 +5,11 @@ mod collect;
 mod accum;
 mod marker;
 
+#[stable(feature = "rust1", since = "1.0.0")]
 pub use self::iterator::Iterator;
 pub use self::double_ended::DoubleEndedIterator;
 pub use self::exact_size::ExactSizeIterator;
 pub use self::collect::{FromIterator, IntoIterator, Extend};
 pub use self::accum::{Sum, Product};
+#[stable(feature = "rust1", since = "1.0.0")]
 pub use self::marker::{FusedIterator, TrustedLen};

src/librustc/hir/def.rs

@@ -252,12 +252,14 @@ impl NonMacroAttrKind {
 }
 
 impl Def {
+    /// Return the `DefId` of this `Def` if it has an id, else panic.
     pub fn def_id(&self) -> DefId {
         self.opt_def_id().unwrap_or_else(|| {
             bug!("attempted .def_id() on invalid def: {:?}", self)
         })
     }
 
+    /// Return `Some(..)` with the `DefId` of this `Def` if it has a id, else `None`.
     pub fn opt_def_id(&self) -> Option<DefId> {
         match *self {
             Def::Fn(id) | Def::Mod(id) | Def::Static(id, _) |
@@ -284,6 +286,14 @@ impl Def {
         }
     }
 
+    /// Return the `DefId` of this `Def` if it represents a module.
+    pub fn mod_def_id(&self) -> Option<DefId> {
+        match *self {
+            Def::Mod(id) => Some(id),
+            _ => None,
+        }
+    }
+
     /// A human readable name for the def kind ("function", "module", etc.).
     pub fn kind_name(&self) -> &'static str {
         match *self {

src/librustc/middle/privacy.rs

@@ -11,16 +11,16 @@ use syntax::ast::NodeId;
 // Accessibility levels, sorted in ascending order
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub enum AccessLevel {
-    // Superset of Reachable used to mark impl Trait items.
+    /// Superset of `AccessLevel::Reachable` used to mark impl Trait items.
     ReachableFromImplTrait,
-    // Exported items + items participating in various kinds of public interfaces,
-    // but not directly nameable. For example, if function `fn f() -> T {...}` is
-    // public, then type `T` is reachable. Its values can be obtained by other crates
-    // even if the type itself is not nameable.
+    /// Exported items + items participating in various kinds of public interfaces,
+    /// but not directly nameable. For example, if function `fn f() -> T {...}` is
+    /// public, then type `T` is reachable. Its values can be obtained by other crates
+    /// even if the type itself is not nameable.
     Reachable,
-    // Public items + items accessible to other crates with help of `pub use` re-exports
+    /// Public items + items accessible to other crates with help of `pub use` re-exports
     Exported,
-    // Items accessible to other crates directly, without help of re-exports
+    /// Items accessible to other crates directly, without help of re-exports
     Public,
 }
 
@@ -31,12 +31,17 @@ pub struct AccessLevels<Id = NodeId> {
 }
 
 impl<Id: Hash + Eq> AccessLevels<Id> {
+    /// See `AccessLevel::Reachable`.
     pub fn is_reachable(&self, id: Id) -> bool {
         self.map.get(&id) >= Some(&AccessLevel::Reachable)
     }
+
+    /// See `AccessLevel::Exported`.
     pub fn is_exported(&self, id: Id) -> bool {
         self.map.get(&id) >= Some(&AccessLevel::Exported)
     }
+
+    /// See `AccessLevel::Public`.
     pub fn is_public(&self, id: Id) -> bool {
         self.map.get(&id) >= Some(&AccessLevel::Public)
     }

src/librustc_privacy/lib.rs

@@ -437,6 +437,43 @@ impl<'a, 'tcx> EmbargoVisitor<'a, 'tcx> {
             ev: self,
         }
     }
+
+
+    /// Given the path segments of a `ItemKind::Use`, then we need
+    /// to update the visibility of the intermediate use so that it isn't linted
+    /// by `unreachable_pub`.
+    ///
+    /// This isn't trivial as `path.def` has the `DefId` of the eventual target
+    /// of the use statement not of the next intermediate use statement.
+    ///
+    /// To do this, consider the last two segments of the path to our intermediate
+    /// use statement. We expect the penultimate segment to be a module and the
+    /// last segment to be the name of the item we are exporting. We can then
+    /// look at the items contained in the module for the use statement with that
+    /// name and update that item's visibility.
+    ///
+    /// FIXME: This solution won't work with glob imports and doesn't respect
+    /// namespaces. See <https://github.com/rust-lang/rust/pull/57922#discussion_r251234202>.
+    fn update_visibility_of_intermediate_use_statements(&mut self, segments: &[hir::PathSegment]) {
+        if let Some([module, segment]) = segments.rchunks_exact(2).next() {
+            if let Some(item) = module.def
+                .and_then(|def| def.mod_def_id())
+                .and_then(|def_id| self.tcx.hir().as_local_node_id(def_id))
+                .map(|module_node_id| self.tcx.hir().expect_item(module_node_id))
+             {
+                if let hir::ItemKind::Mod(m) = &item.node {
+                    for item_id in m.item_ids.as_ref() {
+                        let item = self.tcx.hir().expect_item(item_id.id);
+                        let def_id = self.tcx.hir().local_def_id(item_id.id);
+                        if !self.tcx.hygienic_eq(segment.ident, item.ident, def_id) { continue; }
+                        if let hir::ItemKind::Use(..) = item.node {
+                            self.update(item.id, Some(AccessLevel::Exported));
+                        }
+                    }
+                }
+            }
+        }
+    }
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for EmbargoVisitor<'a, 'tcx> {
@@ -523,8 +560,14 @@ impl<'a, 'tcx> Visitor<'tcx> for EmbargoVisitor<'a, 'tcx> {
             hir::ItemKind::ExternCrate(..) => {}
             // All nested items are checked by `visit_item`.
             hir::ItemKind::Mod(..) => {}
-            // Re-exports are handled in `visit_mod`.
-            hir::ItemKind::Use(..) => {}
+            // Re-exports are handled in `visit_mod`. However, in order to avoid looping over
+            // all of the items of a mod in `visit_mod` looking for use statements, we handle
+            // making sure that intermediate use statements have their visibilities updated here.
+            hir::ItemKind::Use(ref path, _) => {
+                if item_level.is_some() {
+                    self.update_visibility_of_intermediate_use_statements(path.segments.as_ref());
+                }
+            }
             // The interface is empty.
             hir::ItemKind::GlobalAsm(..) => {}
             hir::ItemKind::Existential(..) => {

src/libstd/sys/mod.rs

@@ -54,6 +54,7 @@ cfg_if! {
 cfg_if! {
     if #[cfg(any(unix, target_os = "redox"))] {
         // On unix we'll document what's already available
+        #[stable(feature = "rust1", since = "1.0.0")]
         pub use self::ext as unix_ext;
     } else if #[cfg(any(target_os = "cloudabi",
                         target_arch = "wasm32",
@@ -77,6 +78,7 @@ cfg_if! {
     if #[cfg(windows)] {
         // On windows we'll just be documenting what's already available
         #[allow(missing_docs)]
+        #[stable(feature = "rust1", since = "1.0.0")]
         pub use self::ext as windows_ext;
     } else if #[cfg(any(target_os = "cloudabi",
                         target_arch = "wasm32",

src/test/ui/issues/issue-57410-1.rs

@@ -0,0 +1,18 @@
+// compile-pass
+
+// Originally from #53925.
+// Tests that the `unreachable_pub` lint doesn't fire for `pub self::bar::Bar`.
+
+#![deny(unreachable_pub)]
+
+mod foo {
+    mod bar {
+        pub struct Bar;
+    }
+
+    pub use self::bar::Bar;
+}
+
+pub use foo::Bar;
+
+fn main() {}

src/test/ui/issues/issue-57410.rs

@@ -0,0 +1,17 @@
+// compile-pass
+
+// Tests that the `unreachable_pub` lint doesn't fire for `pub self::imp::f`.
+
+#![deny(unreachable_pub)]
+
+mod m {
+    mod imp {
+        pub fn f() {}
+    }
+
+    pub use self::imp::f;
+}
+
+pub use self::m::f;
+
+fn main() {}