1 files changed, 64 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/middle/privacy.rs b/compiler/rustc_middle/src/middle/privacy.rs
new file mode 100644
index 000000000..751c7f464
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+++ b/compiler/rustc_middle/src/middle/privacy.rs
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+//! A pass that checks to make sure private fields and methods aren't used
+//! outside their scopes. This pass will also generate a set of exported items
+//! which are available for use externally when compiled as a library.
+
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_macros::HashStable;
+use rustc_query_system::ich::StableHashingContext;
+use rustc_span::def_id::LocalDefId;
+use std::hash::Hash;
+
+/// Represents the levels of accessibility an item can have.
+///
+/// The variants are sorted in ascending order of accessibility.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, HashStable)]
+pub enum AccessLevel {
+    /// 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.
+    Reachable,
+    /// Public items + items accessible to other crates with the help of `pub use` re-exports.
+    Exported,
+    /// Items accessible to other crates directly, without the help of re-exports.
+    Public,
+}
+
+/// Holds a map of accessibility levels for reachable HIR nodes.
+#[derive(Debug, Clone)]
+pub struct AccessLevels<Id = LocalDefId> {
+    pub map: FxHashMap<Id, AccessLevel>,
+}
+
+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)
+    }
+}
+
+impl<Id> Default for AccessLevels<Id> {
+    fn default() -> Self {
+        AccessLevels { map: Default::default() }
+    }
+}
+
+impl<'a> HashStable<StableHashingContext<'a>> for AccessLevels {
+    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
+        let AccessLevels { ref map } = *self;
+        map.hash_stable(hcx, hasher);
+    }
+}