ItemTree's ItemVisibilities has no identity, so deduplicate

crates/hir-def/src/expr_store/lower.rs

@@ -7,6 +7,7 @@ mod path;
 
 use std::mem;
 
+use base_db::FxIndexSet;
 use cfg::CfgOptions;
 use either::Either;
 use hir_expand::{
@@ -66,8 +67,6 @@ use crate::{
 
 pub use self::path::hir_segment_to_ast_segment;
 
-type FxIndexSet<K> = indexmap::IndexSet<K, std::hash::BuildHasherDefault<rustc_hash::FxHasher>>;
-
 pub(super) fn lower_body(
     db: &dyn DefDatabase,
     owner: DefWithBodyId,

crates/hir-def/src/item_tree.rs

@@ -246,7 +246,7 @@ impl ItemTree {
                 macro_calls,
                 macro_rules,
                 macro_defs,
-                vis,
+                vis: _,
             } = &mut **data;
 
             uses.shrink_to_fit();
@@ -266,36 +266,13 @@ impl ItemTree {
             macro_calls.shrink_to_fit();
             macro_rules.shrink_to_fit();
             macro_defs.shrink_to_fit();
-
-            vis.arena.shrink_to_fit();
         }
     }
 }
 
 #[derive(Default, Debug, Eq, PartialEq)]
 struct ItemVisibilities {
-    arena: Arena<RawVisibility>,
-}
-
-impl ItemVisibilities {
-    fn alloc(&mut self, vis: RawVisibility) -> RawVisibilityId {
-        match &vis {
-            RawVisibility::Public => RawVisibilityId::PUB,
-            RawVisibility::Module(path, explicitiy) if path.segments().is_empty() => {
-                match (path.kind, explicitiy) {
-                    (PathKind::SELF, VisibilityExplicitness::Explicit) => {
-                        RawVisibilityId::PRIV_EXPLICIT
-                    }
-                    (PathKind::SELF, VisibilityExplicitness::Implicit) => {
-                        RawVisibilityId::PRIV_IMPLICIT
-                    }
-                    (PathKind::Crate, _) => RawVisibilityId::PUB_CRATE,
-                    _ => RawVisibilityId(self.arena.alloc(vis).into_raw().into()),
-                }
-            }
-            _ => RawVisibilityId(self.arena.alloc(vis).into_raw().into()),
-        }
-    }
+    arena: Box<[RawVisibility]>,
 }
 
 #[derive(Default, Debug, Eq, PartialEq)]
@@ -577,7 +554,7 @@ impl Index<RawVisibilityId> for ItemTree {
                     VisibilityExplicitness::Explicit,
                 )
             }),
-            _ => &self.data().vis.arena[Idx::from_raw(index.0.into())],
+            _ => &self.data().vis.arena[index.0 as usize],
         }
     }
 }
@@ -702,7 +679,7 @@ pub enum FieldsShape {
 }
 
 /// Visibility of an item, not yet resolved.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum RawVisibility {
     /// `pub(in module)`, `pub(crate)` or `pub(super)`. Also private, which is
     /// equivalent to `pub(self)`.

crates/hir-def/src/item_tree/lower.rs

@@ -2,6 +2,7 @@
 
 use std::{cell::OnceCell, collections::hash_map::Entry};
 
+use base_db::FxIndexSet;
 use hir_expand::{
     HirFileId,
     mod_path::PathKind,
@@ -37,6 +38,7 @@ pub(super) struct Ctx<'a> {
     source_ast_id_map: Arc<AstIdMap>,
     span_map: OnceCell<SpanMap>,
     file: HirFileId,
+    visibilities: FxIndexSet<RawVisibility>,
 }
 
 impl<'a> Ctx<'a> {
@@ -47,6 +49,7 @@ impl<'a> Ctx<'a> {
             source_ast_id_map: db.ast_id_map(file),
             file,
             span_map: OnceCell::new(),
+            visibilities: FxIndexSet::default(),
         }
     }
 
@@ -57,6 +60,9 @@ impl<'a> Ctx<'a> {
     pub(super) fn lower_module_items(mut self, item_owner: &dyn HasModuleItem) -> ItemTree {
         self.tree.top_level =
             item_owner.items().flat_map(|item| self.lower_mod_item(&item)).collect();
+        if let Some(data) = &mut self.tree.data {
+            data.vis.arena = self.visibilities.into_iter().collect();
+        }
         self.tree
     }
 
@@ -90,6 +96,9 @@ impl<'a> Ctx<'a> {
             }
         }
 
+        if let Some(data) = &mut self.tree.data {
+            data.vis.arena = self.visibilities.into_iter().collect();
+        }
         self.tree
     }
 
@@ -115,7 +124,9 @@ impl<'a> Ctx<'a> {
                 }
             }
         }
-
+        if let Some(data) = &mut self.tree.data {
+            data.vis.arena = self.visibilities.into_iter().collect();
+        }
         self.tree
     }
 
@@ -370,7 +381,22 @@ impl<'a> Ctx<'a> {
         let vis = visibility_from_ast(self.db, item.visibility(), &mut |range| {
             self.span_map().span_for_range(range).ctx
         });
-        self.data().vis.alloc(vis)
+        match &vis {
+            RawVisibility::Public => RawVisibilityId::PUB,
+            RawVisibility::Module(path, explicitiy) if path.segments().is_empty() => {
+                match (path.kind, explicitiy) {
+                    (PathKind::SELF, VisibilityExplicitness::Explicit) => {
+                        RawVisibilityId::PRIV_EXPLICIT
+                    }
+                    (PathKind::SELF, VisibilityExplicitness::Implicit) => {
+                        RawVisibilityId::PRIV_IMPLICIT
+                    }
+                    (PathKind::Crate, _) => RawVisibilityId::PUB_CRATE,
+                    _ => RawVisibilityId(self.visibilities.insert_full(vis).0 as u32),
+                }
+            }
+            _ => RawVisibilityId(self.visibilities.insert_full(vis).0 as u32),
+        }
     }
 }