Shrink ModItem by usize

crates/hir-def/src/item_tree.rs

@@ -51,7 +51,7 @@ use hir_expand::{
     name::Name,
 };
 use intern::Interned;
-use la_arena::Idx;
+use la_arena::{Idx, RawIdx};
 use rustc_hash::FxHashMap;
 use span::{AstIdNode, Edition, FileAstId, SyntaxContext};
 use stdx::never;
@@ -437,10 +437,10 @@ pub struct Use {
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct UseTree {
-    pub index: Idx<ast::UseTree>,
     kind: UseTreeKind,
 }
 
+// FIXME: Would be nice to encode `None` into this
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ImportAlias {
     /// Unnamed alias, as in `use Foo as _;`
@@ -655,15 +655,17 @@ pub enum ImportKind {
     TypeOnly,
 }
 
-impl UseTree {
+impl Use {
     /// Expands the `UseTree` into individually imported `ModPath`s.
     pub fn expand(
         &self,
         mut cb: impl FnMut(Idx<ast::UseTree>, ModPath, ImportKind, Option<ImportAlias>),
     ) {
-        self.expand_impl(None, &mut cb)
+        self.use_tree.expand_impl(None, &mut 0, &mut cb)
     }
+}
 
+impl UseTree {
     /// The [`UseTreeKind`] of this `UseTree`.
     pub fn kind(&self) -> &UseTreeKind {
         &self.kind
@@ -672,6 +674,7 @@ impl UseTree {
     fn expand_impl(
         &self,
         prefix: Option<ModPath>,
+        counting_index: &mut u32,
         cb: &mut impl FnMut(Idx<ast::UseTree>, ModPath, ImportKind, Option<ImportAlias>),
     ) {
         fn concat_mod_paths(
@@ -707,17 +710,27 @@ impl UseTree {
         match &self.kind {
             UseTreeKind::Single { path, alias } => {
                 if let Some((path, kind)) = concat_mod_paths(prefix, path) {
-                    cb(self.index, path, kind, alias.clone());
+                    cb(Idx::from_raw(RawIdx::from_u32(*counting_index)), path, kind, alias.clone());
                 }
             }
             UseTreeKind::Glob { path: Some(path) } => {
                 if let Some((path, _)) = concat_mod_paths(prefix, path) {
-                    cb(self.index, path, ImportKind::Glob, None);
+                    cb(
+                        Idx::from_raw(RawIdx::from_u32(*counting_index)),
+                        path,
+                        ImportKind::Glob,
+                        None,
+                    );
                 }
             }
             UseTreeKind::Glob { path: None } => {
                 if let Some(prefix) = prefix {
-                    cb(self.index, prefix, ImportKind::Glob, None);
+                    cb(
+                        Idx::from_raw(RawIdx::from_u32(*counting_index)),
+                        prefix,
+                        ImportKind::Glob,
+                        None,
+                    );
                 }
             }
             UseTreeKind::Prefixed { prefix: additional_prefix, list } => {
@@ -729,7 +742,8 @@ impl UseTree {
                     None => prefix,
                 };
                 for tree in &**list {
-                    tree.expand_impl(prefix.clone(), cb);
+                    *counting_index += 1;
+                    tree.expand_impl(prefix.clone(), counting_index, cb);
                 }
             }
         }

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

@@ -424,17 +424,15 @@ impl UseTreeLowering<'_> {
                 }
             };
 
+            self.mapping.alloc(tree.clone());
             let list = use_tree_list
                 .use_trees()
                 .filter_map(|tree| self.lower_use_tree(tree, span_for_range))
                 .collect();
 
-            Some(
-                self.use_tree(
-                    UseTreeKind::Prefixed { prefix: prefix.map(Interned::new), list },
-                    tree,
-                ),
-            )
+            Some(UseTree {
+                kind: UseTreeKind::Prefixed { prefix: prefix.map(Interned::new), list },
+            })
         } else {
             let is_glob = tree.star_token().is_some();
             let path = match tree.path() {
@@ -453,23 +451,20 @@ impl UseTreeLowering<'_> {
                     if path.is_none() {
                         cov_mark::hit!(glob_enum_group);
                     }
-                    Some(self.use_tree(UseTreeKind::Glob { path: path.map(Interned::new) }, tree))
+                    self.mapping.alloc(tree.clone());
+                    Some(UseTree { kind: UseTreeKind::Glob { path: path.map(Interned::new) } })
                 }
                 // Globs can't be renamed
                 (_, Some(_), true) | (None, None, false) => None,
                 // `bla::{ as Name}` is invalid
                 (None, Some(_), false) => None,
-                (Some(path), alias, false) => Some(
-                    self.use_tree(UseTreeKind::Single { path: Interned::new(path), alias }, tree),
-                ),
+                (Some(path), alias, false) => {
+                    self.mapping.alloc(tree.clone());
+                    Some(UseTree { kind: UseTreeKind::Single { path: Interned::new(path), alias } })
+                }
             }
         }
     }
-
-    fn use_tree(&mut self, kind: UseTreeKind, ast: ast::UseTree) -> UseTree {
-        let index = self.mapping.alloc(ast);
-        UseTree { index, kind }
-    }
 }
 
 pub(crate) fn lower_use_tree(

crates/hir-def/src/nameres/collector.rs

@@ -163,7 +163,7 @@ impl Import {
     ) {
         let it = &tree[item];
         let visibility = &tree[it.visibility];
-        it.use_tree.expand(|idx, path, kind, alias| {
+        it.expand(|idx, path, kind, alias| {
             cb(Self {
                 path,
                 alias,

crates/intern/src/symbol.rs

@@ -112,6 +112,7 @@ impl TaggedArcPtr {
     }
 }
 
+// FIXME: This should have more than one niche
 #[derive(PartialEq, Eq, Hash)]
 pub struct Symbol {
     repr: TaggedArcPtr,