Remove some Arcs

Unfortunately, this causes `Semantics` to become invariant over its lifetime, which necessitates large changes, but the changes from `hir` downwards are mechanical and could use a skim review.

Author: ChayimFriedman2

crates/hir-def/src/attrs/docs.rs

@@ -333,7 +333,7 @@ struct DocExprSourceCtx<'db> {
     resolver: Resolver<'db>,
     file_id: HirFileId,
     ast_id_map: &'db AstIdMap,
-    span_map: SpanMap,
+    span_map: SpanMap<'db>,
 }
 
 fn expand_doc_expr_via_macro_pipeline<'db>(
@@ -390,7 +390,7 @@ fn expand_doc_macro_call<'db>(
     .value?;
 
     expander.recursion_depth += 1;
-    let parse = expander.db.parse_macro_expansion(call_id).value.0;
+    let parse = expander.db.parse_macro_expansion(call_id).value.0.clone();
     let expr = parse.cast::<ast::Expr>().map(|parse| parse.tree())?;
     expander.recursion_depth -= 1;
 

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

@@ -5,10 +5,8 @@ use std::mem;
 use base_db::Crate;
 use cfg::CfgOptions;
 use drop_bomb::DropBomb;
-use hir_expand::AstId;
-use hir_expand::span_map::SpanMapRef;
 use hir_expand::{
-    ExpandError, ExpandErrorKind, ExpandResult, HirFileId, InFile, Lookup, MacroCallId,
+    AstId, ExpandError, ExpandErrorKind, ExpandResult, HirFileId, InFile, Lookup, MacroCallId,
     eager::EagerCallBackFn, mod_path::ModPath, span_map::SpanMap,
 };
 use span::{AstIdMap, SyntaxContext};
@@ -23,7 +21,7 @@ use crate::{
 
 #[derive(Debug)]
 pub(super) struct Expander<'db> {
-    span_map: SpanMap,
+    span_map: SpanMap<'db>,
     current_file_id: HirFileId,
     ast_id_map: &'db AstIdMap,
     /// `recursion_depth == usize::MAX` indicates that the recursion limit has been reached.
@@ -58,11 +56,11 @@ impl<'db> Expander<'db> {
     }
 
     pub(super) fn hygiene_for_range(&self, db: &dyn DefDatabase, range: TextRange) -> HygieneId {
-        match self.span_map.as_ref() {
-            hir_expand::span_map::SpanMapRef::ExpansionSpanMap(span_map) => {
+        match self.span_map {
+            SpanMap::ExpansionSpanMap(span_map) => {
                 HygieneId::new(span_map.span_at(range.start()).ctx.opaque_and_semiopaque(db))
             }
-            hir_expand::span_map::SpanMapRef::RealSpanMap(_) => HygieneId::ROOT,
+            SpanMap::RealSpanMap(_) => HygieneId::ROOT,
         }
     }
 
@@ -193,15 +191,15 @@ impl<'db> Expander<'db> {
 
         let res = db.parse_macro_expansion(call_id);
 
-        let err = err.or(res.err);
+        let err = err.or_else(|| res.err.clone());
         ExpandResult {
             value: {
-                let parse = res.value.0.cast::<T>();
+                let parse = res.value.0.clone().cast::<T>();
 
                 self.recursion_depth += 1;
                 let old_file_id = std::mem::replace(&mut self.current_file_id, call_id.into());
                 let old_span_map =
-                    std::mem::replace(&mut self.span_map, db.span_map(self.current_file_id));
+                    std::mem::replace(&mut self.span_map, SpanMap::ExpansionSpanMap(&res.value.1));
                 let prev_ast_id_map =
                     mem::replace(&mut self.ast_id_map, db.ast_id_map(self.current_file_id));
                 let mark = Mark {
@@ -222,15 +220,15 @@ impl<'db> Expander<'db> {
     }
 
     #[inline]
-    pub(super) fn span_map(&self) -> SpanMapRef<'_> {
-        self.span_map.as_ref()
+    pub(super) fn span_map(&self) -> SpanMap<'_> {
+        self.span_map
     }
 }
 
 #[derive(Debug)]
 pub(super) struct Mark<'db> {
     file_id: HirFileId,
-    span_map: SpanMap,
+    span_map: SpanMap<'db>,
     ast_id_map: &'db AstIdMap,
     bomb: DropBomb,
 }

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

@@ -14,7 +14,7 @@ use either::Either;
 use hir_expand::{
     HirFileId, InFile, MacroDefId,
     name::{AsName, Name},
-    span_map::SpanMapRef,
+    span_map::SpanMap,
 };
 use intern::{Symbol, sym};
 use rustc_hash::FxHashMap;
@@ -585,7 +585,7 @@ impl<'db> ExprCollector<'db> {
     }
 
     #[inline]
-    pub(crate) fn span_map(&self) -> SpanMapRef<'_> {
+    pub(crate) fn span_map(&self) -> SpanMap<'_> {
         self.expander.span_map()
     }
 

crates/hir-def/src/find_path.rs

@@ -684,7 +684,7 @@ mod tests {
         let ast_path =
             parsed_path_file.syntax_node().descendants().find_map(syntax::ast::Path::cast).unwrap();
         let mod_path = ModPath::from_src(&db, ast_path, &mut |range| {
-            db.span_map(pos.file_id.into()).as_ref().span_for_range(range).ctx
+            db.span_map(pos.file_id.into()).span_for_range(range).ctx
         })
         .unwrap();
 

crates/hir-def/src/item_tree.rs

@@ -40,7 +40,6 @@ use std::{
     fmt::{self, Debug},
     hash::Hash,
     ops::Index,
-    sync::OnceLock,
 };
 
 use ast::{AstNode, StructKind};
@@ -61,7 +60,6 @@ use span::{
 use stdx::never;
 use syntax::{SourceFile, SyntaxKind, ast, match_ast};
 use thin_vec::ThinVec;
-use triomphe::Arc;
 use tt::TextRange;
 
 use crate::{BlockId, Lookup, attrs::parse_extra_crate_attrs, db::DefDatabase};
@@ -121,14 +119,13 @@ fn lower_extra_crate_attrs<'a>(
     AttrsOrCfg::lower(db, &crate_attrs_as_src, cfg_options, span_map)
 }
 
-#[salsa_macros::tracked(returns(deref))]
+#[salsa_macros::tracked(returns(ref))]
 pub(crate) fn file_item_tree_query(
     db: &dyn DefDatabase,
     file_id: HirFileId,
     krate: Crate,
-) -> Arc<ItemTree> {
+) -> ItemTree {
     let _p = tracing::info_span!("file_item_tree_query", ?file_id).entered();
-    static EMPTY: OnceLock<Arc<ItemTree>> = OnceLock::new();
 
     let ctx = lower::Ctx::new(db, file_id, krate);
     let syntax = db.parse_or_expand(file_id);
@@ -174,21 +171,17 @@ pub(crate) fn file_item_tree_query(
         && top_attrs.is_empty()
         && vis.arena.is_empty()
     {
-        EMPTY
-            .get_or_init(|| {
-                Arc::new(ItemTree {
-                    top_level: Box::new([]),
-                    attrs: FxHashMap::default(),
-                    small_data: FxHashMap::default(),
-                    big_data: FxHashMap::default(),
-                    top_attrs: AttrsOrCfg::empty(),
-                    vis: ItemVisibilities { arena: ThinVec::new() },
-                })
-            })
-            .clone()
+        ItemTree {
+            top_level: Box::new([]),
+            attrs: FxHashMap::default(),
+            small_data: FxHashMap::default(),
+            big_data: FxHashMap::default(),
+            top_attrs: AttrsOrCfg::empty(),
+            vis: ItemVisibilities { arena: ThinVec::new() },
+        }
     } else {
         item_tree.shrink_to_fit();
-        Arc::new(item_tree)
+        item_tree
     }
 }
 

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

@@ -4,12 +4,7 @@ use std::cell::OnceCell;
 
 use base_db::{Crate, FxIndexSet};
 use cfg::CfgOptions;
-use hir_expand::{
-    HirFileId,
-    mod_path::PathKind,
-    name::AsName,
-    span_map::{SpanMap, SpanMapRef},
-};
+use hir_expand::{HirFileId, mod_path::PathKind, name::AsName, span_map::SpanMap};
 use la_arena::Arena;
 use span::{AstIdMap, FileAstId, SyntaxContext};
 use syntax::{
@@ -32,7 +27,7 @@ pub(super) struct Ctx<'db> {
     pub(super) db: &'db dyn DefDatabase,
     tree: ItemTree,
     source_ast_id_map: &'db AstIdMap,
-    span_map: OnceCell<SpanMap>,
+    span_map: OnceCell<SpanMap<'db>>,
     file: HirFileId,
     cfg_options: OnceCell<&'db CfgOptions>,
     krate: Crate,
@@ -60,8 +55,8 @@ impl<'db> Ctx<'db> {
         self.cfg_options.get_or_init(|| self.krate.cfg_options(self.db))
     }
 
-    pub(super) fn span_map(&self) -> SpanMapRef<'_> {
-        self.span_map.get_or_init(|| self.db.span_map(self.file)).as_ref()
+    pub(super) fn span_map(&self) -> SpanMap<'_> {
+        *self.span_map.get_or_init(|| self.db.span_map(self.file))
     }
 
     pub(super) fn lower_module_items(mut self, item_owner: &dyn HasModuleItem) -> ItemTree {

crates/hir-def/src/macro_expansion_tests/mod.rs

@@ -22,7 +22,7 @@ use hir_expand::{
     builtin::quote::quote,
     db::ExpandDatabase,
     proc_macro::{ProcMacro, ProcMacroExpander, ProcMacroExpansionError, ProcMacroKind},
-    span_map::SpanMapRef,
+    span_map::SpanMap,
 };
 use intern::{Symbol, sym};
 use itertools::Itertools;
@@ -142,10 +142,10 @@ pub fn identity_when_valid(_attr: TokenStream, item: TokenStream) -> TokenStream
         }
 
         let mut expn_text = String::new();
-        if let Some(err) = exp.err {
+        if let Some(err) = &exp.err {
             format_to!(expn_text, "/* error: {} */", err.render_to_string(&db).message);
         }
-        let (parse, token_map) = exp.value;
+        let (parse, token_map) = &exp.value;
         if expect_errors {
             assert!(!parse.errors().is_empty(), "no parse errors in expansion");
             for e in parse.errors() {
@@ -161,7 +161,7 @@ pub fn identity_when_valid(_attr: TokenStream, item: TokenStream) -> TokenStream
         }
         let pp = pretty_print_macro_expansion(
             parse.syntax_node(),
-            SpanMapRef::ExpansionSpanMap(&token_map),
+            SpanMap::ExpansionSpanMap(token_map),
             show_spans,
             show_ctxt,
         );
@@ -215,7 +215,7 @@ pub fn identity_when_valid(_attr: TokenStream, item: TokenStream) -> TokenStream
             }
             let pp = pretty_print_macro_expansion(
                 src.value,
-                db.span_map(src.file_id).as_ref(),
+                db.span_map(src.file_id),
                 show_spans,
                 show_ctxt,
             );
@@ -230,7 +230,7 @@ pub fn identity_when_valid(_attr: TokenStream, item: TokenStream) -> TokenStream
         if let Some(macro_file) = src.file_id.macro_file() {
             let pp = pretty_print_macro_expansion(
                 src.value.syntax().clone(),
-                db.span_map(macro_file.into()).as_ref(),
+                db.span_map(macro_file.into()),
                 false,
                 false,
             );
@@ -245,7 +245,7 @@ pub fn identity_when_valid(_attr: TokenStream, item: TokenStream) -> TokenStream
         {
             let pp = pretty_print_macro_expansion(
                 src.value.syntax().clone(),
-                db.span_map(macro_file.into()).as_ref(),
+                db.span_map(macro_file.into()),
                 false,
                 false,
             );
@@ -309,7 +309,7 @@ fn reindent(indent: IndentLevel, pp: String) -> String {
 
 fn pretty_print_macro_expansion(
     expn: SyntaxNode,
-    map: SpanMapRef<'_>,
+    map: SpanMap<'_>,
     show_spans: bool,
     show_ctxt: bool,
 ) -> String {

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

@@ -138,7 +138,7 @@ struct AssocItemCollector<'db> {
     def_map: &'db DefMap,
     local_def_map: &'db LocalDefMap,
     ast_id_map: &'db AstIdMap,
-    span_map: SpanMap,
+    span_map: SpanMap<'db>,
     cfg_options: &'db CfgOptions,
     file_id: HirFileId,
     diagnostics: Vec<DefDiagnostic>,
@@ -191,19 +191,18 @@ impl<'db> AssocItemCollector<'db> {
 
     fn collect_item(&mut self, item: ast::AssocItem) {
         let ast_id = self.ast_id_map.ast_id(&item);
-        let attrs =
-            match AttrsOrCfg::lower(self.db, &item, &|| self.cfg_options, self.span_map.as_ref()) {
-                AttrsOrCfg::Enabled { attrs } => attrs,
-                AttrsOrCfg::CfgDisabled(cfg) => {
-                    self.diagnostics.push(DefDiagnostic::unconfigured_code(
-                        self.module_id,
-                        InFile::new(self.file_id, ast_id.erase()),
-                        cfg.0,
-                        self.cfg_options.clone(),
-                    ));
-                    return;
-                }
-            };
+        let attrs = match AttrsOrCfg::lower(self.db, &item, &|| self.cfg_options, self.span_map) {
+            AttrsOrCfg::Enabled { attrs } => attrs,
+            AttrsOrCfg::CfgDisabled(cfg) => {
+                self.diagnostics.push(DefDiagnostic::unconfigured_code(
+                    self.module_id,
+                    InFile::new(self.file_id, ast_id.erase()),
+                    cfg.0,
+                    self.cfg_options.clone(),
+                ));
+                return;
+            }
+        };
         let ast_id = InFile::new(self.file_id, ast_id.upcast());
 
         'attrs: for (attr_id, attr) in attrs.as_ref().iter() {
@@ -357,7 +356,7 @@ impl<'db> AssocItemCollector<'db> {
             return;
         }
 
-        let (syntax, span_map) = self.db.parse_macro_expansion(macro_call_id).value;
+        let (syntax, span_map) = &self.db.parse_macro_expansion(macro_call_id).value;
         let old_file_id = mem::replace(&mut self.file_id, macro_call_id.into());
         let old_ast_id_map = mem::replace(&mut self.ast_id_map, self.db.ast_id_map(self.file_id));
         let old_span_map = mem::replace(&mut self.span_map, SpanMap::ExpansionSpanMap(span_map));