3 files changed, 45 insertions, 31 deletions

diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index 443b057ab..c69e0efea 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -60,13 +60,10 @@ pub(super) fn lower(
     params: Option<ast::ParamList>,
     body: Option<ast::Expr>,
 ) -> (Body, BodySourceMap) {
-    let ctx = LowerCtx::new(db, expander.current_file_id.clone());
-
     ExprCollector {
         db,
         def,
         expander,
-        ctx,
         source_map: BodySourceMap::default(),
         body: Body {
             exprs: Arena::default(),
@@ -83,7 +80,6 @@ struct ExprCollector<'a> {
     db: &'a dyn DefDatabase,
     def: DefWithBodyId,
     expander: Expander,
-    ctx: LowerCtx,
     body: Body,
     source_map: BodySourceMap,
 }
@@ -122,6 +118,10 @@ impl ExprCollector<'_> {
         (self.body, self.source_map)
     }
 
+    fn ctx(&self) -> LowerCtx {
+        LowerCtx::new(self.db, self.expander.current_file_id)
+    }
+
     fn alloc_expr(&mut self, expr: Expr, ptr: AstPtr<ast::Expr>) -> ExprId {
         let src = self.expander.to_source(ptr);
         let id = self.make_expr(expr, Ok(src.clone()));
@@ -268,7 +268,7 @@ impl ExprCollector<'_> {
                 };
                 let method_name = e.name_ref().map(|nr| nr.as_name()).unwrap_or_else(Name::missing);
                 let generic_args =
-                    e.type_arg_list().and_then(|it| GenericArgs::from_ast(&self.ctx, it));
+                    e.type_arg_list().and_then(|it| GenericArgs::from_ast(&self.ctx(), it));
                 self.alloc_expr(
                     Expr::MethodCall { receiver, method_name, args, generic_args },
                     syntax_ptr,
@@ -373,7 +373,7 @@ impl ExprCollector<'_> {
             }
             ast::Expr::CastExpr(e) => {
                 let expr = self.collect_expr_opt(e.expr());
-                let type_ref = TypeRef::from_ast_opt(&self.ctx, e.type_ref());
+                let type_ref = TypeRef::from_ast_opt(&self.ctx(), e.type_ref());
                 self.alloc_expr(Expr::Cast { expr, type_ref }, syntax_ptr)
             }
             ast::Expr::RefExpr(e) => {
@@ -396,7 +396,7 @@ impl ExprCollector<'_> {
                     for param in pl.params() {
                         let pat = self.collect_pat_opt(param.pat());
                         let type_ref =
-                            param.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx, it));
+                            param.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx(), it));
                         args.push(pat);
                         arg_types.push(type_ref);
                     }
@@ -404,7 +404,7 @@ impl ExprCollector<'_> {
                 let ret_type = e
                     .ret_type()
                     .and_then(|r| r.type_ref())
-                    .map(|it| TypeRef::from_ast(&self.ctx, it));
+                    .map(|it| TypeRef::from_ast(&self.ctx(), it));
                 let body = self.collect_expr_opt(e.body());
                 self.alloc_expr(Expr::Lambda { args, arg_types, ret_type, body }, syntax_ptr)
             }
@@ -507,7 +507,8 @@ impl ExprCollector<'_> {
             .map(|s| match s {
                 ast::Stmt::LetStmt(stmt) => {
                     let pat = self.collect_pat_opt(stmt.pat());
-                    let type_ref = stmt.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx, it));
+                    let type_ref =
+                        stmt.ascribed_type().map(|it| TypeRef::from_ast(&self.ctx(), it));
                     let initializer = stmt.initializer().map(|e| self.collect_expr(e));
                     Statement::Let { pat, type_ref, initializer }
                 }
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index e665ab45d..2f71511ba 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -1,7 +1,7 @@
 //! Defines database & queries for name resolution.
 use std::sync::Arc;
 
-use hir_expand::{db::AstDatabase, HirFileId};
+use hir_expand::{db::AstDatabase, name::Name, HirFileId};
 use ra_db::{salsa, CrateId, SourceDatabase, Upcast};
 use ra_prof::profile;
 use ra_syntax::SmolStr;
@@ -12,9 +12,12 @@ use crate::{
     body::{scope::ExprScopes, Body, BodySourceMap},
     data::{ConstData, FunctionData, ImplData, StaticData, TraitData, TypeAliasData},
     docs::Documentation,
+    find_path,
     generics::GenericParams,
+    item_scope::ItemInNs,
     lang_item::{LangItemTarget, LangItems},
     nameres::{raw::RawItems, CrateDefMap},
+    visibility::Visibility,
     AttrDefId, ConstId, ConstLoc, DefWithBodyId, EnumId, EnumLoc, FunctionId, FunctionLoc,
     GenericDefId, ImplId, ImplLoc, ModuleId, StaticId, StaticLoc, StructId, StructLoc, TraitId,
     TraitLoc, TypeAliasId, TypeAliasLoc, UnionId, UnionLoc,
@@ -108,6 +111,13 @@ pub trait DefDatabase: InternDatabase + AstDatabase + Upcast<dyn AstDatabase> {
     // Remove this query completely, in favor of `Attrs::docs` method
     #[salsa::invoke(Documentation::documentation_query)]
     fn documentation(&self, def: AttrDefId) -> Option<Documentation>;
+
+    #[salsa::invoke(find_path::importable_locations_of_query)]
+    fn importable_locations_of(
+        &self,
+        item: ItemInNs,
+        krate: CrateId,
+    ) -> Arc<[(ModuleId, Name, Visibility)]>;
 }
 
 fn crate_def_map_wait(db: &impl DefDatabase, krate: CrateId) -> Arc<CrateDefMap> {
diff --git a/crates/ra_hir_def/src/find_path.rs b/crates/ra_hir_def/src/find_path.rs
index 70dcb03e6..2eb12ec8f 100644
--- a/crates/ra_hir_def/src/find_path.rs
+++ b/crates/ra_hir_def/src/find_path.rs
@@ -1,5 +1,11 @@
 //! An algorithm to find a path to refer to a certain item.
 
+use std::sync::Arc;
+
+use hir_expand::name::{known, AsName, Name};
+use ra_prof::profile;
+use test_utils::tested_by;
+
 use crate::{
     db::DefDatabase,
     item_scope::ItemInNs,
@@ -7,25 +13,28 @@ use crate::{
     visibility::Visibility,
     CrateId, ModuleDefId, ModuleId,
 };
-use hir_expand::name::{known, AsName, Name};
-use test_utils::tested_by;
+
+// FIXME: handle local items
+
+/// Find a path that can be used to refer to a certain item. This can depend on
+/// *from where* you're referring to the item, hence the `from` parameter.
+pub fn find_path(db: &dyn DefDatabase, item: ItemInNs, from: ModuleId) -> Option<ModPath> {
+    let _p = profile("find_path");
+    find_path_inner(db, item, from, MAX_PATH_LEN)
+}
 
 const MAX_PATH_LEN: usize = 15;
 
 impl ModPath {
     fn starts_with_std(&self) -> bool {
-        self.segments.first().filter(|&first_segment| first_segment == &known::std).is_some()
+        self.segments.first() == Some(&known::std)
     }
 
     // When std library is present, paths starting with `std::`
     // should be preferred over paths starting with `core::` and `alloc::`
     fn can_start_with_std(&self) -> bool {
-        self.segments
-            .first()
-            .filter(|&first_segment| {
-                first_segment == &known::alloc || first_segment == &known::core
-            })
-            .is_some()
+        let first_segment = self.segments.first();
+        first_segment == Some(&known::alloc) || first_segment == Some(&known::core)
     }
 
     fn len(&self) -> usize {
@@ -40,14 +49,6 @@ impl ModPath {
     }
 }
 
-// FIXME: handle local items
-
-/// Find a path that can be used to refer to a certain item. This can depend on
-/// *from where* you're referring to the item, hence the `from` parameter.
-pub fn find_path(db: &dyn DefDatabase, item: ItemInNs, from: ModuleId) -> Option<ModPath> {
-    find_path_inner(db, item, from, MAX_PATH_LEN)
-}
-
 fn find_path_inner(
     db: &dyn DefDatabase,
     item: ItemInNs,
@@ -198,7 +199,7 @@ fn find_importable_locations(
         .chain(crate_graph[from.krate].dependencies.iter().map(|dep| dep.crate_id))
     {
         result.extend(
-            importable_locations_in_crate(db, item, krate)
+            db.importable_locations_of(item, krate)
                 .iter()
                 .filter(|(_, _, vis)| vis.is_visible_from(db, from))
                 .map(|(m, n, _)| (*m, n.clone())),
@@ -213,11 +214,12 @@ fn find_importable_locations(
 ///
 /// Note that the crate doesn't need to be the one in which the item is defined;
 /// it might be re-exported in other crates.
-fn importable_locations_in_crate(
+pub(crate) fn importable_locations_of_query(
     db: &dyn DefDatabase,
     item: ItemInNs,
     krate: CrateId,
-) -> Vec<(ModuleId, Name, Visibility)> {
+) -> Arc<[(ModuleId, Name, Visibility)]> {
+    let _p = profile("importable_locations_of_query");
     let def_map = db.crate_def_map(krate);
     let mut result = Vec::new();
     for (local_id, data) in def_map.modules.iter() {
@@ -243,7 +245,8 @@ fn importable_locations_in_crate(
             result.push((ModuleId { krate, local_id }, name.clone(), vis));
         }
     }
-    result
+
+    Arc::from(result)
 }
 
 #[cfg(test)]