Make some queries private

Convention: we prefix private queries with `_` until salsa support
real visibility.

crates/ra_analysis/src/db.rs

@@ -85,10 +85,10 @@ salsa::database_storage! {
         }
         impl DescriptorDatabase {
             fn module_tree() for ModuleTreeQuery;
-            fn module_descriptor() for SubmodulesQuery;
             fn module_scope() for ModuleScopeQuery;
-            fn fn_syntax() for FnSyntaxQuery;
             fn fn_scopes() for FnScopesQuery;
+            fn _fn_syntax() for FnSyntaxQuery;
+            fn _submodules() for SubmodulesQuery;
         }
     }
 }

crates/ra_analysis/src/descriptors/function/imp.rs

@@ -15,7 +15,7 @@ pub(crate) fn fn_syntax(db: &impl DescriptorDatabase, fn_id: FnId) -> FnDefNode
 }
 
 pub(crate) fn fn_scopes(db: &impl DescriptorDatabase, fn_id: FnId) -> Arc<FnScopes> {
-    let syntax = db.fn_syntax(fn_id);
+    let syntax = db._fn_syntax(fn_id);
     let res = FnScopes::new(syntax.borrowed());
     Arc::new(res)
 }

crates/ra_analysis/src/descriptors/mod.rs

@@ -24,23 +24,24 @@ salsa::query_group! {
             type ModuleTreeQuery;
             use fn module::imp::module_tree;
         }
-        fn submodules(source: ModuleSource) -> Cancelable<Arc<Vec<module::imp::Submodule>>> {
-            type SubmodulesQuery;
-            use fn module::imp::submodules;
-        }
         fn module_scope(source_root_id: SourceRootId, module_id: ModuleId) -> Cancelable<Arc<ModuleScope>> {
             type ModuleScopeQuery;
             use fn module::imp::module_scope;
         }
-        fn fn_syntax(fn_id: FnId) -> FnDefNode {
+        fn fn_scopes(fn_id: FnId) -> Arc<FnScopes> {
+            type FnScopesQuery;
+            use fn function::imp::fn_scopes;
+        }
+
+        fn _fn_syntax(fn_id: FnId) -> FnDefNode {
             type FnSyntaxQuery;
             // Don't retain syntax trees in memory
             storage volatile;
             use fn function::imp::fn_syntax;
         }
-        fn fn_scopes(fn_id: FnId) -> Arc<FnScopes> {
-            type FnScopesQuery;
-            use fn function::imp::fn_scopes;
+        fn _submodules(source: ModuleSource) -> Cancelable<Arc<Vec<module::imp::Submodule>>> {
+            type SubmodulesQuery;
+            use fn module::imp::submodules;
         }
     }
 }

crates/ra_analysis/src/descriptors/module/imp.rs

@@ -155,7 +155,7 @@ fn build_subtree(
         parent,
         children: Vec::new(),
     });
-    for sub in db.submodules(source)?.iter() {
+    for sub in db._submodules(source)?.iter() {
         let link = tree.push_link(LinkData {
             name: sub.name().clone(),
             owner: id,