add gc request

crates/ra_ide_api/src/imp.rs

@@ -72,13 +72,14 @@ impl db::RootDatabase {
         self.set_source_root(root_id, Arc::new(source_root));
     }
 
-    #[allow(unused)]
     /// Ideally, we should call this function from time to time to collect heavy
     /// syntax trees. However, if we actually do that, everything is recomputed
     /// for some reason. Needs investigation.
-    fn gc_syntax_trees(&mut self) {
+    pub(crate) fn collect_garbage(&mut self) {
         self.query(ra_db::SourceFileQuery)
             .sweep(salsa::SweepStrategy::default().discard_values());
+        self.query(hir::db::HirSourceFileQuery)
+            .sweep(salsa::SweepStrategy::default().discard_values());
         self.query(hir::db::FileItemsQuery)
             .sweep(salsa::SweepStrategy::default().discard_values());
         self.query(hir::db::FileItemQuery)

crates/ra_ide_api/src/lib.rs

@@ -285,6 +285,10 @@ impl AnalysisHost {
     pub fn apply_change(&mut self, change: AnalysisChange) {
         self.db.apply_change(change)
     }
+
+    pub fn collect_garbage(&mut self) {
+        self.db.collect_garbage();
+    }
 }
 
 /// Analysis is a snapshot of a world state at a moment in time. It is the main