update tracked struct created_at when validated

Fixes #484

components/salsa-2022/src/tracked_struct.rs

@@ -287,11 +287,14 @@ where
 
     fn mark_validated_output(
         &self,
-        _db: &DB,
+        db: &DB,
         _executor: DatabaseKeyIndex,
-        _output_key: Option<crate::Id>,
+        output_key: Option<crate::Id>,
     ) {
-        // FIXME
+        let output_key = output_key.unwrap();
+        let output_key: C::Id = <C::Id>::from_id(output_key);
+        let mut entity = self.entity_data.get_mut(&output_key).unwrap();
+        entity.created_at = db.runtime().current_revision();
     }
 
     fn remove_stale_output(

salsa-2022-tests/tests/tracked-struct-unchanged-in-new-rev.rs

@@ -0,0 +1,47 @@
+use test_log::test;
+
+#[salsa::jar(db = Db)]
+struct Jar(MyInput, MyTracked, tracked_fn);
+
+trait Db: salsa::DbWithJar<Jar> {}
+
+#[salsa::input(jar = Jar)]
+struct MyInput {
+    field: u32,
+}
+
+#[salsa::tracked(jar = Jar)]
+struct MyTracked {
+    field: u32,
+}
+
+#[salsa::tracked(jar = Jar)]
+fn tracked_fn(db: &dyn Db, input: MyInput) -> MyTracked {
+    MyTracked::new(db, input.field(db) / 2)
+}
+
+#[salsa::db(Jar)]
+#[derive(Default)]
+struct Database {
+    storage: salsa::Storage<Self>,
+}
+
+impl salsa::Database for Database {}
+
+impl Db for Database {}
+
+#[test]
+fn execute() {
+    let mut db = Database::default();
+
+    let input1 = MyInput::new(&db, 22);
+    let input2 = MyInput::new(&db, 44);
+    let _tracked1 = tracked_fn(&db, input1);
+    let _tracked2 = tracked_fn(&db, input2);
+
+    // modify the input and change the revision
+    input1.set_field(&mut db).to(24);
+    let tracked2 = tracked_fn(&db, input2);
+
+    tracked2.field(&db);
+}