traits: Sprinkle another Sync

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/src/gamestate.rs b/src/gamestate.rs
index 24d61865c5960809dfc2c3f692c8bc67c5a724f3..237e1d6f757fe00bb94ac7e66170976eb47131f2 100644 (file)
--- a/src/gamestate.rs
+++ b/src/gamestate.rs
@@ -99,7 +99,7 @@ impl_downcast!(PieceXData);
 
 #[enum_dispatch]
 #[dyn_upcast]
-pub trait OutlineTrait: Debug + Send + 'static {
+pub trait OutlineTrait: Debug + Sync + Send + 'static {
   fn outline_path(&self, scale: f64) -> Result<Html, IE>;
   fn surround_path(&self) -> Result<Html, IE> {
     self.outline_path(SELECT_SCALE)