Add Rust std::shared_ptr binding
diff --git a/syntax/mod.rs b/syntax/mod.rs
index e8bd290..12b269e 100644
--- a/syntax/mod.rs
+++ b/syntax/mod.rs
@@ -167,6 +167,7 @@
     RustBox(Box<Ty1>),
     RustVec(Box<Ty1>),
     UniquePtr(Box<Ty1>),
+    SharedPtr(Box<Ty1>),
     Ref(Box<Ref>),
     Str(Box<Ref>),
     CxxVector(Box<Ty1>),