type checking !?!?

src/ir/upper/def.rs

@@ -1,4 +1,6 @@
-use super::{FileSpan, Type};
+use crate::common::FileSpan;
+
+use super::Type;
 use std::fmt::Debug;
 
 #[derive(Clone)]
@@ -23,6 +25,12 @@ pub struct VarDef {
     pub origin: Origin,
 }
 
+#[derive(Clone)]
+pub struct DataDef {
+    pub ty: Type,
+    pub origin: Origin,
+}
+
 #[derive(Debug, Clone, Copy)]
 pub enum Origin {
     Builtin,