fix: compile error when using enum in flutter

libs/flutter_rust_bridge_codegen/src/ir/ty_boxed.rs

@@ -0,0 +1,56 @@
+use crate::ir::IrType::Primitive;
+use crate::ir::*;
+
+#[derive(Debug, Clone)]
+pub struct IrTypeBoxed {
+    /// if false, means that we automatically add it when transforming it - it does not exist in real api.
+    pub exist_in_real_api: bool,
+    pub inner: Box<IrType>,
+}
+
+impl IrTypeTrait for IrTypeBoxed {
+    fn visit_children_types<F: FnMut(&IrType) -> bool>(&self, f: &mut F, ir_file: &IrFile) {
+        self.inner.visit_types(f, ir_file);
+    }
+
+    fn safe_ident(&self) -> String {
+        format!(
+            "box_{}{}",
+            if self.exist_in_real_api {
+                ""
+            } else {
+                "autoadd_"
+            },
+            self.inner.safe_ident()
+        )
+    }
+
+    fn dart_api_type(&self) -> String {
+        self.inner.dart_api_type()
+    }
+
+    fn dart_wire_type(&self) -> String {
+        let wire_type = if let Primitive(prim) = &*self.inner {
+            prim.dart_native_type().to_owned()
+        } else {
+            self.inner.dart_wire_type()
+        };
+        format!("ffi.Pointer<{}>", wire_type)
+    }
+
+    fn rust_api_type(&self) -> String {
+        if self.exist_in_real_api {
+            format!("Box<{}>", self.inner.rust_api_type())
+        } else {
+            self.inner.rust_api_type()
+        }
+    }
+
+    fn rust_wire_type(&self) -> String {
+        self.inner.rust_wire_type()
+    }
+
+    fn rust_wire_is_pointer(&self) -> bool {
+        true
+    }
+}