Expose fields needed for structured clone

temporal_capi/src/plain_month_day.rs

@@ -87,16 +87,25 @@ pub mod ffi {
         pub fn day(&self) -> u8 {
             self.0.day()
         }
+
         pub fn calendar<'a>(&'a self) -> &'a Calendar {
             Calendar::transparent_convert(self.0.calendar())
         }
 
+        pub fn month(&self) -> u8 {
+            self.0.month_code().to_month_integer()
+        }
+
         pub fn month_code(&self, write: &mut DiplomatWrite) {
             let code = self.0.month_code();
             // throw away the error, this should always succeed
             let _ = write.write_str(code.as_str());
         }
 
+        pub fn reference_year(&self) -> i32 {
+            self.0.reference_year()
+        }
+
         pub fn to_plain_date(
             &self,
             year: Option<PartialDate>,

temporal_capi/src/plain_year_month.rs

@@ -120,6 +120,10 @@ pub mod ffi {
             self.0.era_year()
         }
 
+        pub fn reference_day(&self) -> u8 {
+            self.0.reference_day()
+        }
+
         pub fn calendar<'a>(&'a self) -> &'a Calendar {
             Calendar::transparent_convert(self.0.calendar())
         }