Extract doc-comment on plugin functions.

codegen/ui_tests/rhai_fn_duplicate_attr.rs

@@ -0,0 +1,18 @@
+use rhai::plugin::*;
+
+#[export_module]
+pub mod test_module {
+    #[rhai_fn(name = "test")]
+    #[rhai_fn(pure)]
+    pub fn test_fn(input: Point) -> bool {
+        input.x > input.y
+    }
+}
+
+fn main() {
+    if test_module::test_fn(n) {
+        println!("yes");
+    } else {
+        println!("no");
+    }
+}