Consistent underscores in root directory

test_suite/tests/compile-fail/duplicate-attribute/rename-ser-ser.rs

@@ -0,0 +1,10 @@
+#[macro_use]
+extern crate serde_derive;
+
+#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
+struct S {
+    #[serde(rename(serialize="x", serialize="y"))] //~^^ HELP: duplicate serde attribute `rename`
+    x: (),
+}
+
+fn main() {}