serde/test_suite/tests/compile-fail/enum-representation/internal-tuple-variant.rs

#[macro_use]
extern crate serde_derive;

#[derive(Serialize)] //~ ERROR: custom derive attribute panicked
#[serde(tag = "type")] //~^ HELP: #[serde(tag = "...")] cannot be used with tuple variants
enum E {
    Tuple(u8, u8),
}

fn main() {}