rust/tests/ui/marker_trait_attr/overlap-marker-trait.rs

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// Test for RFC 1268: we allow overlapping impls of marker traits,
// that is, traits with #[marker]. In this case, a type `T` is
// `MyMarker` if it is either `Debug` or `Display`. This test just
// checks that we don't consider **all** types to be `MyMarker`.
#![feature(marker_trait_attr)]
use std::fmt::{Debug, Display};
2022-10-26 21:11:49 -05:00
#[marker]
trait Marker {}
impl<T: Debug> Marker for T {}
impl<T: Display> Marker for T {}
fn is_marker<T: Marker>() { }
struct NotDebugOrDisplay;
fn main() {
// Debug && Display:
is_marker::<i32>();
// Debug && !Display:
is_marker::<Vec<i32>>();
// !Debug && !Display
is_marker::<NotDebugOrDisplay>(); //~ ERROR
}