error[E0119]: conflicting implementations of trait `std::ops::FnOnce<()>` for type `&_`: --> $DIR/incoherent-assoc-imp-trait.rs:13:1 | LL | impl FnOnce<()> for &F { | ^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: conflicting implementation in crate `core`: - impl FnOnce for &F where F: Fn, F: ?Sized; error[E0210]: type parameter `F` must be used as the type parameter for some local type (e.g., `MyStruct`) --> $DIR/incoherent-assoc-imp-trait.rs:13:6 | LL | impl FnOnce<()> for &F { | ^ type parameter `F` must be used as the type parameter for some local type | = note: implementing a foreign trait is only possible if at least one of the types for which it is implemented is local = note: only traits defined in the current crate can be implemented for a type parameter error: aborting due to 2 previous errors Some errors have detailed explanations: E0119, E0210. For more information about an error, try `rustc --explain E0119`.