trait Foo: PartialEq + std::fmt::Debug + Send + Sync { fn a(&self) -> i32 { 10 } fn z(&self) -> i32 { 11 } fn y(&self) -> i32 { 12 } } trait Bar: Foo { fn b(&self) -> i32 { 20 } fn w(&self) -> i32 { 21 } } trait Baz: Bar { fn c(&self) -> i32 { 30 } } impl Foo for i32 { fn a(&self) -> i32 { 100 } } impl Bar for i32 { fn b(&self) -> i32 { 200 } } impl Baz for i32 { fn c(&self) -> i32 { 300 } } fn main() { let baz: &dyn Baz = &1; let bar: &dyn Bar = baz; bar.c(); //~^ ERROR no method named `c` found for reference `&dyn Bar` in the current scope [E0599] let foo: &dyn Foo = baz; foo.b(); //~^ ERROR no method named `b` found for reference `&dyn Foo` in the current scope [E0599] foo.c(); //~^ ERROR no method named `c` found for reference `&dyn Foo` in the current scope [E0599] let foo: &dyn Foo = bar; foo.b(); //~^ ERROR no method named `b` found for reference `&dyn Foo` in the current scope [E0599] foo.c(); //~^ ERROR no method named `c` found for reference `&dyn Foo` in the current scope [E0599] }