error[E0038]: the trait `Bar` cannot be made into an object --> $DIR/object-safety-generics.rs:18:31 | LL | fn make_bar(t: &T) -> &dyn Bar { | ^^^^^^^ `Bar` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit --> $DIR/object-safety-generics.rs:10:8 | LL | trait Bar { | --- this trait cannot be made into an object... LL | fn bar(&self, t: T); | ^^^ ...because method `bar` has generic type parameters = help: consider moving `bar` to another trait error[E0038]: the trait `Bar` cannot be made into an object --> $DIR/object-safety-generics.rs:25:40 | LL | fn make_bar_explicit(t: &T) -> &dyn Bar { | ^^^^^^^ `Bar` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit --> $DIR/object-safety-generics.rs:10:8 | LL | trait Bar { | --- this trait cannot be made into an object... LL | fn bar(&self, t: T); | ^^^ ...because method `bar` has generic type parameters = help: consider moving `bar` to another trait error[E0038]: the trait `Bar` cannot be made into an object --> $DIR/object-safety-generics.rs:20:5 | LL | t | ^ `Bar` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit --> $DIR/object-safety-generics.rs:10:8 | LL | trait Bar { | --- this trait cannot be made into an object... LL | fn bar(&self, t: T); | ^^^ ...because method `bar` has generic type parameters = help: consider moving `bar` to another trait = note: required for the cast from `&T` to `&dyn Bar` error[E0038]: the trait `Bar` cannot be made into an object --> $DIR/object-safety-generics.rs:27:10 | LL | t as &dyn Bar | ^^^^^^^^ `Bar` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit --> $DIR/object-safety-generics.rs:10:8 | LL | trait Bar { | --- this trait cannot be made into an object... LL | fn bar(&self, t: T); | ^^^ ...because method `bar` has generic type parameters = help: consider moving `bar` to another trait error[E0038]: the trait `Bar` cannot be made into an object --> $DIR/object-safety-generics.rs:27:5 | LL | t as &dyn Bar | ^ `Bar` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit --> $DIR/object-safety-generics.rs:10:8 | LL | trait Bar { | --- this trait cannot be made into an object... LL | fn bar(&self, t: T); | ^^^ ...because method `bar` has generic type parameters = help: consider moving `bar` to another trait = note: required for the cast from `&T` to `&dyn Bar` error: aborting due to 5 previous errors For more information about this error, try `rustc --explain E0038`.