trait Foo<'foo>: 'foo {} trait Bar<'bar>: 'bar {} trait FooBar<'foo, 'bar>: Foo<'foo> + Bar<'bar> {} struct Baz<'foo, 'bar> { baz: dyn FooBar<'foo, 'bar>, //~^ ERROR ambiguous lifetime bound, explicit lifetime bound required //~| ERROR lifetime bound not satisfied } fn main() { }