trait A { fn hello(&self); } trait B { fn test_1(&self) -> &impl A; fn test_2(&self) -> &dyn A; } struct C { } impl A for C { fn hello(&self) { } } impl B for C { fn test_1(&self) -> &impl A { self } fn test_2(&self) -> &dyn A { self } } fn test() { let c = C{}; c.test_1().<1>; // no hello() completion c.test_2().<2>; // hello() part of code suggestions c.test_1().hello(); // properly resolved  c.test_2().hello(); // properly resolved }