16> func run<T>(_ f: () -> T) -> T { return f() } 17> let foo2 = run { 18. let a = 42 19. let b = "xyz" 20. return Foo(a: a, b: b) 21. } error: repl.swift:17:16: error: unable to infer complex closure return type; add explicit type to disambiguate let foo2 = run { ^ () -> Foo in