Defaut initialization of structs

[Per Nordlöw]

Given a `struct S` is, `S()` always equivalent to `S.init`? I 
wonder which is preferred in an (parameter default value) 
expression that should evaluate to the default value of `S`.

I would like to use `S()` as its shorter to type than `S.init` 
but I'm uncertain whether it can trigger execution of code 
despite D disallows nullary constructors.