Function init_body_helper 

fn init_body_helper(
    ecx: &ExtCtxt<'_>,
    span: Span,
    primal: Ident,
    new_names: &[String],
    sig_span: Span,
    new_decl_span: Span,
    idents: &[Ident],
    errored: bool,
    generics: &Generics,
) -> (Box<Block>, Box<Expr>, Box<Expr>, Box<Expr>)