@printf doesn't handle multi-line strings.

[Ismael-VC]

This doesn't work and I think it would be very handy:

julia> @printf """
               This is a %s
               """ "test"
ERROR: @printf: format must be a plain static string (no interpolation or prefix)


julia> macroexpand(
           quote
               @printf """
                       This is a %s
                       """ "test"
           end
       )
:($(Expr(:error, ErrorException("@printf: format must be a plain static string (no interpolation or prefix)"))))

julia> dump(ans)
Expr 
  head: Symbol error
  args: Array(Any,(1,))
    1: ErrorException 
      msg: ASCIIString "@printf: format must be a plain static string (no interpolation or prefix)"
  typ: Any

How do we define a plain static string?

[ivarne]

Dup of #2682