Detect the bug in the following code

[Idan Arye via Digitalmars-d]

On Thursday, 16 April 2015 at 21:37:39 UTC, deadalnix wrote:
> On Thursday, 16 April 2015 at 13:52:32 UTC, ixid wrote:
>> writeln = "Now this is abused of the syntax."
>
> The important question is, can you assign a tuple and get the 
> auto unpacking to kick in ?

"%s %s".writefln = ("foo".tuple = "bar").expand;