String copying fails when output from assert

[David Zhang]

On Tuesday, 21 November 2017 at 18:56:03 UTC, Adam D. Ruppe wrote:
> On Tuesday, 21 November 2017 at 18:49:40 UTC, David  Zhang 
> wrote:
>> 	assert(false, chars[0..str.length]);
>> }
>>
>> What am I missing here?
>
> You're escaping a reference to a local variable there. chars[] 
> is a pointer to the stack, which is promptly smashed when the 
> assert error starts working up the call chain, so by the time 
> it actually prints, you have undefined behavior.

So I'd have to allocate the buffer on the heap then...
Is there any way to do this without allocating to the stack?