why is the behavior of pointers to 0 width doing this?

[Richard (Rikki) Andrew Cattermole]

```d
import std.stdio;

__gshared int literal;

void main() {
     int[0] callstack;
     (&callstack+literal).writeln;
}
```

```asm
_Dmain:
.Lfunc_begin0:
         .file   1 "/" "app/example.d"
         .loc    1 5 0
         .cfi_startproc
         pushq   %rbp
         .cfi_def_cfa_offset 16
         .cfi_offset %rbp, -16
         movq    %rsp, %rbp
         .cfi_def_cfa_register %rbp
         subq    $16, %rsp
         movq    _D7example7literali at GOTPCREL(%rip), %rax
         movslq  (%rax), %rax
         leaq    -4(%rbp), %rdi
         imulq   $0, %rax, %rax
         addq    %rax, %rdi
.Ltmp0:
         .loc    1 7 5 prologue_end
         callq   _D3std5stdio__T7writelnTPG0iZQoFNfQkZv at PLT
         .loc    1 8 1
         xorl    %eax, %eax
         .loc    1 8 1 epilogue_begin is_stmt 0
         addq    $16, %rsp
         popq    %rbp
         .cfi_def_cfa %rsp, 8
         retq
```

Its the famed equation ``ax+b``.

But with ``a * x`` becoming ``0`` by the frontend.