Error message for unreachable code

[Lionello Lunesu]

Walter Bright wrote:
> Oskar Linde wrote:
>> I see this as an interesting case of where DMD issues an error for 
>> valid code, where a typical C compiler at most would issue a warning. 
>> The generated code (with or without const folding) will be correct. I 
>> would like to hear why DMD considers the above an error while for 
>> instance functions without return values are not.
> 
> It comes about from constant folding. It would be difficult for the 
> compiler to tell that this code is unreachable.

How come? The compiler clearly knows the bounds of x at the instruction 
x[0], so why not constant fold the x.length as well?

L.