byte + byte = int: why?

[Steven Schveighoffer]

On 1/18/19 12:26 PM, Mek101 wrote:
> On Friday, 18 January 2019 at 17:15:09 UTC, Steven Schveighoffer wrote:
>> What is 127 + 127? Answer: 254. Which if converted to a byte is -127. 
>> Not what you might expect if you are doing addition.
> 
> Quite similar to int.max + int.max

Indeed. But this is where C drew the line, so it's where D draws the 
line as well.

>> In fact, D promotes all integral types smaller than int to int to do 
>> arithmetic. And if the result might not fit into what you are 
>> assigning it to, it requires a cast or mask.
> 
> Then why isn't int + int = long? If i did the example above, they 
> wouldn't fit in a int for sure, yet the result is of the same type. Why 
> should byte be any different?

There are other inconsistencies too, like += (which works on byte += byte).

As others have said, those are the rules D has for historical reasons, 
you just have to deal with them.

-Steve