D Logic bug

[Steven Schveighoffer]

On 10/11/18 9:16 PM, Jonathan Marler wrote:
> On Thursday, 11 October 2018 at 23:29:05 UTC, Steven Schveighoffer wrote:
>> On 10/11/18 7:17 PM, Jonathan Marler wrote:
>>
>>> I had a look at the table again, looks like the ternary operator is 
>>> on there, just called the "conditional operator". And to clarify, D's 
>>> operator precedence is close to C/C++ but doesn't match exactly.  
>>> This is likely a result of the grammar differences rather than an 
>>> intention one.  For example, the "Conditional operator" in D actually 
>>> has a higher priority than an assignment, but in C++ it's the same 
>>> and is evaluated right-to-left.  So this expression would be 
>>> different in C++ and D:
>>>
>>
>> Not in my C/D code. It would have copious parentheses everywhere :)
>>
> 
> Good :)

Yep. General rule of thumb for me after having been burned many many 
times -- Always use parentheses to define order of operations when 
dealing with bitwise operations (and, or, xor) and for the ternary operator.

I think I do make an exception when it's a simple assignment. i.e.:

a = cond ? 1 : 2;

> 
>> That case is actually very strange, I don't know if it's something 
>> that's really common.
>>
> 
> Yes, that explains why myself, Jonathan Davis and certainly others 
> didn't know there were actually differences between C++ and D Operator 
> precedence :)  I wasn't sure myself but having a quick look at each's 
> operator precedence table made it easy to find an expression that 
> behaves differently in both.
> 

I actually was curious whether DMC followed the rules (hey, maybe Walter 
just copied his existing code!), but it does follow C's rules.

-Steve