Can we just have struct inheritence already?

[Ola Fosheim Grøstad]

On Thursday, 13 June 2019 at 00:18:42 UTC, Timon Gehr wrote:
>> track allocated memory pointers. But that has nothing to do 
>> with undefined values for integers.
>
> Undefined values are not undefined behavior.

Let's try to sort out the terminology, because it seems to cause 
a lot of noise:

Integers don't have undefined values. An integer variable might 
provide an arbitrary value, but  it does not matter what it is if 
you use an algorithm that always multiply by 0 in the first 
iteration then assigns the variable a new value…

If the value was truly undefined, then it could cause undefined 
behaviour, because then the hardware might not have a specified 
consequence for its usage (so it could in theory vary between 
different revisions of the CPU).

But undefined behaviour does not mean that anything can happen, 
it just means that the spec does not say what will happen. The 
hardware vendor or compiler implementor could make that 
deterministic and explicit in the docs.

So, since C is meant to produce fast code for all kinds of 
hardware you have "implementation defined", which means that 
compiler implementors are required to define and document it. 
Then you have "undefined", which means that the implementors are 
not required to define and document it.