pointers, functions, and uniform call syntax

[Era Scarecrow]

On Thursday, 6 September 2012 at 12:00:05 UTC, Artur Skawina 
wrote:
> On 09/06/12 13:34, Era Scarecrow wrote:
>> Alright let's go the opposite direction. Give me an example in 
>> which passing a variable (by reference to a function) would 
>> EVER require it to check the address to see if it was null. 
>> Class/allocated objects should fail before the function gets 
>> control. ie:
>> 
>>  void func(ref int i);
>> 
>>  class X {
>>    int i;
>>  }
>> 
>>  X x;
>>  int* i;
>>  int[10] a;
>> 
>>  func(x.i); /*should fail while dereferencing x to access i,
>>               so never gets to func*/
>>  func(*i);  //does this count as a lvalue? Probably not,
>>  func(a[0]);//none of these three should compile with that in 
>> mind
>>  func(0);
>> 
>> Being named variables, and likely non-classes you are then 
>> left with mostly local variables, or arrays, or some type of 
>> pointer indirection issue. But ever case I come up with says 
>> it would fail before the function was called.
>
> Both '*i' and 'a[0]' count. (Even '0' could be made to work as 
> a 'const ref' arg, but i'm not sure if that would be a good 
> idea)

  I wasn't sure about *i. I can see it going either way. *i would 
need to be dereferenced first, a[0] would need a bounds check 
which then ensures it exists (even if it was dynamic); So 
checking an address from ref wouldn't be needed in the func.