Re: Rosetta Code task Proper divisors fails to compile

[Kenneth Wolcott <kennethwolcott@gmail.com>]

On Wednesday, July 26, 2023 at 12:57:40 PM UTC-7, Jeffrey R.Carter wrote:
> On 2023-07-26 20:30, Kenneth Wolcott wrote: 
> > 
> > Thank you for your suggestion. Doesn't seem to have any effect.
> Interesting. I get the same results with GNAT 12. 
> 
> Looking more closely at the code, I think the error, while its msg is 
> misleading, is correct. A function that returns a limited type can only return 
> an aggregate, a function call, or an object declared by an extended return 
> statement. The generic formal object None is none of these. 
> 
> Changing the generic parameter to a function 
> 
> with function None return Result_Type; 
> 
> makes the code correct. You need to change the definition of Empty in 
> Proper_Divisors 
> 
> function Empty return Pos_Arr is (1 .. 0 => <>); 
> 
> and create a function to supply for the 2nd instantiation 
> 
> function None return Natural is (0); 
> ... 
> package Divisor_Count is new Generic_Divisors 
> (Result_Type => Natural, None => None, One => Cnt, Add => "+"); 
> 
> and then it compiles and runs. 
> 
> Another possibility is to make Result_Type simply private, though that is 
> slightly less general. That may be how the OP got the code to compile and run. 
> It might be that limited was added later because the OP saw that it could be, 
> and never tested the change.

Hi Jeff;

  Thank you for your reply.

  I went with the latter suggestion for my local use.

Ken