Foreach problem

[Steven Schveighoffer]

"Denis Koroskin" wrote
> On Sun, 11 Jan 2009 06:04:01 +0300, Tim M <a at b.com> wrote:
>
>> On Sun, 11 Jan 2009 15:59:26 +1300, Tim M <a at b.com> wrote:
>>
>>> On Sun, 11 Jan 2009 15:50:54 +1300, Daniel Keep 
>>> <daniel.keep.lists at gmail.com> wrote:
>>>
>>>>
>>>>
>>>> Tim M wrote:
>>>>>  Why is this an error. Dmd wants to make sure that I declare a new 
>>>>> variable in the foreach statement and not use an existing one?
>>>>>  module test;
>>>>>  void main()
>>>>> {
>>>>>     int i;
>>>>>     int[] nums;
>>>>>     foreach(i; nums)
>>>>>     {
>>>>>         //
>>>>>     }
>>>>> }
>>>>>   dmd test.d
>>>>>  test.d(7): Error: shadowing declaration test.main.i is deprecated
>>>>
>>>> Yes; as the error states, you're not allowed to define variables with 
>>>> the same name as variables in an enclosing scope any more.
>>>>
>>>>    -- Daniel
>>>
>>> Why does it still work for some objects?
>>
>>
>> This works:
>>
>>
>> module test;
>>
>> class A
>> {
>> this()
>> {
>> //
>> }
>> }
>>
>> class B
>> {
>> this()
>> {
>> //
>> }
>>   int opApply (int delegate (inout B) dg)
>>          {
>>                  return 1;
>>          }
>> }
>>
>> void main()
>> {
>> A a;
>> B b;
>> foreach(a; b)
>> {
>> //
>> }
>> }
>>
>
> It is a bug and should be reported.

I'm not so sure.

Would you say this is a bug (it compiles)?

int foo()
{
   int i;
   int innerfoo(int i)
   {
       return i;
   }
   return innerfoo(2); // returns 2
}

because that's basically what a foreach does when using opApply: create an 
inner function and then pass a delegate pointing to that function to 
opApply.

I think the difference between the two is that the compiler handles foreach 
on an array in a special manner without using an inner function/delegate. 
This also fails to compile:

void main()
{
  A a;
  A[] b;
  foreach(a; b)
  {
     //
  }
}