Overloaded iterations with "of"

Help
1

I was pretty happy to use overload functionality of Constant_Indexing with my container:
(Source code available upon request)

4.    package USXStrings is 
5.       type UXString is tagged record 
6.          Data : Wide_Wide_String (1 .. 10); 
7.       end record with 
8.          Constant_Indexing => Get, 
9.          Iterable          => (First => First, Next => Next, Has_Element => Has_Element, Element => Get); 
... 
12.       function Get (Self : UXString; Index : Positive) return Character is (To_Character (Self.Data (Index))); 
13.       function Get (Self : UXString; Index : Positive) return Wide_Character is (To_Wide_Character (Self.Data (Index))); 
14.       function Get (Self : UXString; Index : Positive) return Wide_Wide_Character is (Self.Data (Index)); 
... 
18.    end USXStrings;

Thus I’m able to get the element of the chosen type:

21.    S1, S2, S3 : UXString; 
22.    C          : Character; 
23.    WC         : Wide_Character; 
24.    WWC        : Wide_Wide_Character; 
... 
31.    C   := S1 (3); 
32.    WC  := S1 (2); 
33.    WWC := S1 (1);

Moreover, I want to iterate with “of”:

41.    for CC : Character of S1 loop 
42.       C  := CC; 
43.       F   := CC = 'h'; 
44.       Put_Line (Character'pos (C)'img & F'img); 
45.    end loop; 
46.    for CC : Wide_Character of S2 loop 
47.       WC := CC; 
48.       F   := CC = 't'; 
49.       Put_Line (Wide_Character'pos (WC)'img & F'img); 
50.    end loop; 
51.    for CC : Wide_Wide_Character of S3 loop 
52.       WWC := CC; 
53.       F   := CC = '4'; 
54.       Put_Line (Wide_Wide_Character'pos (WWC)'img & F'img); 
55.    end loop;

But I got errors:

test_uxstrings_2.adb:41:13: error: subtype indication does not match element type "Wide_Wide_Character"
test_uxstrings_2.adb:42:13: error: expected type "Standard.Character"
test_uxstrings_2.adb:42:13: error: found type "Standard.Wide_Wide_Character"
test_uxstrings_2.adb:46:13: error: subtype indication does not match element type "Wide_Wide_Character"
test_uxstrings_2.adb:47:13: error: expected type "Standard.Wide_Character"
test_uxstrings_2.adb:47:13: error: found type "Standard.Wide_Wide_Character"

Only the third loop (line 51) is compiling ok.

Is it a compiler issue or is there something in Ada standard which prevents the two first loops?

2

Maybe I misunderstand your question, but first you have to specify Default_Iterator and Iterator_Element (at least). See RM 5.5.1.