Re: Loop parameter type

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Maxim Reznik <reznikmm@front.ru> writes:

> Hi, All
> 
> Please help me understand Ada name resolution rules for
> loop parameter specification.
> 
> Consider follow code:
> 
>  1: procedure Test is
>  2:    type Int is range 0 .. 1000;
>  3:    C     : Integer := 0;
>  4:    C_Int : Int := 0;
>  5: begin
>  6:    for J in 1 .. 10 loop
>  7:       C := C + J;
>  8:    end loop;
>  9:   
> 10:    for K in 1 .. 10 loop
> 11:       C_Int := C_Int + K;
> 12:    end loop;
> 13: end Test;
> 
> gcc -c test.adb 
> test.adb:11:22: invalid operand types for operator "+"
> test.adb:11:22: left operand has type "Int" defined at line 2
> test.adb:11:22: right operand has subtype of "Standard.Integer" defined
> at line 10
> 
> GNAT complains at line 11, but line 7 seems Ok. Why?

The rule is in RM-3.6(18).  J and K above are both of type Integer, not Int.

IMHO it's a kludge, and you should not rely on it.  Say "for I in
Integer range 1..10" or "for I in Int range 1..10" or whatever.

- Bob