Re: Request for help from the ARG: Static constants

["Randy Brukardt" <randy@rrsoftware.com>]

Tucker Taft has pointed out that I left out the keyword "constant" from my 
test program, which makes a big difference! Please try the corrected program 
below:

> There is a language-lawyer level question that some of the ARG members 
> have been discussing privately for far too long in the past week. An 
> important part of the question is the compatibility effect of changing the 
> rules to match the expectation. As such, I'd like to find out what various 
> compilers do on the following test program. I've tried recent versions of 
> GNAT and Janus/Ada, both of which reject the program citing an error at 
> (2). [This is not supported by the RM wording, BTW.] If you have access to 
> some other Ada compiler, please attempt to compile this program and report 
> the result, either here or to me privately (randy@rrsoftware.com).
>
>                       Randy Brukardt, ARG Editor.
>
> --- Cut here ---

with Ada.Text_IO;
procedure SC is
  Item_Size : constant := 0;
begin
  Ada.Text_IO.Put_Line ("Start Static Constant check");
  if Item_Size > 0 then
     declare
        Length : constant Positive := Item_Size; -- (1)
        type Data_Index is range 1 .. Length; -- (2)
        type Data_Array is array (Data_Index) of Natural;
     begin
        Ada.Text_IO.Put_Line ("Can't get here");
     exception
        when Constraint_Error =>
           Ada.Text_IO.Put_Line ("Can't get here, either");
     end;
  else -- Do nothing
     Ada.Text_IO.Put_Line ("Nothing as expected");
  end if;
  Ada.Text_IO.Put_Line ("End Static Constant check.");
end SC;