Text_IO.Text_Streams causing errors

Text_IO.Text_Streams causing errors

[Julian Leyh]

Hi, i have some code that looks like this (stripped to minimal
example):

-- bar.adb:
with Foo;
procedure Bar is
   Foobar : aliased Foo.Foobar;
begin
   Foo.Print (Foobar'Access, "Foobar");
end Bar;

-- foo.adb:
with Text_IO.Text_Streams;
package body Foo is
   procedure Print (This : access Foobar'Class; Prefix : in String) is
   begin
      Text_IO.Put_Line (Prefix);
   end Print;
end Foo;

-- foo.ads:
package Foo is
   type Foobar is tagged private;
   procedure Print (This : access Foobar'Class; Prefix : in String);
private
   type Foobar is tagged null record;
end Foo;

Compiling it, I get this error:

foo.adb:3:14: not fully conformant with declaration at foo.ads:3
foo.adb:3:14: type of "This" does not match

If I add -gnat05, the error disappears, and it disappears, too, if I
add the "Ada." prefix to the "with".

I know that I could remove the "Text_Streams", because it is not used
at all, but I'm still a big confused about this error.

Is it a compiler bug or did I do something forbidden?

Tried with compilers GNAT GPL 2010 and GNAT Pro 6.3.1

Re: Text_IO.Text_Streams causing errors

[Adam Beneschan]

On Feb 25, 7:14 am, Julian Leyh <jul...@vgai.de> wrote:
> Hi, i have some code that looks like this (stripped to minimal
> example):
>
> -- bar.adb:
> with Foo;
> procedure Bar is
>    Foobar : aliased Foo.Foobar;
> begin
>    Foo.Print (Foobar'Access, "Foobar");
> end Bar;
>
> -- foo.adb:
> with Text_IO.Text_Streams;
> package body Foo is
>    procedure Print (This : access Foobar'Class; Prefix : in String) is
>    begin
>       Text_IO.Put_Line (Prefix);
>    end Print;
> end Foo;
>
> -- foo.ads:
> package Foo is
>    type Foobar is tagged private;
>    procedure Print (This : access Foobar'Class; Prefix : in String);
> private
>    type Foobar is tagged null record;
> end Foo;
>
> Compiling it, I get this error:
>
> foo.adb:3:14: not fully conformant with declaration at foo.ads:3
> foo.adb:3:14: type of "This" does not match
>
> If I add -gnat05, the error disappears, and it disappears, too, if I
> add the "Ada." prefix to the "with".

and, I assume, changing the procedure call to
Ada.Text_IO.Put_Line(...)

> I know that I could remove the "Text_Streams", because it is not used
> at all, but I'm still a big confused about this error.
>
> Is it a compiler bug or did I do something forbidden?

Compiler bug.  There's certainly no way that adding Ada. to Text_IO
could possibly affect the legality of the "This" parameter.

                      -- Adam