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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: GNAT CE 2020 : error when using anon access to subprogram inside
 protected !?
Date: Tue, 02 Jun 2020 13:04:05 +0100
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Date: 2020-06-02T13:04:05+01:00
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Jérôme Haguet <j.haguet@cadwin.com> writes:

> When I start testing existing code with GNAT CE 2020, I faced a
> compilation error when using anonymous access to subprogram inside
> protected body.

> pb20200602.adb:27:18: subprogram "Do_On_Item" has wrong convention
> pb20200602.adb:27:18: does not match access to subprogram declared at line 7
>
>
> package Pb20200602 is
>    protected Tokens is 
>       procedure Call_Walker;    
>    end;
> end;
>
> --  ---------------------------------------------------------------------
> with Ada.Text_Io;
> package body Pb20200602 is
>
>    protected body Tokens is
>
>       procedure Walker
>         (On_Item : not null access procedure (Name    : String);
>          Success : out Boolean
>         )
>       is
>       begin
>          On_Item.all ("John Doe");
>          On_Item.all ("Jane Doe");
>          Success := True;
>       end;
>
>       procedure Call_Walker
>       is
>          procedure Do_On_Item (Name      : String)
>          is
>          begin
>             null;
>          end;
>          Success : Boolean := False;
>       begin
>          Walker (Do_On_Item'Access,
>                  Success);
>          if Success then
>             Ada.Text_Io.Put_Line ("Success!");
>          end if;
>       end;
>
>    end;
>
> end;

I'm amazed that you can declare Walker inside the PO!

CE 2020 will compile this without complaint if you move Walker outside
the PO.