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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: gnoga build fails on Mac
Date: Sun, 21 Jun 2020 10:41:55 +0200
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On 21/06/2020 09:57, Roger wrote:
> Mac Mini (2018)
> OSX 10.15.5
> XCode 11.5
> GNAT  Community Edition 2020
> 
> Attempting to build git clone git://git.code.sf.net/p/gnoga/code gnoga.
> 
> First problem with -gnat05 flag which I overcame but probably not the correct way.
> Second, killer, problem:
> object-handle.adb:153:22: access attribute cannot be used as actual for universal_access equality
> object-handle.adb:163:23: access attribute cannot be used as actual for universal_access equality
> 
> How can I fix this?

GNAT CE 2020 does not accept comparisons like:

    procedure Foo (X : access T) is
    begin
       ...
       if Y'Access = X then
       ...

I cannot say anything about legality of such comparisons, maybe the 
change is related to the upcoming standard, maybe it was never legal.

The latest version 4.50 of the Simple Components fixes the issue by 
replacing access types comparison with by address comparison. [*]

    http://www.dmitry-kazakov.de/ada/components.htm

Replace the offending source files and it should compile again.

-------------------
* I don't know the motivation behind forbidding comparison of access 
attribute, probably some obscure unlikely portability case. Comparing 
addresses would be less safe, for sure, but not much.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de