From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
	ip-172-31-74-118.ec2.internal
X-Spam-Level: 
X-Spam-Status: No, score=-2.9 required=3.0 tests=BAYES_00,NICE_REPLY_A
	autolearn=ham autolearn_force=no version=3.4.6
Path: eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail
From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Discriminant problem
Date: Tue, 31 Aug 2021 00:03:16 +0200
Organization: Also freenews.netfront.net; news.tornevall.net;
 news.eternal-september.org
Message-ID: <sgjkj4$kn4$1@dont-email.me>
References: <lytuj8dqya.fsf@pushface.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Mon, 30 Aug 2021 22:03:17 -0000 (UTC)
Injection-Info: reader02.eternal-september.org; posting-host="170b88e280b372a24cf42b600488aae1";
	logging-data="21220"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1/XcLNzxkzWEX+Nuo04lFBIFQkJXpy20uY="
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.11.0
Cancel-Lock: sha1:tggAGy2mMLBVNBBh0H91XvohtXU=
In-Reply-To: <lytuj8dqya.fsf@pushface.org>
Content-Language: en-US
Xref: reader02.eternal-september.org comp.lang.ada:62588
List-Id: <comp.lang.ada>

On 8/29/21 8:51 PM, Simon Wright wrote:
> 
> the compiler says
> 
>     value for discriminant "Node_Test" must be static
>     non-static function call (RM 4.9(6,18))

This has always been the rule for aggregates.

> OK, I get that (tiresome though it is, and I'm amazed I've never come
> across it before), but how to approach it? I seem to be OK with

That is surprising.

>        case Get_Node_Type_Test (T.Node_Type_Part.all) is
>           when Text_Node_Test =>
>              Location_Step.Node_Test :=
>                (Node_Test => Text_Node_Test,
>                 Name      => Null_Unbounded_String);
>           when ...
>        end case;
> 
> but this seems very ugly.

Agreed. What I usually do is

declare
    Result : Whatever (D => Non_Static_Value);
    -- Discriminant of an object need not be static
begin
    Result.F1 := ...;
    ...
    Location_Step.Node_Test := Result;
end;

-- 
Jeff Carter
"You can never forget too much about C++."
115