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From: Blady <p.p11@orange.fr>
Newsgroups: comp.lang.ada
Subject: Re: Aggregate with derived types.
Date: Thu, 14 Sep 2023 22:00:19 +0200
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Le 14/09/2023 à 17:31, Jeffrey R.Carter a écrit :
> On 2023-09-14 16:02, Blady wrote:
>>
>>       1. with Ada.Containers.Vectors;
>>       2. with Ada.Text_IO;
>>       3. procedure test_20230914_derived_agg is
>>       4.    package My_Float_Lists is new Ada.Containers.Vectors 
>> (Positive, Float);
>>       5.    subtype My_Float_List1 is My_Float_Lists.Vector;
>>       6.    type My_Float_List2 is new My_Float_Lists.Vector with null 
>> record;
>>       7.    ML1 : My_Float_List1 := [-3.1, -6.7, 3.3, -3.14, 0.0];
>>       8.    ML2 : My_Float_List2 := ([-3.1, -6.7, 3.3, -3.14, 0.0] 
>> with null record);
>>                                      |
>>          >>> error: no unique type for this aggregate
> 
> IIUC, you have to qualify the value:
> 
> (My_Float_List1'[-3.1, -6.7, 3.3, -3.14, 0.0] with null record)
> 
> or
> 
> (My_Float_Lists.Vector'[-3.1, -6.7, 3.3, -3.14, 0.0] with null record)
> 
> (not tested)

Thanks Jeff, both proposals are compiled ok by GNAT.

I wonder why the float list aggregate isn't inferred by the compiler and 
need some help with a qualification.