"Blady" <p.p11@orange.fr> wrote in message 
news:b30a173a-fdbf-40b8-8cae-ef71f937e08c@googlegroups.com...
Le mercredi 22 novembre 2017 01:56:29 UTC+1, Randy Brukardt a écrit :
<...>
> Similar issues have occurred for every version of Ada since. (Attempts to
> fix the problem of tagged derived types in generic units among others have
> died because of compatibility concerns. Similarly, my attempt to allow
> untagged type declarations in the private part of protected types seems to
> have died for that reason, even though it's not possible for there to be 
> an
> incompatibility [I think]. I think there is a currently open AI that
> probably will be eventually dropped because of compatibility concerns,
> rather than making it into Ada 2020. And so it goes...)
...
>Here is the Ada standard implementation of some commercial Ada compilers:
>AdaCore: Ada 2012
...
>RR Software: Ada 95 (selected Ada 2007 features)

The 2017 preview also has selected Ada 2012 features [very selected: hardly 
anything got finished in the 2017 development cycle, but the groundwork for 
a lot of things was laid].

The primary reason we haven't done more is limited development resources; 
building big compiler features can take a large amount of development time. 
I suspect that is true for many of the Ada compiler companies.

                                   Randy.