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Date: Tue, 23 Jul 2013 23:46:52 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Subject: Re: What about a Static_Assertion?
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Date: 2013-07-23T23:46:53+02:00
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On 23.07.13 20:07, Yannick Duchêne (Hibou57) wrote:
>
> I believe this would not be too much a nightmare to be added to any Ada 202X, this would just requires a check on the kind of the expression used for the assertion, and failure of a static assertion, could be said to make the compilation to necessary fails.

It should take no more than a little syntax, I think, and
no other changes to compilers are needed, insofar as compilers
have calculated static Boolean expressions for a long time.
The following two static tests builds on discrete_choice_lists
covering all values in type Boolean:

package Static_Assertion is

    Test: constant Boolean := ((not True) or False);
    -- see below

private

    type Check1 (Dummy : Boolean) is
       record
          case Dummy is
             when Test => null;
             when False => null;
          end case;
       end record;

    type Nix is access constant Boolean;
    for Nix'Storage_Size use 0;

    Check2 : constant array (Boolean) of Nix :=
      (Test => null,
       False => null);

end Static_Assertion;

Check2 declares an object, while Check1 does not.