Re: Elaboration order handling (Was: Bug in 'gnatmake')

[Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>]

On 06/21/2013 08:48 AM, Adam Beneschan wrote:
> On Thursday, June 20, 2013 10:26:14 PM UTC-7, Jeffrey Carter wrote:
>
> Do you do that with empty parameter lists?
>
> procedure Proc_1
>     --(null)
> is ...
>
> How about empty constraints?  The definition of <subtype_indication> is
> [null_exclusion] <subtype_mark> [constraint].  If the constraint is empty,
> shouldn't you have to put something in there to indicate that it's
> deliberately empty?
>
>     I : Integer; --null constraint

None of those are places the language could require a null statement, so I think 
you're comparing apples to oranges.

(By "statement", I mean something with a terminator semicolon that I count as a 
statement when counting statements, which includes declarations. By "null 
statement" I mean a statement identical to Ada's null statement, even if it's a 
declaration. So, yes, the language could require a null statement in a 
declarative part.)

It appears that the language designers considered declarative regions to be 
different enough from executable regions to require null statements in the 
latter and not the former, and most people go along with that without really 
thinking about it. I thought about it and don't see a significant distinction. 
In NINA (a language probably no one will like but me) a declarative part has to 
have at least one declaration, and "null;" must appear if there are no other 
declarations.

-- 
Jeff Carter
"Sheriff murdered, crops burned, stores looted,
people stampeded, and cattle raped."
Blazing Saddles
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