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From: Stephen Leake <stephen_leake@stephe-leake.org>
Newsgroups: comp.lang.ada
Subject: Re: Ada reference manual rule for doubled parentheses around
 if_expression?
References: <864mkkz2hy.fsf@stephe-leake.org> <87r3nokwpf.fsf@theworld.com>
Date: Sat, 01 Aug 2015 04:11:13 -0500
Message-ID: <86r3nnjrv2.fsf@stephe-leake.org>
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Date: 2015-08-01T04:11:13-05:00
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Bob Duff <bobduff@theworld.com> writes:

> Stephen Leake <stephen_leake@stephe-leake.org> writes:
>
>> I remember seeing some rule in the Ada reference manual that says the
>> doubled parens are not needed here. But now I can't find the rule, and I
>> don't want to edit my grammar without a reference.
>>
>> Anyone know where that rule is? or what to search for?
>
> 4.5.7(7).  This is a syntax rule, despite not being written in BNF.
> I suggest you read the AARM annotations.

Thanks.

There's a similar rule for quantified expressions in 4.5.8(4).

GNAT also accepts this:

   function Expression_Function_1 (V : Integer) return Boolean
     is (V = V and then True)
          or else True;

I think that's a bug, because there are no parens surrounding the
entire expression. 

-- 
-- Stephe