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From: Bob Duff <bobduff@theworld.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada reference manual rule for doubled parentheses around
 if_expression?
Date: Fri, 31 Jul 2015 14:29:00 -0400
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Date: 2015-07-31T14:29:00-04:00
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Stephen Leake <stephen_leake@stephe-leake.org> writes:

> A question recently came up on the Emacs ada-mode list; my Emacs
> ada-mode parser rejects this if_expression in an association list:
>
>    Tmp : Boolean := Id (if True then True else True);
>
> but accepts this:
>
>    Tmp : Boolean := Id ((if True then True else True));
>
> 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.

- Bob