Parentheses around conditional/quantified expressions

Parentheses around conditional/quantified expressions

[Georg Bauhaus]

The following source text is not accepted by GNAT:

package Instance is new Generic (for Some J in 1 .. 10 => True);

where generic package Generic has a single Boolean formal
parameters. GNAT says, "quantified expression must be parenthesized"
Are parentheses needed, or does GNAT just not support this case yet?

LRM 4.5.7 and 4.5.8 say, respectively,

"Wherever the Syntax Rules allow an expression,
 a conditional_expression may be used in place of the expression,
 so long as it is immediately surrounded by parentheses."

"Wherever the Syntax Rules allow an expression,
 a quantified_expression may be used in place of the expression,
 so long as it is immediately surrounded by parentheses."

GNAT does accept:

package Instance is new Generic ((for Some J in 1 .. 10 => True));

Re: Parentheses around conditional/quantified expressions

[Marc C]

On Monday, October 8, 2012 6:26:06 AM UTC-5, Georg Bauhaus wrote:
> The following source text is not accepted by GNAT:
> 
> package Instance is new Generic (for Some J in 1 .. 10 => True);
> 
> where generic package Generic has a single Boolean formal
> parameters. GNAT says, "quantified expression must be parenthesized"
> Are parentheses needed, or does GNAT just not support this case yet?

> GNAT does accept:
> 
> package Instance is new Generic ((for Some J in 1 .. 10 => True));

I can't speak to the validity of this construct, but if it does turn out to be valid code that GNAT is rejecting, report it to them. Even as an unsupported user they'll accept bug reports, and *may* respond.

AdaCore has conceded that some of the 2012 features implemented in GNAT GPL 2012  have some bugs (http://identi.ca/conversation/94802814#notice-95432414), though everything I've reported so far they've said has been fixed in their current baseline. Just gotta wait for GNAT GPL 2013 :-)

Marc A. Criley