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Date: Fri, 29 Mar 2013 07:47:23 -0700 (PDT)
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Subject: Re: Interresting, possibly buggy behavior in GNAT generics w/
 expression function.
From: Shark8 <onewingedshark@gmail.com>
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Date: 2013-03-29T07:47:23-07:00
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On Friday, March 29, 2013 1:45:04 AM UTC-6, Simon Wright wrote:
> In Generic_Attribute_Set, you have two Image functions:
> 
>     function Image(Value : Attribute_Values) return String
> 
> (Attribute_Values is a generic formal scalar) and
> 
>     function Image(Value : Positive) return String
> 
> and you instantiate the package with Attribute_Values => Integer.
> 
> 
> What happens when you change the second Image's parameter to Integer is
> that GNAT chooses the wrong Image to call!

Yes; hence the 'interesting' and 'possibly buggy'.

> 
> I don't know whether this is a language problem or a GNAT problem. Or,
> of course, a user problem!

This is precisely why I posted it here rather than instantly filing a bug-report.

On the other hand it seems to violate the generic-parameters/principal that we can only apply operations (Attributes and Operations) which the formal is *known* to have.