Re: Type conversion between access types (was: Free'ing extended types)

[bobduff@world.std.com (Robert A Duff)]

In article <leschkes.832628057@ferret>,
Scott Leschke <leschkes@ferret.cig.mot.com> wrote:
>On a related but different note, I was wondering about the effect of the
>reserved word 'all' in the access type declarations below.  First I was
>slightly surprised that the type conversions in the example code Bob Duff
>posted were allowed since I know that independent access types (even those
>specifying the same type) are viewed as denoting separate pools and as such
>type conversions between them is not allowed.  This rule appears to go out
>the window though if the 'all' modifier is used as in Bob's example.  To
>paraphrase Jerry Seinfeld, "What's the deal with that?"

Yes, if you add the 'all' modifier, the restriction goes "out the
window".  You can convert *to* an 'all' access type, so long as the
designated subtypes match.  But you had better be careful about storage
pools -- if you deallocate from the wrong type, it's erroneous.

>If you remove the 'all's from the declarations, the example ceases to
>compile using GNAT 3.03 SunOS 4.1.3 giving the error message:

Right.

>BTW, If this is by some off chance highlights a bug in GNAT, please accept
>my apologies up front for wasting bandwidth in this forum, but I don't
>believe it is.

I believe GNAT is correct here.

- Bob