Re: Representation clause

["Ken Garlington" <Ken.Garlington@computer.org>]

"David C. Hoos, Sr." <david.c.hoos.sr@ada95.com> wrote in message
news:CQdm6.136516$Ch.25230662@newsrump.sjc.telocity.net...

: The fact that a given compiler may do reasonable things when the
: sizes of the actual parameters of an instantiation of
: Ada.Unchecked_Conversion are unequal, is not a property on
: which I would like to depend.  However, since there is at least one
: compiler for which my comment is not true, I have modified my
: comment to read as follows:
:
:    -- The enumeration's 'Size attribute must be the same as that of
:    -- the representation type, else the effect is implementation-
:    -- defined; in particular, the result can be abnormal (see
:    -- RM95 13.9.1).

Certainly, you don't want to depend upon that behavior, and the comment is
better. I am curious about the interpretation of the ARM in one area,
however. 13.3:47 and 13.9:4 seems to guarantee that we can depend on 'Size
applied to the subtype being honored by the Unchecked_Conversion  *source*
parameter; are there any issues with the *target* object not being the same
'Size as its subtype? If the intent is to point out that there are
restrictions related to the underlying dependence on Unchecked_Conversion, a
reference to 13.9:5-11 would seem more appropriate. In fact, 13.9:9 might
imply that you could _never_ depend upon this working...