Re: Semantics of 'Image and 'Wide_Image on wide enumerations

[Adam Beneschan <adam@irvine.com>]

On Dec 3, 12:56 pm, Adam Beneschan <a...@irvine.com> wrote:
> On Dec 3, 12:25 pm, Michael R <mich...@zanyblue.com> wrote:
>
>
>
>
>
> > Hi Folks,
>
> > I'm trying to figure out how to get wide enumeration types to generate
> > wide images of the values and am not getting results I would expect.
> > Using the simple 'Image, e.g.,
>
> > with Ada.Text_IO;
> > procedure WEnum1 is
> >    use Ada.Text_IO;
> >    type Greek is (α, β, γ);
> > begin
> >    Put_Line ("Alpha is " & Greek'Image (α));
> > end WEnum
>
> > Gives, (possibly encoded?):
>
> > $ gnatmake -gnat05 -gnatW8 wenum1.adb
> > gcc -c -gnat05 -gnatW8 wenum1.adb
> > gnatbind -x wenum1.ali
> > gnatlink wenum1.ali
> > $ ./wenum1
> > Alpha is Α[]
>
> > Using 'Wide_Image gives something more reasonable but not the actual
> > wide characters:
>
> > with Ada.Wide_Text_IO;
> > procedure WEnum2 is
> >    use Ada.Wide_Text_IO;
> >    type Greek is (α, β, γ);
> > begin
> >    Put_Line ("Alpha is " & Greek'Wide_Image (α));
> > end WEnum2;
>
> > $ gnatmake -gnat05 -gnatW8 wenum2.adb
> > gcc -c -gnat05 -gnatW8 wenum2.adb
> > gnatbind -x wenum2.ali
> > gnatlink wenum2.ali
> > $ ./wenum2
> > Alpha is Α
>
> > Is this the expected behaviour?
>
> I think that 'Image, 'Wide_Image, and 'Wide_Wide_Image of enumerations
> (other than character literals) put the output in upper case, where
> there is an upper case.  So what you're seeing is an upper-case alpha,
> which looks just like an A.

I didn't answer all parts of this...  For 'Image, if there are
characters in the image that aren't in the Character type, the result
is implementation-defined.  I don't know if the actual result you're
getting from GNAT has some meaning or is just random or is a bug;
you'd have to ask them.  But yes, the RM here doesn't say specifically
what you should expect, except that it's as least as long as the
'Wide_Wide_Image would be.

The relevant RM sections here are in 3.5, paragraphs 27.5 and 37.

                       -- Adam