Deprecation message sources

[Jonathan M Davis]

On Tuesday, September 17, 2019 2:34:00 PM MDT Steven Schveighoffer via 
Digitalmars-d-learn wrote:
> On 9/17/19 4:16 PM, Anonymouse wrote:
> > On Tuesday, 17 September 2019 at 19:31:53 UTC, Steven Schveighoffer 
wrote:
> >> I'd hate to say the answer is to special case Nullable for so many
> >> functions, but what other alternative is there?
> >>
> >> -Steve
> >
> > Nullable isn't alone, std.json.JSONType causes a literal wall of text of
> > deprecation warnings.
> >
> > import std.stdio;
> > import std.json;
> >
> > void main()
> > {
> >
> >      writeln(JSONValue.init.type);
> >
> > }
> >
> > https://run.dlang.io/is/J0UDay
>
> I mean, I'm OK with the idea, but having these deprecation messages is
> helping nobody. I can't figure out if there's something I'm supposed to,
> or can, change in order to get rid of them.
>
> There are quite a few places where it is flagging my code for Nullable
> usage without get, and I'm fixing those. But I'll still be left with
> this mess of deprecation messages from Phobos and vibe.d. I don't even
> know where or if it will break once the alias this is removed.

I ran into problems along those lines with dxml recently, and I couldn't
figure out why one of the deprecation messages was being triggered. It
seemed to have to do with isInputRange, but I couldn't figure out where in
my code was resulting in that problem. I tried to track it down by compiling
Phobos with the alias this outright removed from Nullable (with the idea
that I'd then hopefully get some decent error messages wherever the real
problem was), and dxml's tests then compiled and ran just fine with no
deprecation messages. So, I don't know what to do about it. I suspect that
deprecation messages are being triggered simply by code trying to use
Nullable in template constraints rather than just when it's actually used in
proper code, but I don't know.

I ran into problems along those lines when I last tried to deprecate
TickDuration (which is why it's not yet deprecated). Template constraints
were triggering deprecation messages when I didn't think that they should
be, but unfortunately, I didn't have time to narrow down what was going on
so that I could create a proper bug report for it, and I haven't gotten back
to it.

- Jonathan M Davis