bool <=> int. WTF. (DIP0015)

[Jonathan M Davis]

On Tuesday, July 2, 2019 11:43:27 AM MDT Les De Ridder via Digitalmars-d 
wrote:
> On Tuesday, 2 July 2019 at 17:04:24 UTC, Jonathan M Davis wrote:
> > On Tuesday, July 2, 2019 6:06:00 AM MDT a11e99z via
> >
> > Digitalmars-d wrote:
> >> [...]
> >
> > Basically, unlike most of us, Walter doesn't see any real
> > difference between a bit and a bool even conceptually and thus
> > thinks bool should just be a one bit integer type. So, for the
> > most part, that's actally how bool works in D. At some point,
> > either someone convinced him to make ++ illegal on bools or
> > managed to get a PR in that did, and as I understand it, he
> > regrets that that happened. DIP 1015 was proposed to fix how
> > bool works so that it's no longer treated like an integer type,
> > but Walter and Andrei rejected it. It's been discussed to death
> > already, and it's clearly not going to change. As is the case
> > with many (most?) languages, ultimately, language decisions in
> > D are not a democracy. D is Walter's language, and he has the
> > final say. He frequently has made great decisions with D. Many
> > of us do not think that he did in particular this case, but
> > it's still his decision, and it's quite clear at this point
> > that he's not going to change his mind on this topic. So, if
> > you want to use D, you're basically just going to have to learn
> > to put up with the idea that bool is effectively bit.
> >
> > - Jonathan M Davis
>
> I'm new to this discussion, but:
>
> Can we fix the implementation and the spec, then? Walter's
> opinion is
> clear, so can we move on? People are still free to write a new
> DIP to
> convince the language maintainers, but the current state of bool
> seems
> inconsistent.
>
> This is in the spec[1] but fails for bool:
>
>      assert(T.max + 1 == T.min, T.stringof);
>      assert(T.min - 1 == T.max, T.stringof);
>
> The spec also doesn't[2] consider `true` and `false` to be integer
> literals, yet they are of type bool and they can be used as the
> rhs of
> an int assignment. The grammar currently doesn't even consider
> them to
> be literals[3].
>
> Why do complement expressions[4] not work on bool?
>
> To me something feels clearly wrong here.
>
> [1] https://dlang.org/spec/expression.html#add_expressions
> (paragraph 7)
> [2] https://dlang.org/spec/lex.html#IntegerLiteral
> [3] https://dlang.org/spec/grammar.html#PrimaryExpression
> [4] https://dlang.org/spec/expression.html#complement_expressions

I don't know exactly what the spec should say. Depending on what the issues
are, fixing it could require Walter's input, but there's no question that
the spec needs to say exactly how things work, and it's possible that some
implementation changes would be merited to make things more consistent even
if it doesn't involve fixing bool the way many of us would like (though
implementation changes quickly get into DIP territory). Walter and Andrei
have already talked about how the spec needs to be improved such that it's
more on par with what you have with a language like C++, but specs really
aren't something that Walter's good at, which is a lot of why we don't have
a better spec. So, if you have improvements for the spec, feel free to
create PRs.

- Jonathan M Davis