DIP 1015--removal of implicit conversion from integer and character literals to bool--Community Review Round 1

[Jonathan M Davis]

On Wednesday, June 20, 2018 08:16:21 Mike Parker via Digitalmars-d wrote:
> This is the feedback thread for the first round of Community
> Review for DIP 1015, "Deprecation and removal of implicit
> conversion from integer and character literals to bool":
>
> https://github.com/dlang/DIPs/blob/7c2c39243d0d747191f05fb08f87e1ebcb575d8
> 4/DIPs/DIP1015.md
>
> All review-related feedback on and discussion of the DIP should
> occur in this thread. The review period will end at 11:59 PM ET
> on July 4, or when I make a post declaring it complete.
>
> At the end of Round 1, if further review is deemed necessary, the
> DIP will be scheduled for another round. Otherwise, it will be
> queued for the Final Review and Formal Assessment by the language
> maintainers.
>
> Please familiarize yourself with the documentation for the
> Community Review before participating.
>
> https://github.com/dlang/DIPs/blob/master/PROCEDURE.md#community-review
>
> Thanks in advance to all who participate.

I think that this is a fantastic idea and that experience has shown that on
the whole, the implicit conversion to bool causes far more bugs than it
fixes and that the annoyance that the extra explicit casts would cause do
not outweigh how error-prone it is for most programmers. So, I'm very much
behind this.

The only improvement I can think of is what Steven pointed out about
conditionals. Technically, conditionals are implicit, explicit casts (in
that the compiler inserts an explicit cast for the programmer). So,
something like

while(1)

is lowered to

while(cast(bool)1)

and does not actually rely on implicit conversions. That's why something
like

if(auto value = key in aa)

works, whereas

bool present = key in aa;

doesn't. However, that's not clear to everyone, and so the DIP should be
clear that it does not affect conditionals, since in those cases, the
compiler inserts an explicit casts. The DIP just puts integer and character
literals in the same boat as something like string literals in that

if("foo")

compiles just fine, whereas

bool b = "foo";

does not.

- Jonathan M Davis