Deprecate implicit `int` to `bool` conversion for integer literals

[Michael V. Franklin]

On Sunday, 12 November 2017 at 16:57:05 UTC, Andrei Alexandrescu 
wrote:

> A DIP could be formulated to only address the problem at hand. 
> BTW, here's a really fun example:
>
> void fun(long) { assert(0); }
> void fun(bool) {}
>
> enum int a = 2;
> enum int b = 1;
>
> void main()
> {
>     fun(a - b);
> }
>
> The overload being called depends on (a) whether a - b can be 
> computed during compilation or not, and (b) the actual value of 
> a - b. Clearly a big problem for modular code. This is the 
> smoking gun motivating the DIP.

As I understand it, the case above can be solved by changing the 
overload resolution rules without deprecating the implicit 
conversion to bool.  A PR for such a fix was submitted here 
https://github.com/dlang/dmd/pull/1942.

I fear a proposal to deprecate the implicit conversion to bool 
based solely on the example above could be refused in favor of 
overload resolution changes.  IMO, the example above, while 
certainly a smoking gun, is actually just a symptom of the deeper 
problem, so I tried to make that case in the DIP.

The DIP has been submitted here 
https://github.com/dlang/DIPs/pull/99

Perhaps I'm not the right person to be formulating these 
arguments, but given that the issue has been in Bugzilla for 4 
years, I'm probably all you've got.  Sorry.

Mike