First Draft: opUnwrapIfTrue

[Dennis]

On Thursday, 26 February 2026 at 13:53:41 UTC, Richard (Rikki) 
Andrew Cattermole wrote:
> ```D
> if (int value = result) {
>     // got a value!
>     assert(value == 99);
> } else {
>     // oh noes an error or default init state
> }
> ```

So after this DIP, the value in the if-condition can now be 
falsey.

```D
if (int value = result)
{
     // value can be 0 here
     assert(value); // can fail!
}
```

This looks very confusing to me. Note that Rust's `if let 
Some(value) = result
` doesn't have this problem because the `Some()` makes it 
explicit that unwrapping is going on. (Also int/i32 doesn't 
implicitly convert to bool there).

You list range primitives as prior work, but notably they require 
the dedicated foreach keyword instead of being an invisible 
overload of the old `for` statement. I think if we add unwrapping 
or pattern matching to D, it should have its own syntax.