RFC: 2 enhancement DIPs that need feedback

[Basile B.]

On Thursday, 22 May 2025 at 09:31:51 UTC, Basile B. wrote:
> On Wednesday, 21 May 2025 at 04:55:50 UTC, Walter Bright wrote:
>> On 5/14/2025 9:56 AM, Timon Gehr wrote:
>>> Go ahead and implement it. It's harder, not a simplification. 
>>> Suddenly, whenever you are parsing any expression, you will 
>>> have to take into account the possibility that it is actually 
>>> a variable declaration. The way DMD deals with lvalues is 
>>> also ill-equipped to allow this to be added easily. 
>>> Furthermore, you now have to do proper scope handling for 
>>> short-circuiting operations.
>>
>> There's also a problem with handling destruction of the 
>> declaration.
>
> I dont think so. I consider that, based on default 
> initialization, which has to always happen, even if an AndAnd

OrOr

> LHS has evaluated to true and then that the RHS is a 
> VarDeclExp, then its matching variable is always destructible.
>
> To be clear the AST for
>
> ```d
> if (MyStruct ms0 = call0) && (MyStruct ms1 == call1) {}
> ```
>
> is to be thought as
>
> ```d
> {
>     MyStruct ms0; // def init, ms0 is in valid state
>     MyStruct ms1; // def init, ms1 is in valid state
>     if (ms0 = call0) && (ms1 == call1) {}

```d
if ((ms0 = call0) || (ms1 == call1)) {}
```

>     // ...
>     // right before the end of the scope
>     ms0.__dtor();
>     ms1.__dtor();
> }
> ```
>
> In practice that scenario almost never happen, since VarDeclExp 
> are 99% of the time used for pointers or simple numeric types.

plus do people often use `opCast!bool` ?