“Out” parameters and destructors

[Nick Treleaven]

On Friday, 14 March 2025 at 07:30:14 UTC, Ogion wrote:
> Functions with `out` parameters simply initialize the parameter 
> with `.init`, instead of properly destroying it.

See https://github.com/dlang/dmd/issues/18348.

I think the solution is to always call the destructor before 
calling the function. However that was not implemented because it 
would break code that uses `S s = void;`, as `s` might not be a 
destructible value. The `= void` case could perhaps be supported 
if the compiler was smart enough to detect simple cases where `s` 
wasn't constructed. In those cases calling the destructor could 
be omitted (the spec might need updating to allow that). Given 
that all this could still break existing code with non-simple 
control flow, it would probably need to be done in the next 
edition rather than current edition of the language.