On Sun, May 19, 2024 at 11:49 PM Sebastian Wittmeier wrote:
>
> Now exception handling and destruction order should be simple.


Or here's another way of doing it:
    If an exception is thrown and propagates outside of the function,
then all destructors are invoked in the regular order -- except for
the destructor of the return object, which is invoked last.

So then whenever we have a function such as:

struct SomeClass {
  SomeClass(char const*);
  SomeClass(int, double);
   void Eat(void);
   void Drink(void);
};

SomeClass Func(void) _Retvar
{
    SomeClass *p = nullptr;

    std::string str = some_global_variable;

    if ( cond )
    {
        p = &_Retvar{ 5, 2.0 };
    }
    else if ( cond2 )
    {
        str += "frog";
        p = &_Retvar{ str.c_str() };
    }
    else
    {
        return SomeClass( "chocolate" );
    }

    p->Eat();
    p->Drink();
    return _Retvar;
}

It will behave as though you wrote:

SomeClass Func(void) _Retvar
{
    SomeClass *p = nullptr;

    try
    {
        std::string str = some_global_variable;

        if ( cond )
        {
            p = &_Retvar{ 5, 2.0 };
        }
        else if ( cond2 )
        {
            str += "frog";
            p = &_Retvar{ str.c_str() };
        }
        else
        {
            return SomeClass( "chocolate" );
        }

        p->Eat();
        p->Drink();
        return _Retvar;
    }
    catch (...)
    {
        if ( nullptr != p ) p->~SomeClass();
        throw;
    }
}