Re: proposed @noreturn attribute

[Andrei Alexandrescu via Digitalmars-d]

On 07/08/2017 05:03 PM, Vladimir Panteleev wrote:
On Saturday, 8 July 2017 at 12:17:57 UTC, Andrei Alexandrescu wrote:
    @disable @property None init();

You meant static here I guess.

The compiler detects (without having anything hardwired about the 
particular type "None") that the type None is impossible to create and 
copy/move from a function, and therefore decrees the function will 
never return.

Cheat: https://is.gd/pf25nP

Works because of NRVO I guess. This particular one is countered by also 
adding a disabled destructor.

Eh, interesting. Indeed this doesn't compile anymore:

struct None
{
    @disable this();
    @disable this(this);
        @disable ~this();
    @disable static @property None init();
}

None fun()
{
        None none = void;
        return none;
}

void main()
{
    fun();
}

The type None would then go in object.d.

The compiler detects the pattern and make None implicitly convertible to 
anything so people can write things like:

int x = y ? 100 / y : fun();

Without the conversion, None is a less useful artifact.


Andrei