struct Example
{
    private void helper(int i, this X)() { }
    void funcTempl(T, this X)(T value)
    {
        this.helper!0();
    //  ^^^^^ Why do I need this?
    }
}

void main()
{
    auto ex = Example();
    ex.funcTempl(1);
}

The question is in the comment in the code. Is that intentional or a bug?

On Wednesday, 30 October 2019 at 20:22:25 UTC, Q. Schroll wrote:
> struct Example
> {
>     private void helper(int i, this X)() { }
>     void funcTempl(T, this X)(T value)
>     {
>         this.helper!0();
>     //  ^^^^^ Why do I need this?
>     }
> }
>
> void main()
> {
>     auto ex = Example();
>     ex.funcTempl(1);
> }
>
> The question is in the comment in the code. Is that intentional or a bug?

It's a bug - filed as https://issues.dlang.org/show_bug.cgi?id=20341.

However, note that typeof(this) inside funcTempl() is different from X, so that inside helper(), X will not be the same as in funcTempl(). To fix this, you will need to pass X on to helper as helper!(0, X). When you do this, you no longer need 'this.' in front of the instantiation.

--
  Simen