Looking through Phobos code there's a bunch functions defined with dummy template types:

void whatever(TDummy = void)( int x, ...) //TDummy is never used

Why not just use an empty template parameter list?

void whatever()(int x, ...)


My gut tells me that his is a workaround for an old limitation preventing empty template lists, but figured I'd ask.

On Wednesday, 10 April 2019 at 20:37:38 UTC, Ben Jones wrote:
> Looking through Phobos code there's a bunch functions defined with dummy template types:
>
> void whatever(TDummy = void)( int x, ...) //TDummy is never used
>
> Why not just use an empty template parameter list?
>
> void whatever()(int x, ...)
>
>
> My gut tells me that his is a workaround for an old limitation preventing empty template lists, but figured I'd ask.

It depends on the specific function, but there's lots of old code in Phobos. In this case it could be that it was a workaround for a DMD bug or limitation that has since been fixed.

So never be afraid to question Phobos code and give it the full scrutiny it needs.

A good rule of thumb is that if all unittests still pass, the reason was historic ;-)