Why do gcc support empty struct extension for?

[me22]

On Wed, Oct 15, 2008 at 22:02, tiande <tiande@gmail.com> wrote:
>
> struct foo{};
>
> or just
>
> struct bar;
>
> Any example of the usage?
>

Note than those 2 things are completely different.  The former is
useless in C; the latter is not.  (The former is quite common in C++
for tags, especially in the context of template metaprogramming.)