Comment by unwind

Huh. I thought the article was vague on what exactly these extensions permit, so I'd thought I'd look up the GNU documentation. Surprisingly, it [1] was rather vague too!

The only concrete example is:

Accept some non-standard constructs used in Microsoft header files.

In C++ code, this allows member names in structures to be similar to previous types declarations.

    typedef int UOW;
    struct ABC {
      UOW UOW;
    };

[1]: https://gcc.gnu.org/onlinedocs/gcc/C-Dialect-Options.html#in...