compile error

[Kalle Olavi Niemitalo]

Kalle Olavi Niemitalo <kon@iki.fi> writes:

> I suggest:
>
>   #include <stdint.h>
>   typedef int64_t _int64;
>   inline uint64_t _byteswap_uint64(uint64_t u) { return __builtin_bswap64(u); }

After posting that, I realized "unsigned _int64" would not be valid
if _int64 is a typedef.  However, GCC 4.7.1 does allow it in C++
(although not in C) and generates the corresponding unsigned type.
Is that another extension?  I didn't find any mention of it among
the C++ extensions in the GCC manual.