[Bug c++/64956] [5 Regression] __GXX_ABI_VERSION needs a proper definition for the 5.x releases

[doko at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64956

--- Comment #3 from Matthias Klose <doko at gcc dot gnu.org> ---
I found this snippet in one of the xapian headers.

#ifdef __GNUC__
#if __GNUC__ < 3 || (__GNUC__ == 3 && __GNUC_MINOR__ == 0)
#error Xapian no longer supports GCC < 3.1
#else
#if !defined(__GXX_ABI_VERSION) || __GXX_ABI_VERSION != 1002
#error The C++ ABI version of compiler you are using does not match
#error that of the compiler used to build the library. The versions
#error must match or your program will not work correctly.
#error The Xapian library was built with g++ 4.9.1
#endif

my impression was that a value of 999999 means something like
"unstable"/"newest". Assuming that there will be another version, which value
should be chosen for that one?