The first release candidate for GCC 6.5 is available from https://gcc.gnu.org/pub/gcc/snapshots/6.5.0-RC-20181019/ ftp://gcc.gnu.org/pub/gcc/snapshots/6.5.0-RC-20181019/
and shortly its mirrors. It has been generated from SVN revision 265300. I have so far bootstrapped and tested the release candidate on x86_64-linux and i686-linux. Please test it and report any issues to bugzilla. If all goes well, I'd like to release 6.5 on Friday, October 26th.