The second release candidate for GCC 6.1 is available from ftp://gcc.gnu.org/pub/gcc/snapshots/6.0.1-RC-20160423
and shortly its mirrors. It has been generated from SVN revision 235378. 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. We have a P1 AIX bootstrap issue reported, but I haven't managed to reproduce it, so this release candidate does not deal with that. If all goes well, I'd like to release 6.1 next week.
