Were using bison 3 for a best quality. See D357.

We will have to wait until Bison 3 is a mainstream.

It's potentially available on windows (not officially): https://github.com/lexxmark/winflexbison. Also not all Linuxes have this bison version.

Update (Feb 2018): winflexbison is 3.0.4 now (see here) so there's chance for Windows support.