I don't see anything in that thread that suggests this is a bug. I think Steve's statement that the limitation can be worked around by using make_variant_over is no longer valid
...and this is the bug (i.e. undesired behavior), isn't it.
since some pretty crucial variant visitation code uses preprocessor metaprogramming and BOOST_VARIANT_LIMIT_SIZE is central to this (take a look at BOOST_VARIANT_VISITATION_UNROLLING_LIMIT in visitation_impl.hpp). Perhaps this is something new since that thread (2008) - however I don't see anything in the release notes from 145 to 147 which would suggest that something changed here (145 is the version I upgraded from when this last worked for me).
Yes, that's what I wrote in the original post (see the link there): some optimization was made in 1.46, it was not reflected in the release notes, and I guess this change caused the issue we're talking about. Maybe Steven could shed some light on this.