"A number of issues were raised with the changes to the runtime
library exemption that have caused the release, and a branch that
will allow new development into the GCC tree, to be delayed until
that is resolved. In the meantime, however, GCC development is
hardly standing still, there are numerous interesting ideas
floating around for new features.
"Changing the runtime library exemption was meant to allow the
creation of a plugin API for GCC, so that developers could add
additional analysis or processing of a program as it is being
transformed by the compiler. The Free Software Foundation has long
been leery of allowing such a plugin mechanism because they feared
that binary-only GCC plugins of various sorts might be the result.
In January, though, the FSF announced that it would change the
exemption--which allows proprietary programs to link to the GCC
runtime library--in order to exclude code that has been processed
by a non-GPL "compilation process". It is a bit of license trickery
that will only allow plugins that are GPL-licensed."