We're now one step away from eliminating bare pointers in semantic actions.
There are plenty of other cleanups and modernizations that can be made in the
parser, but the elimination of bare pointers is the one that has the highest
impact for the codebase.
Slowly bringing this into line with Bison's C++ example parser
so we can use strong semantic values for symbols rather than
leaking pointers. First step is to thread a `ParseAndLexContext`
object through the whole syntactic analysis state, like the
example has. In the example, it's called `driver`.
Co-authored-by: Geoff Romer <gromer@google.com>
Jon Meow
Geoff Romer
Dave Abrahams