Use two different nodes for "<type> followed by `as`" and "<type>
omitted before `as`, use `self`", so it is easier to determine which
case. Later the second case will push the type id for `self` onto the
node stack, making the two paths more similar.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
Consume the components of the `impl` declaration, and set up scopes for
the child elements. We don't yet build a representation for the impl
itself.
Also, add an interface type value. This is necessary so that we have a
value for the expression on the right-hand side of `as` in an `impl`.
Goal is to increase type safety, though more work needs to be done (see
added TODOs).
Note that, after this change, check handlers corresponding to deleted
parse node kinds will no longer compile.
---------
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
josh11bandJon Ross-Perkins
Richard Smith
