Class vars are still restricted to simple `name: type` bindings, not
full patterns. This is now handled in the check phase instead of during
parsing.
This is in preparation for supporting `static var`.
This includes checking and lowering for concrete form literals. Support
for symbolic forms is future work.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This approach is more robust because there's no intermediate state where
the `ParamPattern` insts have been created, but don't yet have their
final values.
- Explicitly document that `*Param` and `*ParamPattern` insts represent
`Call` parameters.
- Stop wrapping compile-time parameter patterns in `ValueParamPattern`
insts (because they aren't `Call` parameters).
- Document how `MatchContext::results_` relates to the `Call`
parameters, and be more consistent about when it's written to.
- Remove `RuntimeParamIndex::Unknown`: we no longer need to distinguish
"this `Param`'s runtime index is unknown" from "this `Param` isn't a
runtime param", because we no longer use `Param`s at all in the latter
case.
- Rename `RuntimeParamIndex` to `CallParamIndex`.
As a side effect of removing the `ValueParamPattern` insts, this fixes a
minor diagnostic bug where `NoteInitializingParam` didn't identify the
specific parameter that led to a deduction failure, because it expects
generic parameters to only be represented by `SymbolicBindingPattern`s,
but before this change they could be wrapped in `ValueParamPattern`s.
Nicholas Bishop
Geoff RomerandJon Ross-Perkins
