This enables us to stop using `Env` in the typechecker. As a byproduct, this commit also restructures the interpreter to handle run-time global initialization as part of ordinary execution, using the Action stack.
This required changing BindingPattern::name() to return `"_"` instead of nullopt when representing a `"_"` binding.
Semi-related drive-by fixes:
- Update BindingPlaceholderValue to expose a NamedEntity instead of a string name, and stop exposing its type.
- Drop the unused SourceLocation parameter of ValueEqual
As a byproduct, replace NamedEntity with a type-erasing wrapper NamedEntityView, eliminate virtual inheritance from the AST, and eliminate interfaces from gen_rtti.
This doesn't actually use the results of name resolution, but it does verify that they are present.
Also ensures that name resolution and type checking are applied to deduced function parameters and the implicit call to `Main()`.
Co-authored-by: Jon Meow <46229924+jonmeow@users.noreply.github.com>
This starts detecting naming collisions as a consequence of being able to determine when the name is declared twice in a given scope.
Co-authored-by: Geoff Romer <gromer@google.com>
Geoff Romer
Jon Meow