Prior to this change, DDC represented generic classes as closures over type parameters (with type arguments provided at runtime), which tightly coupled generic class definitions with their types and concrete instantiation.
This rewrite decouples this representation, letting us 1) bind type information late and 2) separate generic class definitions from their instantiation.
Notable changes:
- Generic classes are now declared at top level (rather than within in closures).
- RTIs are now passed to generic class constructors at runtime (except for JS Interop classes). Only the instantiated class's RTI is required (and it's retained up the type hierarchy).
- Type signature resolvers are now lambdas that accept a type environment RTI at runtime. While signatures are still attached early, their instances' RTIs are now needed at runtime.
- Generic classes, constructors, and factories are now evaluated in a 'Class' type environment.
- An `RtiTypeEnvironment` is introduced to represent lookups on an RTI type environment bound to a parameter. These are used when evaluating type signatures and at constructor/factory bodies.
- Type recipes now emit Class type parameters with names - but continue to emit method type parameters with de Bruijn indices. This is because indices aren't stable across subtypes.
- Certain debugger functions now require instances (e.g.,`getClassMetadata`).
- Adds a special flag for non-external JS interop factory constructors to emit 'true' types (versus 'any').
Change-Id: I7cbeaaf666dd4f9bd5e3ef22a1163a659fc0ee48
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/365863
Reviewed-by: Srujan Gaddam <srujzs@google.com>
Reviewed-by: Kallen Tu <kallentu@google.com>
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Reviewed-by: Nate Biggs <natebiggs@google.com>
Commit-Queue: Mark Zhou <markzipan@google.com>
MarkZ
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