Declarative WASM GC Types

What happened

WASM modules are meant to be parsed and validated very linearly: they list complex types up front, and then refer to them by index inside functions and other key places in the module. Throw in nested structured types with the WASM GC extension, and managing them declaratively becomes a little tough. Recursive type groups are the most difficult to model declaratively!

Summary assembled by rule from the sources below

Sources