WebAssembly
Allocation of imported types
How does e.g. struct.new work when trying to instantiate an imported struct type? I guess this would need non-abstract type bounds?
Construction will always need a fully defined type, so an import with upper bound won't do, even if that bound was non-abstract — it's not sufficient to know only some of the fields in that situation.
I guess even if the number of fields is the same, you also need to know that their types are not more refined than in the provided arguments.
Right. More abstractly, access is positive/covariant, while construction is negative/contravariant. For the former, an upper bound suffices, while for the latter, you need a lower bound.