The IsolatedConformances feature moves to a normal, supported feature.
Remove all of the experimental-feature flags on test cases and such.
The InferIsolatedConformances feature moves to an upcoming feature for
Swift 7. This should become an adoptable feature, adding "nonisolated"
where needed.
Certain dynamic casts cannot work safely with isolated conformances,
regardless of what executor the code runs on. For such cases, reject
all attempts to conform to the type.
There are some configurations where we aren't able to fully
determine whether isolated conformances are supported in the runtime,
so don't check the negative cases.
With the move to explicitly specifying the global actor for an isolated
conformance, we can now have conformances whose isolation differs from
that of the type, including having actors with global-actor-isolated
conformances. Introduce this generalization to match the proposal, and
update/add tests accordingly.
Instead of using the `isolated P` syntax, switch to specifying the
global actor type directly, e.g.,
class MyClass: @MainActor MyProto { ... }
No functionality change at this point
WebAssembly doesn't currently have a good way to install the
"isCurrentGlobalActor" hook on which this checking depends. Disable
the test for the moment.
When establishing whether a given conformance is isolated, look through
the witness tables used to satisfy conditional requirements as well. This
is because an otherwise-nonisolated conditional conformance can become
isolated if one of its associated conformance requirements is satisfied
by an isolated conformance.
While here, make sure this code works with variadic generics, too.
Extend the metadata representation of protocol conformance descriptors
to include information about the global actor to which the conformance is
isolated (when there is one), as well as the conformance of that type to
the GlobalActor protocol. Emit this metadata whenever a conformance is
isolated.
When performing a conforms-to-protocol check at runtime, check whether
the conformance that was found is isolated. If so, extract the serial
executor for the global actor and check whether we are running on that
executor. If not, the conformance fails.
