We now mark some DeclRefExpr and LookupExprs as implicitly async
during typechecking, depending on whether they appear in a context
that is only performing a read / get operation, and whether they
are cross-actor operations.
also resolves rdar://72403401 by improving the error messages
(no more vague "'await' in async context" when its clearly a call!)
This patch updates the `actor class` spelling to `actor` in almost all
of the tests. There are places where I verify that we sanely handle
`actor` as an attribute though. These include:
- test/decl/class/actor/basic.swift
- test/decl/protocol/special/Actor.swift
- test/SourceKit/CursorInfo/cursor_info_concurrency.swift
- test/attr/attr_objc_async.swift
- test/ModuleInterface/actor_protocol.swift
@actorIndependent is needed on declarations outside of actors to
(e.g.) disable inference of a global actor. It is also effectively the
default, so allow it to be specified explicitly.
Introduce a new attribute `@actorIndependent` that specifies that a
given declaration is considered to be independent of any actor.
Actor-independent declarations do not have access to actor-isolated
state, even when they are declared as instance members of the actor.
On the other hand, actor-independent declarations can be used to
conform to (synchronous) requirements in protocols.
