Thread the static build configuration (formed from language options) in
to the macro plugin handler, which will serialize it for use in the
macro implementation. test this with a simple macro that checks
whether a particular custom configuration (set via `-D`) is enabled or
not.
This required some re-layering, sinking the logic for building a
StaticBuildConfiguration from language options down into a new
swiftBasicSwift library, which sits on top of the C++ swiftBasic and
provides Swift functionality for it. That can be used by the C++
swiftAST to cache the StaticBuildConfiguration on the ASTContext,
making it available for other parts of ASTGen.
a predicate.
The new overload is used during macro expansion to find the nearest
syntax node that is either a `DeclSyntax` or a `ClosureExprSyntax`.
This avoids an issue where calling the overload that accepts a
specific type may find an outer, unrelated declaration or closure.
We introduce a new macro called #SwiftSettings that can be used in conjunction
with a new stdlib type called SwiftSetting to control the default isolation at
the file level. It overrides the current default isolation whether it is the
current nonisolated state or main actor (when -enable-experimental-feature
UnspecifiedMeansMainActorIsolated is set).
