This refactoring allows us to drop ModuleInterfaceLoader when explicit modules
are enabled. Before this change, the dependencies scanner needs the loader to be
present to access functionalities like collecting prebuilt module candidates.
Tying InputFile to this option meant that every input that was not one of the explictly-blessed kinds was modeled as a Swift file.
With the new InputFile that infers file kinds, we no longer need CompilerInvocation::setInputKind
Prebuilt-module directory now contains a SystemVersion.plist file copied from the SDK
it's built from. This patch teaches the compiler to remark this version and the SDK version
when -Rmodule-interface-rebuild is specified. The difference between these versions could
help us debug unusable prebuilt modules.
In the fast dependency scanner, depending on whether a module intrface was found via the import search path or framework search path, encode into the dependency graph Swift module details, whether a given module is a framework.
Some implicitly imported modules aren't printed in the textual interface file as explicit import,
e.g. SwiftOnoneSupport. We should check implicit imports and add them to the dependency graph.
Since -emit-module-from-interface now emits forwarding modules, explicit module
loader should be able to accept forwarding modules and unbox their actual binary
contents.
-compile-module-from-interface action now takes arguments of -candidate-module-file.
If one of the candidate module files is up-to-date, the action emits a forwarding
module pointing to the candidate module instead of building a binary module.
Instead of replacing an interface file with its up-to-date compile module,
the dep-scanner should report potentially up-to-date module candidates either adjacent to
the interface file or in the prebuilt module cache. swift-driver should later pass down
these candidates to -compile-module-from-interface invocation and the front-end job
will check if one of the candidates is ready to use. The front-end job then either emits a forwarding
module to an up-to-date candidate or a binary module.
For the explicit module mode, swift-driver uses -compile-module-from-interface to
generate modules from interfaces found by the dependency scanner. However, we don't
need to build the binary module if up-to-date modules are available, either adjacent
to the interface file or in the prebuilt module cache directory. This patch teaches
dependencies scanner to report these ready-to-use binary modules.
Expand the FrontendOptions to allow the enabling
of the dependency tracker for non-system
dependencies, and switch the previous clients of
`createDependencyTracker` over to using this
option. This ensures that the dependency tracker
is now set only during `CompilerInstance::setup`.
We will eventually move the protocol entirely to using a JSON file for
explicit Swift modules. Before we finish migrating, we should be forgiving
about using the legacy -swift-module-file argument.
