The Swift driver (swift/swiftc) is supposed to always be used with an
accompanying SDK, which it derives from the environment. Our test
infrastructure was clearing out this SDK, making it deviate from the
normal operating environment unnecessarily. Switch to providing the
SDK used for building the standard library, which provides a
more-consistent test environment, and tag the few places in tests
where we have explicit dependencies on "no SDK."
Recent-ish SDKs for Darwin platforms include an SDKSettings.json
file with version information and Catalyst SDK version mappings. Read
these (when available) and use them to pass the appropriate SDK
version down to the Darwin linker via `-platform_version`.
Finishes rdar://problem/55972144.
Mac Catalyst was introduced with an iOS deployment target of 13.0.
If given a deployment target before that, adjust the deployment target
to 13.0 for the linker.
Standardize the way in which we pass platform version information to
the Darwin linker, using the `-platform_version` option. In the case
of Mac Catalyst, there may be two such platform arguments.
The eventual point of this refactoring is to also pass information
about the SDK version, which `-platform_version` supports but the
mix of `-*_version_min` parameters do not. For now, the SDK
version is stubbed out to 0.0.0, which is this option's "unknown"
value.
Part of rdar://problem/55972144.
Add support in the driver and frontend for macCatalyst target
targets and library search paths.
The compiler now adds two library search paths for overlays when compiling
for macCatalyst: one for macCatalyst libraries and one for zippered macOS
libraries. The macCatalyst path must take priority over the normal macOS path
so that in the case of 'unzippered twins' the macCatalyst library is
found instead of the macOS library.
To support 'zippered' builds, also add support for a new -target-variant
flag. For zippered libraries, the driver invocation takes both a -target and a
-target-variant flag passes them along to the frontend. We support builds both
when the target is a macOS triple and the target variant is macCatalyst and
also the 'reverse zippered' configuration where the target is macCatalyst and the
target-variant is macOS.
