Use the `%target-swift-5.1-abi-triple` substitution to compile the tests for
deployment to the minimum OS versions required for use of _Concurrency APIs,
instead of disabling availability checking.
Add specific deployment target versions to some tests that need to test
10.x-specific behaviours and are currently depending on the default
deployment target.
Certain tests were only checking either the stable or unstable ABI
depending on the platform the test was running. In those cases I doubled
up the checks so that we would test both cases on platforms that
supported it. This might use a bit of extra time on targets that only
support the stable ABI, but it seemed worth it for the additional
coverage in CI.
This change introduces a new compilation target platform to the Swift compiler - visionOS.
- Changes to the compiler build infrastrucuture to support building compiler-adjacent artifacts and test suites for the new target.
- Addition of the new platform kind definition.
- Support for the new platform in language constructs such as compile-time availability annotations or runtime OS version queries.
- Utilities to read out Darwin platform SDK info containing platform mapping data.
- Utilities to support re-mapping availability annotations from iOS to visionOS (e.g. 'updateIntroducedPlatformForFallback', 'updateDeprecatedPlatformForFallback', 'updateObsoletedPlatformForFallback').
- Additional tests exercising platform-specific availability handling and availability re-mapping fallback code-path.
- Changes to existing test suite to accomodate the new platform.
Adds two new IRGen-level builtins (one for allocating, the other for deallocating), a stdlib shim function for enhanced stack-promotion heuristics, and the proposed public stdlib functions.
