swift

69d4e940 - [5.7] Fix issues blocking enablement of `-target-min-inlining-version min` (#59176)

[5.7] Fix issues blocking enablement of `-target-min-inlining-version min` (#59176) Cherry-pick and squash of the following PRs to release/5.7: #42585 #58417 #58654 #58680 #58707 #58870 #58963 #59040 #59065 * Sema: Fix `isExported()` for extension decls in order to correct availability diagnostics when `-target-min-inlining-version min` is specified. Resolves rdar://91382040 * Sema: Avoid diagnosing potential unavailability of type components (extension nominal type, superclass, etc.) on declarations that are explicitly unavailable. Resolves rdar://92179327 * Sema: Downgrade diagnostics about potential unavailability of the extended type in an extension declaration when the following conditions are met: 1. The extension is missing explicit availability. 2. The required availability is before the deployment target. Resolves rdar://92621567 * NFC: Expand `-target-min-inlining-versiong` tests to cover a number of corner cases: - unavailable declarations and unavailable containers - SPI declarations and spi containers - property initializer expressions - property wrappers * Sema: When computing potential unavailability of a decl, first check whether the decl is explicitly unavailable and the context is also unavailable. If those conditions are met, treat the decl as if it were always available since unavailable code is allowed to reference unavailable decls. Resolves rdar://92551870 * Sema: Use the deployment target when checking availability for SPI and unavailable API declarations with `-target-min-inlining-version min` specified. There's not much benefit to more accurate enforcement of availability in these decls since API clients can't use them and there's a lot of existing code that would be needlessly diagnosed without these exceptions. Resolves rdar://92716633 * Sema: Teach the compiler to refine `VarDecl` initializer expressions using the deployment target when the init would not be exposed to module clients. Without this, the initializers of public properties in API modules could be misdiagnosed as potentially unavailable to clients of the module, even though the expression will only ever execute on the deployment target or higher. Resolves rdar://92713589 * Tests: Update `attr_inlinable_available.swift` to require macOS and remove the OS versions for other platforms from availability attributes. * Tests: Add test cases for potential unavailability in class inheritance when is specified. * Sema: Reword diagnostics about potentially unavailable decls to improve clarity for authors of API libraries. When decls are diagnosed as potentially unavailable on an OS earlier than the deployment target, the message will now indicate that the issue would be faced by clients of the module. Resolves rdar://93466875 * Sema: Use the availability of the extended nominal as a floor for the availability of extensions. The primary motivation for this change is to reduce unnecessary availability diagnostics for API library authors. Many API libraries contain existing extension decls that lack declared availability where the extension introduces additional members to the extended type in the same release that the extended type was declared. Others contain extensions where the extension itself does not have declared availability but each of the members do. In both cases, the code is safe as written so the extra diagnostics would be a nuisance. Resolves rdar://93630782 * Sema: Downgrade diagnostics about inheritance from a less available type when `-target-min-inlining-version min` is specified. As a concession to source compatibility for API libraries, downgrade diagnostics about inheritance from a less available type when the following conditions are met: 1. The inherited type is only potentially unavailable before the deployment target. 2. The inheriting type is `@usableFromInline`. Resolves rdar://92747826