🍒 Diagnose additional @objcImpl member mismatch errors #66149
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@swift-ci please test |
tshortli
approved these changes
May 25, 2023
nkcsgexi
approved these changes
May 25, 2023
Sema now diagnoses @objcImpl implementations with: • The wrong settability (i.e. a `let` used for a `readwrite` property) • The wrong kind (i.e. a method used for a property)
swiftlang#65253 (79e2697) made it so that the async and completion-handler variants of a member would both be matched by the same implementation, but the technique used composes poorly with typechecking work later in this series of commits. Reimplement it so that async variants are filtered out of `ObjCImplementationChecker::unmatchedRequirements` and then async candidates are compared against async alternatives later, during matching.
Check the types of @objcImpl candidates against their requirements and diagnose *most* mismatches. Unlike typical type matching rules, @objcImpl allows an implementation’s parameter *and* result types to be an IUO when the requirement isn’t. This runs against the normal covariance rules in the case of the result type. It’s meant to allow an implementation to handle nils passed to it and return nils even if the declaration formally claims nils are not permitted; this is occasionally necessary to reimplement Objective-C APIs without breaking ABI compatibility. Fixes rdar://102063730.
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Cherry-pick of #66073 to release/5.9:
Explanation:
@_objcImplementationchecking currently does not diagnose some mismatches between the header and extension, such as using a method to implement a property or declaring the wrong types. This PR adds these checks, hopefully improving adopter code quality.Scope: Projects adopting
@_objcImplementationin Swift 5.9, before the feature is official or fully stable.Issue: Fixes rdar://102063730
Risk: Very low. Thanks to #66113, the new diagnostics will be emitted as warnings, so newly-caught mistakes (or new regressions in the diagnostics!) will not prevent adopters from building their projects.
Testing: Includes unit tests; these verify that the new diagnostics are emitted as warnings in release/5.9.
Reviewer: Reviewed by @tshortli on main (except for the last commit, which only adjusts the tests for release/5.9).