[6.2] Lower imported C structs and unions as addressable-for-dependencies. #82843
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C code is highly likely to want to use pointers as references between dependent structs, and we would like to be able to readily map these to lifetime-dependent Swift values. Making C types addressable-for-dependencies ensures that any function producing a dependency on such a value receives a stable in-memory address for that value, allowing borrows and inout accesses to always be representable as pointers. rdar://153648393
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@swift-ci Please test |
Xazax-hun
approved these changes
Jul 7, 2025
tbkka
approved these changes
Jul 7, 2025
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@swift-ci Please test Windows |
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@swift-ci Please test Windows |
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Explanation: This causes the compiler to emit imported C types as "addressable-for-dependencies", which ensures we will represent arguments with dependent borrows as pointers, simplifying C interop if we introduce first-class borrows in the future.
Scope: ABI work for future language features.
Issue: rdar://153648393
Original PR: #82707
Risk: Low. No effect on code today; sets up an ABI rule we can take advantage of in future OSes.
Testing: Swift CI
Reviewers: @Xazax-hun