8000 🍒[cxx-interop] Do not crash when emitting layout of `std::string` by egorzhdan · Pull Request #81872 · swiftlang/swift · GitHub
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🍒[cxx-interop] Do not crash when emitting layout of std::string #81872

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Merged
merged 1 commit into from
May 31, 2025
Merged

🍒[cxx-interop] Do not crash when emitting layout of std::string #81872

merged 1 commit into from
May 31, 2025

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egorzhdan
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@egorzhdan egorzhdan commented May 30, 2025 •
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  • Explanation: If a [[no_unique_address]] field has zero size according to Clang, and field has a type that isn't representable in Swift, Swift would previously try to add an opaque field of size 1 for it.
    This is wrong and was causing crashes for std::string while emitting a padding field:
_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T1> _LIBCPP_CONCAT3(__padding1_, __LINE__, _);

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@swift-ci please test

@egorzhdan
[cxx-interop] Do not crash when emitting layout of std::string
ee5f7ad 
If a `[[no_unique_address]]` field has zero size according to Clang, and field has a type that isn't representable in Swift, Swift would previously try to add an opaque field of size 1 for it.

This is wrong and was causing crashes for `std::string` while emitting a padding field:
```
_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T1> _LIBCPP_CONCAT3(__padding1_, __LINE__, _);
```

rdar://151941799
(cherry picked from commit a7c1744)
@egorzhdan egorzhdan force-pushed the egorzhdan/6.2-zero-sized-no-unique-address branch from 1b7d221 to ee5f7ad Compare May 30, 2025 16:33
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@swift-ci please test

@egorzhdan egorzhdan marked this pull request as ready for review May 30, 2025 16:53
@egorzhdan egorzhdan requested a review from a team as a code owner May 30, 2025 16:53
@egorzhdan egorzhdan enabled auto-merge May 30, 2025 19:06
@egorzhdan egorzhdan merged commit 3688f6a into release/6.2 May 31, 2025
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@egorzhdan egorzhdan deleted the egorzhdan/6.2-zero-sized-no-unique-address branch May 31, 2025 01:23
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@DougGregor DougGregor DougGregor approved these changes

@j-hui j-hui j-hui approved these changes

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