[🍒][cxx-interop] Only mark projections of self-contained types as unsafe. #67413
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Projections of trivial types and view types aren't unsafe. This matches what was described in the vision document.
…ift compiler sources changes on it.
…y; fix a few remaining tests that use raw pointers.
…tomatic rac conformance); update tests accordingly.
zoecarver
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| count: count) | ||
| #else | ||
| let buffer = UnsafeBufferPointer<UInt8>(start: _bridged.bytes_begin(), | ||
| count: count) |
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@zoecarver both #if and #else branches seems to have the same code? Did you mean to say _bridged.__bytes_beginUnsafe() in the #else case?
lib/ClangImporter/ClangImporter.cpp
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| // Mark this as safe to help our diganostics down the road. | ||
| if (!cxxRecordReturnType->getDefinition()) { | ||
| return true; | ||
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| if (!hasCustomCopyOrMoveConstructor(cxxRecordReturnType) && | ||
| // A projection of a view type (such as a string_view) from a self | ||
| // contained parent is a proejction (unsafe). |
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Minor typo: "proejction", we can combine the fix with later fixes.
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Description: Projections of trivial types and view types aren't unsafe. This matches what was described in the vision document. A view type like StringRef is already referencing memory it does not own, so if it projects its data again (via the data method for example), there's no additional unsafety. The really unsafe thing is when a self contained (owned) type projects its owned memory because there are subtle difference in C++ and Swift lifetime models (along with different safety expectations). I have discussed with the interop code owners and we all agree that this is the correct change to make. This has been corroborated by feedback from adopters. Finally, this is the behavior that was agreed upon by the workgroup and the broader community and is what is outlined in the forward vision document.
Scope: C++ interop
Risk: Medium. This change will break source. It changes an important part of importing and affects safety. It also has a high risk of breaking parts of the overlay. This change will be hard to walk back if we determine that it is unsafe (for example). It has not been testing with any adopters and this new behavior has not been tested in the wild.
Testing: Unit testing (CI)
Original PR: #67296
Radar: rdar://112220411