🍒[cxx-interop] Synthesize a deprecated zero initializer for C++ structs #66268
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When importing a C header in the C++ language mode, Clang/Swift treat C structs as C++ structs. Currently Swift synthesizes a default initializer that zero-initializes the backing memory of the struct for C structs, but not for C++ structs. This is causing issues in existing projects that use C libraries and rely on having the default initializer available in Swift. This change enables the synthesis of a default initializer for C++ structs. Since many C++ structs are not designed to be initialized this way, the initializer is marked as deprecated in Swift. rdar://109727620 (cherry picked from commit fec48f9)
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@swift-ci please test |
DougGregor
approved these changes
Jun 1, 2023
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Explanation: When importing a C header in the C++ language mode, Clang/Swift treat C structs as C++ structs. Currently Swift synthesizes a default initializer that zero-initializes the backing memory of the struct for C structs, but not for C++ structs. This is causing issues in existing projects that use C libraries and rely on having the default initializer available in Swift. This change enables the synthesis of a default initializer for C++ structs. Since many C++ structs are not designed to be initialized this way, the initializer is marked as deprecated in Swift.
Scope: Only takes effect when C++ interop is enabled via a compiler flag.
Risk: Low, this only changes the code path that is specific to C++ interop.
rdar://109727620
(cherry picked from commit fec48f9)