[cxx-interop] Zero-initialize C++ structs when calling their default constructors #72903
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…constructors When Swift imports C structs, it synthesizes an initializer that takes no arguments and zero-initializes the C struct. When C++ interop is enabled, Clang treats all C structs as if they were C++ structs. This means that some of the C structs will get a default constructor implicitly generated by Clang. This implicit default constructor will not zero-initialize trivial fields of the struct. This is a common source of confusion and subtle bugs for developers who try to enable C++ interop in existing projects that use C interop and rely on zero-initialization of C structs. rdar://115909532
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When Swift imports C structs, it synthesizes an initializer that takes no arguments and zero-initializes the C struct.
When C++ interop is enabled, Clang treats all C structs as if they were C++ structs. This means that some of the C structs will get a default constructor implicitly generated by Clang. This implicit default constructor will not zero-initialize trivial fields of the struct.
This is a common source of confusion and subtle bugs for developers who try to enable C++ interop in existing projects that use C interop and rely on zero-initialization of C structs.
rdar://115909532