[cxx-interop] Avoid trying to instantiate copy constructor of std::optional<NonCopyable>
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…ptional<NonCopyable>` In libc++, `std::optional` inherits from several mixin base types. Some of those base types do not declare a deleted copy constructor for non-copyable value types, which works fine because clients are not supposed to use those base types directly from C++. Swift, however, imports all of the transitive base types when importing a C++ type. As part of this, ClangImporter will attempt to instantiate e.g. `std::__optional_copy_assign_base<NonCopyable>`, and will fail with a hard error while doing so. rdar://152718041
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In libc++,
std::optionalinherits from several mixin base types. Some of those base types do not declare a deleted copy constructor for non-copyable value types, which works fine because clients are not supposed to use those base types directly from C++.Swift, however, imports all of the transitive base types when importing a C++ type. As part of this, ClangImporter will attempt to instantiate e.g.
std::__optional_copy_assign_base<NonCopyable>, and will fail with a hard error while doing so.rdar://152718041