[cxx-interop] Allow creating Dictionary from std::map
#82817
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rr-codes
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Jul 5, 2025
This adds an initializer to `Swift.Dictionary` that takes an instance of `std::map` or `std::unordered_map`. rdar://155050682
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| self[it.pointee.first] = it.pointee.second | ||
| it = it.successor() | ||
| } | ||
| withExtendedLifetime(dictionary) {} |
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This prevents a use-after-free caused by the compiler destroying dictionary before the end of the block. Unlike C++, Swift doesn't generally have lexical lifetimes, so the compiler is allowed to destroy a variable after its last use. The last use of dictionary here is the call to __endUnsafe(), after which the dictionary might be destroyed, and the iterators will point to invalid addresses.
This kind of issues is why begin() and end() are imported as unsafe methods in Swift, and it's the main reason for providing the Cxx overlay.
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Xazax-hun
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Jul 7, 2025
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This adds an initializer to
Swift.Dictionarythat takes an instance ofstd::maporstd::unordered_map.rdar://155050682