[cxx-interop] Fix lookup of class template instantiations #58543
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To fix a crash during deserialization, we need to store the mangled names of C++ class template instantiations in the lookup table. For example, `std::string` will be serialized as `__CxxTemplateInstNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEEE`, and when another instance of the Swift compiler will later attempt to deserialize a decl referencing this instantiation, it will query the `SwiftLookupTable` for a decl with this name. If this instantiation is not referenced from the module that is currently being compiled, Swift will not instantiate `std::string` during typechecking, and the mangled name will be missing from `SwiftLookupTable`, leading to a deserialization failure. This happens when compiling with cross-module optimization enabled, and the current module does not reference `std::string`, but one of its dependencies does.
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This is a requirement for #42297 |
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@swift-ci please smoke test |
zoecarver
approved these changes
May 3, 2022
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To fix a crash during deserialization, we need to store the mangled names of C++ class template instantiations in the lookup table.
For example,
std::stringwill be serialized as__CxxTemplateInstNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEEE, and when another instance of the Swift compiler will later attempt to deserialize a decl referencing this instantiation, it will query theSwiftLookupTablefor a decl with this name. If this instantiation is not referenced from the module that is currently being compiled, Swift will not instantiatestd::stringduring typechecking, and the mangled name will be missing fromSwiftLookupTable, leading to a deserialization failure. This happens when compiling with cross-module optimization enabled, and the current module does not referencestd::string, but one of its dependencies does.