`import_owned` compiler warnings when building with C++ library

Development C++ interoperability
1

Whenever I compile my Swift 6.1 project that includes a C++ library, I always get lots of these warnings:

<unknown>:0: warning: 'import_owned' Swift attribute ignored on type 'vector': type is not copyable or destructible

If only a few source files are compiled, sometimes I just get a few. When compiling everything clean, however, there are usually over 20 of these printed.

Does anyone know what these warnings mean, and if there's a way to maybe suppress them with SwiftPM?

        .target(name: "CppLib"),
        .target(
            name: "MyApp",
            dependencies: [
                .product(name: "Crypto", package: "swift-crypto"),
                .product(name: "GRPCNIOTransportHTTP2", package: "grpc-swift-nio-transport"),
                .product(name: "GRPCServiceLifecycle", package: "grpc-swift-extras"),
                "CppLib",
            ],
            swiftSettings: [.interoperabilityMode(.Cxx)],
        ),
2

I think @egor.zhdan has fixed this in the Swift 6.2 compiler.

3

Would this be available in the latest Swift 6.2 snapshot?

4

Looks like it's not "fixed", but instead we are getting much more verbose output now with the main-snapshot-2025-06-22:

[#ClangDeclarationImport]: <https://docs.swift.org/compiler/documentation/diagnostics/clang-declaration-import>
/usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/bits/stl_vector.h:389:11: warning: 'import_owned' Swift attribute ignored on type 'vector': type is not copyable or destructible [#ClangDeclarationImport]
 387 |   */
 388 |   template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
 389 |     class vector : protected _Vector_base<_Tp, _Alloc>
     |           `- warning: 'import_owned' Swift attribute ignored on type 'vector': type is not copyable or destructible [#ClangDeclarationImport]
 390 |     {
 391 | #ifdef _GLIBCXX_CONCEPT_CHECKS