[interop] regression: templated method that returns an owned type is marked as unsafe

[hyp]

After #64300, a C++ method that returns an owned type as a dependent return type in a class template is marked as unsafe.

Example:

struct SWIFT_CXX_IMPORT_OWNED OwnedType {
};

template<class T>
class MyContainer {
public:
  T pop() { ... }
};

using MyContainerOfOwned = MyContainer<OwnedType>; // MyContainerOfOwned.pop is marked as unsafe in Swift.

[AnthonyLatsis]

@hyp I think you pasted in the wrong description. What’s an "owned" type in C++, by the way?

[hyp]

@AnthonyLatsis good catch, fixed. "Owned" type is a classification of a C++ type according to the C++ interoperability vision document: https://forums.swift.org/t/a-forward-vision-for-c-and-swift-interoperability/62150