[Feature] Support dynamic-style overload for FFI object types

[DarkSharpness]

Related discussion here #265 .

Modification in short:

1. Add Function::FromPackedInplace in function.h and generalize some methods in registry.h
2. Implement FFI object types overload method (all in extra/overload.h)
3. Add a simple test.

[gemini-code-assist]

Summary of Changes

Hello @DarkSharpness, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the Foreign Function Interface (FFI) by implementing dynamic-style function overloading for object types. This feature allows developers to define multiple C++ methods or constructors with identical names but distinct parameter lists, which can then be seamlessly invoked from FFI bindings. The change improves the usability and expressiveness of FFI object definitions, making them more aligned with standard C++ programming patterns.

Highlights

• Dynamic Overloading for FFI Objects: Introduced a new mechanism (OverloadObjectDef) to support dynamic-style overloading for methods and constructors of FFI object types, allowing multiple functions with the same name but different argument signatures.
• Function::FromPackedInplace Addition: Added a new static method Function::FromPackedInplace to function.h, which enables creating a ffi::Function and simultaneously obtaining a pointer to its internal callable, essential for managing overloaded functions.
• Generalized Function Wrapping: Refactored ReflectionDefBase in registry.h to generalize the WrapFunction and GetMethod utilities, making them more flexible and compatible with the new overloading infrastructure.
• New Test Coverage: Included a new test file (test_overload.cc) to thoroughly validate the functionality of overloaded constructors, instance methods, and static methods for FFI objects.

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[gemini-code-assist]

Code Review

This pull request introduces a powerful feature to support overloading of FFI object methods, including constructors, instance methods, and static methods. The implementation is well-designed, with good attention to performance by minimizing virtual function calls. The changes are well-structured, with the core logic encapsulated in the new include/tvm/ffi/extra/overload.h header, and necessary supporting changes made to function.h and registry.h. The addition of tests in tests/cpp/test_overload.cc is great and covers the primary use cases. I have a couple of minor suggestions for improvement.

[gemini-code-assist]

The file path in this comment is incorrect. It appears to be a copy-paste error and should be updated to reflect the correct file path.

 * \file tvm/ffi/extra/overload.h

[gemini-code-assist]

The current error message for a failed overload resolution is quite generic. To improve debuggability, consider enhancing the error message to include more context, such as the argument types that were provided and a list of the available overloads with their signatures. This would make it much easier for users to identify why a call failed to match any overload.

[junrushao]

I suppose it's fine to wildcard include sstream without the guards?

[DarkSharpness]

Wildcard include sstream is not friendly to clangd, which gives me an annoying warning "Included header sstream is not used directly". It's just a style fix and could be removed.

[junrushao]

I see.

I’ve got bunch of similar warnings too. I managed to run clangd on this repo on mainline CI, but it only applies to .cc files instead of headers. If you have any ideas how to improve, I’m happy to walk you through what the existing infra looks like.