Swift does not export operator overloads to C++

[nikeokoronkwo]

Description

While compiling a swift module to a C++ library and header file, operator overloads defined on public structs were not exported to C++.

Given the fact that C++ has support for operator overloading similar to how it's done in Swift, I was expecting it would simply be mapped to the C++ header, just like other functionality is. However, that was not the case.

Reproduction

1. Write the following swift code

public struct Vector2D: Vector, TwoDimensional {
    public var x: Float = 0.0, y: Float = 0.0

    public init(_ x: Float, _ y: Float) {
        self.x = x; self.y = y;
    }

    public init(start: Point2D, end: Point2D) {
        self.x = end.0 - start.0
        self.y = end.1 - start.1
    }

    public static func + (left: Vector2D, right: Vector2D) -> Vector2D {
        return Vector2D(left.x + right.x, left.y + right.y)
    }
}

2. Compile the swift code into a clang C++ library

swiftc vector.swift -parse-as-library -module-name Vector -cxx-interoperability-mode=default -emit-clang-header-path Vector.h

3. Use the swift clang code in C++

#include "Vector.h"
#include <iostream>

int main(){
    Vector::Vector2D v = Vector::Vector2D::init(1,2);
    Vector::Vector2D z = Vector::Vector2D::init(2,3);

    Vector::Vector2D x = v + z;
    
    std::cout << x.getX() << std::endl;
}

4. Compile and run the C++ code

clang++ main.cc -L Vector.lib -lVector -std=c++14 -o vector # If on windows add .exe

The final command failed with the following error:

main.cc:8:28: error: invalid operands to binary expression ('Vector::Vector2D' and 'Vector::Vector2D')                             
    8 |     Vector::Vector2D x = v + z;
      |                          ~ ^ ~
1 error generated.

Expected behavior

The following code should work and provide a value of 3

Environment

Swift version 6.0.2 (swift-6.0.2-RELEASE)

Additional information

No response