I encountered an issue where allocating memory for a struct with new in the C++ function does not correctly transfer the instance back to C#.

It seems that the correct approach is to avoid using new in the C++ function and directly set the values of the out parameter. However, I couldn’t find documentation that explicitly describes this behavior or explains how out parameters automatically handle instance creation.
Do you have this information somewhere on Microsoft Document?
I would like to know if you know of it.

C++

struct MyStruct {
    int value1;
    float value2;
};

extern "C" __declspec(dllexport) void GetValues(MyStruct* outStruct) {
    // outStruct = new MyStruct();  // NG
    outStruct->value1 = 42;
    outStruct->value2 = 3.14f;
}

C#

[StructLayout(LayoutKind.Sequential)]
public struct MyStruct {
    public int value1;
    public float value2;
}

[DllImport("MyNativeLib.dll", CallingConvention = CallingConvention.StdCall)]
public static extern void GetValues(out MyStruct result);

public static void TestInterop() {
    MyStruct result;
    GetValues(out result);
}