Csharp 为什么 C# 允许在具有约束 INumber 的泛型类中使用 + 运算符，而 VB.NET 不允许

首先，我目前正在使用VB.NET，因此对C#并不是很了解.

我想创建一个带有约束的定制泛型向量类，即类型参数必须实现接口INumber(Of T).然而，当我试图在所述类中声明+-operator(使用由两个向量给出的值的元素相加)时，我的VB.NET项目产生了以下错误:

错误BC30452没有为类型‘T’和‘T’定义运算符‘+’

因为我几乎只测试了this page上给出的例子，并不真的相信微软会发布一些不起作用的东西，所以我决定也用C#(也使用.NET7)来测试我的问题.

为此，我在VB.NET年内建立了两个MWE

Vector.vb:

Imports System.Numerics


Public Class Vector(Of T As INumber(Of T))

    Private _items() As T

    Public Sub New(n As Integer)
        ReDim _items(n - 1)
    End Sub

    Public ReadOnly Property Size As Integer
        Get
            Return _items.Length
        End Get
    End Property

    Public Function GetValue(i As Integer) As T
        Return _items(i)
    End Function

    Public Sub SetValue(i As Integer, val As T)
        _items(i) = val
    End Sub

    Public Sub SetAll(val As T)
        For i As Integer = 0 To _items.Length - 1
            _items(i) = val
        Next
    End Sub

    Public Sub Print()
        For i As Integer = 0 To _items.Length - 1
            Console.WriteLine(_items(i))
        Next
    End Sub

    Public Shared Operator +(a As Vector(Of T), b As Vector(Of T)) As Vector(Of T)
        Dim retVal As New Vector(Of T)(a.Size)
        For i As Integer = 0 To retVal.Size - 1
            retVal.SetValue(i, a.GetValue(i) + b.GetValue(i))
        Next
        Return retVal
    End Operator

End Class

Program.vb:

Module Program
    Sub Main(args As String())
        Dim x As New Vector(Of Double)(3)
        x.SetAll(3)
        Dim y As New Vector(Of Double)(3)
        y.SetAll(2)
        Dim z = x + y
        z.Print()
    End Sub
End Module

在C#年内

Vector.cs:

using System.Numerics;


namespace Test
{
    public class Vector<T> where T : INumber<T>
    {
        private T[] _items;

        public Vector(int n) {
            Array.Resize<T>(ref _items, n);
        }
        public int Size {
            get { return _items.Length; }
        }
        public T GetValue(int i) {
            return _items[i];
        }
        public void SetValue(int i, T val){
            _items[i] = val;
        }
        public void SetAll(T val) {
            for (var i = 0; i < _items.Length; i++) {
                _items[i] = val;
            }
        }
        public void Print() {
            for (var i = 0; i < _items.Length; i++) {
                Console.WriteLine(_items[i]);
            }
        }
        public static Vector<T> operator +(Vector<T> a, Vector<T> b)
        {
            var retVal = new Vector<T>(a.Size);
            for (var i = 0; i < retVal.Size; i++) {
                retVal.SetValue(i, a.GetValue(i) + b.GetValue(i));
            }
            return retVal;
        }
    }
}

Program.cs:

using Test;


var x = new Vector<Double>(3);
x.SetAll(3);
var y = new Vector<Double>(3);
y.SetAll(2);
var z = x + y;
z.Print();

在每个MWE中，创建长度为3的两个向量(双倍)x，y，使得x的所有条目都是3，y的所有条目都是2.然后将这些向量相加并保存在向量z中.

C#项目编译时没有出现错误，并生成以下输出

5
5
5

while the VB.NET project won't compile and throws above mentioned error.

I don't even really understand why the error is thrown in the first place. The type parameter was given the constrain, that it has to implement the interface INumber(Of T), which in return implements the IAdditionOperators(Of T,T,T) interface, which in return exposes the +-operator. I therefore thought, that T should be able to rely on said operator, like it does in C#, but not in VB.NET.

Is that an error on my site or is VB.NET not working correctly in that regard?