为什么 ControlCollection 不抛出 InvalidOperationException？

继这个问题用于处理跳过迭代的控件的 Foreach 循环 https://stackoverflow.com/questions/35083873/foreach-loop-for-disposing-controls-skiping-iterations/35084043#35083991让我烦恼的是，允许对不断变化的集合进行迭代：

例如，以下内容：

List<Control> items = new List<Control>
{
    new TextBox {Text = "A", Top = 10},
    new TextBox {Text = "B", Top = 20},
    new TextBox {Text = "C", Top = 30},
    new TextBox {Text = "D", Top = 40},
};

foreach (var item in items)
{
    items.Remove(item);
}

throws

InvalidOperationException：集合已修改；枚举操作可能无法执行。

但是，在 .Net 表单中，您可以执行以下操作：

this.Controls.Add(new TextBox {Text = "A", Top = 10});
this.Controls.Add(new TextBox {Text = "B", Top = 30});
this.Controls.Add(new TextBox {Text = "C", Top = 50});
this.Controls.Add(new TextBox {Text = "D", Top = 70});

foreach (Control control in this.Controls)
{
    control.Dispose();
}

它会跳过元素，因为迭代器在不断变化的集合上运行，不抛出异常

漏洞？迭代器不需要抛出InvalidOperationException如果底层集合发生变化？

所以我的问题是为什么要对变化的迭代ControlCollection不抛出InvalidOperationException？

附录：

The 的文档IEnumerator https://learn.microsoft.com/dotnet/api/system.collections.ienumerator says:

枚举器没有对集合的独占访问权；因此，通过集合进行枚举本质上不是线程安全的过程。即使集合被同步，其他线程仍然可以修改该集合，这会导致枚举器抛出异常.

这个问题的答案可以在参考来源ControlCollectionEnumerator http://referencesource.microsoft.com/#System.Windows.Forms/winforms/Managed/System/WinForms/Control.cs,1ac71dc0d6ce7f92

private class ControlCollectionEnumerator : IEnumerator {
    private ControlCollection controls; 
    private int current;
    private int originalCount;

    public ControlCollectionEnumerator(ControlCollection controls) {
        this.controls = controls;
        this.originalCount = controls.Count;
        current = -1;
    }

    public bool MoveNext() {
        // VSWhidbey 448276
        // We have to use Controls.Count here because someone could have deleted 
        // an item from the array. 
        //
        // this can happen if someone does:
        //     foreach (Control c in Controls) { c.Dispose(); }
        // 
        // We also dont want to iterate past the original size of the collection
        //
        // this can happen if someone does
        //     foreach (Control c in Controls) { c.Controls.Add(new Label()); }

        if (current < controls.Count - 1 && current < originalCount - 1) {
            current++;
            return true;
        }
        else {
            return false;
        }
    }

    public void Reset() {
        current = -1;
    }

    public object Current {
        get {
            if (current == -1) {
                return null;
            }
            else {
                return controls[current];
            }
        }
    }
}

特别注意中的评论MoveNext()其中明确解决了这个问题。

在我看来，这是一个误导性的“修复”，因为它通过引入一个微妙的错误来掩盖一个明显的错误（元素被悄悄地跳过，正如OP所指出的）。