RSRP-296676: GetEnumerator() methods of many collections lack [Pure] annotation

using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Diagnostics;

class A
{
    static void Foo()
    {
        var x1 = new List<int>();
        x1.GetEnumerator(); // Correct warning

        var x2 = new Stack<int>();
        x2.GetEnumerator();

        var x3 = new Queue<int>();
        x3.GetEnumerator();

        var x4 = new LinkedList<int>();
        x4.GetEnumerator();

        var x6 = new Dictionary<int, int>();
        x6.GetEnumerator();

        var x7 = new StringCollection();
        x7.GetEnumerator();

        var x8 = new NameValueCollection();
        x8.GetEnumerator();

        var x9 = new ArrayList();
        x9.GetEnumerator();

        var x10 = new Stack();
        x10.GetEnumerator();

        var x11 = new ProcessModuleCollection(new ProcessModule[0]);
        x11.GetEnumerator();
    }
}