System.Runtime.Intrinsics

 namespace System.Runtime.Intrinsics {
-    public readonly struct Vector128<T> where T : struct {
+    public readonly struct Vector128<T> : IEquatable<Vector128<T>>, IFormattable where T : struct {
+        public static int Count { get; }
+        public override bool Equals(object obj);
+        public bool Equals(Vector128<T> other);
+        public override int GetHashCode();
+        public override string ToString();
+        public string ToString(string format);
+        public string ToString(string format, IFormatProvider formatProvider);
     }
-    public readonly struct Vector256<T> where T : struct {
+    public readonly struct Vector256<T> : IEquatable<Vector256<T>>, IFormattable where T : struct {
+        public static int Count { get; }
+        public override bool Equals(object obj);
+        public bool Equals(Vector256<T> other);
+        public override int GetHashCode();
+        public override string ToString();
+        public string ToString(string format);
+        public string ToString(string format, IFormatProvider formatProvider);
     }
-    public readonly struct Vector64<T> where T : struct {
+    public readonly struct Vector64<T> : IEquatable<Vector64<T>>, IFormattable where T : struct {
+        public static int Count { get; }
+        public override bool Equals(object obj);
+        public bool Equals(Vector64<T> other);
+        public override int GetHashCode();
+        public override string ToString();
+        public string ToString(string format);
+        public string ToString(string format, IFormatProvider formatProvider);
     }
 }