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diff --git a/src/mscorlib/src/System/Collections/Generic/IEnumerable.cs b/src/mscorlib/src/System/Collections/Generic/IEnumerable.cs
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+++ b/src/mscorlib/src/System/Collections/Generic/IEnumerable.cs
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+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+/*============================================================
+**
+** Interface:  IEnumerable
+** 
+** 
+**
+**
+** Purpose: Interface for providing generic IEnumerators
+**
+** 
+===========================================================*/
+namespace System.Collections.Generic {
+    using System;
+    using System.Collections;
+    using System.Runtime.InteropServices;
+    using System.Runtime.CompilerServices;
+    using System.Diagnostics.Contracts;
+
+    // Implement this interface if you need to support foreach semantics.
+
+    // Note that T[] : IList<T>, and we want to ensure that if you use
+    // IList<YourValueType>, we ensure a YourValueType[] can be used 
+    // without jitting.  Hence the TypeDependencyAttribute on SZArrayHelper.
+    // This is a special workaround internally though - see VM\compile.cpp.
+    // The same attribute is on IList<T> and ICollection<T>.
+    [TypeDependencyAttribute("System.SZArrayHelper")]
+#if CONTRACTS_FULL
+    [ContractClass(typeof(IEnumerableContract<>))]
+#endif // CONTRACTS_FULL
+    public interface IEnumerable<out T> : IEnumerable
+    {
+        // Returns an IEnumerator for this enumerable Object.  The enumerator provides
+        // a simple way to access all the contents of a collection.
+        /// <include file='doc\IEnumerable.uex' path='docs/doc[@for="IEnumerable.GetEnumerator"]/*' />
+        new IEnumerator<T> GetEnumerator();
+    }
+
+#if CONTRACTS_FULL
+    [ContractClassFor(typeof(IEnumerable<>))]
+    internal abstract class IEnumerableContract<T> : IEnumerable<T>
+    {
+        [Pure]
+        IEnumerator<T> IEnumerable<T>.GetEnumerator()
+        {
+            Contract.Ensures(Contract.Result<IEnumerator<T>>() != null);
+            return default(IEnumerator<T>);
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return default(IEnumerator);
+        }
+    }
+#endif // CONTRACTS_FULL
+}