Nullable: System.Runtime.CompilerServices (dotnet#23886)

stephentoub · web-flow · commit a65921cc086c · 2019-04-12T10:04:45.000-04:00
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncIteratorMethodBuilder.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncIteratorMethodBuilder.cs
@@ -2,9 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Runtime.InteropServices;
 using System.Threading;
-using System.Threading.Tasks;
 
 namespace System.Runtime.CompilerServices
 {
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncIteratorStateMachineAttribute.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncIteratorStateMachineAttribute.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     /// <summary>Indicates whether a method is an asynchronous iterator.</summary>
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncMethodBuilder.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncMethodBuilder.cs
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncStateMachineAttribute.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncStateMachineAttribute.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     [AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncValueTaskMethodBuilder.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/AsyncValueTaskMethodBuilder.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Runtime.InteropServices;
 using System.Security;
 using System.Threading.Tasks;
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/CompilationRelaxations.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/CompilationRelaxations.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     /// IMPORTANT: Keep this in sync with corhdr.h
@@ -12,4 +13,4 @@ public enum CompilationRelaxations : int
                                     // so we'll start here just in case somebody used them. This flag is only
                                     // valid when set for Assemblies.
     }
-}
+}
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ConfiguredAsyncDisposable.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ConfiguredAsyncDisposable.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Runtime.InteropServices;
 
 namespace System.Runtime.CompilerServices
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ConfiguredCancelableAsyncEnumerable.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ConfiguredCancelableAsyncEnumerable.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Collections.Generic;
 using System.Runtime.InteropServices;
 using System.Threading;
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ConfiguredValueTaskAwaitable.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ConfiguredValueTaskAwaitable.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Threading;
@@ -57,7 +58,7 @@ public bool IsCompleted
             /// <summary>Schedules the continuation action for the <see cref="ConfiguredValueTaskAwaitable"/>.</summary>
             public void OnCompleted(Action continuation)
             {
-                object obj = _value._obj;
+                object? obj = _value._obj;
                 Debug.Assert(obj == null || obj is Task || obj is IValueTaskSource);
 
                 if (obj is Task t)
@@ -79,7 +80,7 @@ public void OnCompleted(Action continuation)
             /// <summary>Schedules the continuation action for the <see cref="ConfiguredValueTaskAwaitable"/>.</summary>
             public void UnsafeOnCompleted(Action continuation)
             {
-                object obj = _value._obj;
+                object? obj = _value._obj;
                 Debug.Assert(obj == null || obj is Task || obj is IValueTaskSource);
 
                 if (obj is Task t)
@@ -99,7 +100,7 @@ public void UnsafeOnCompleted(Action continuation)
 
             void IStateMachineBoxAwareAwaiter.AwaitUnsafeOnCompleted(IAsyncStateMachineBox box)
             {
-                object obj = _value._obj;
+                object? obj = _value._obj;
                 Debug.Assert(obj == null || obj is Task || obj is IValueTaskSource);
 
                 if (obj is Task t)
@@ -163,7 +164,7 @@ public bool IsCompleted
             /// <summary>Schedules the continuation action for the <see cref="ConfiguredValueTaskAwaitable{TResult}"/>.</summary>
             public void OnCompleted(Action continuation)
             {
-                object obj = _value._obj;
+                object? obj = _value._obj;
                 Debug.Assert(obj == null || obj is Task<TResult> || obj is IValueTaskSource<TResult>);
 
                 if (obj is Task<TResult> t)
@@ -185,7 +186,7 @@ public void OnCompleted(Action continuation)
             /// <summary>Schedules the continuation action for the <see cref="ConfiguredValueTaskAwaitable{TResult}"/>.</summary>
             public void UnsafeOnCompleted(Action continuation)
             {
-                object obj = _value._obj;
+                object? obj = _value._obj;
                 Debug.Assert(obj == null || obj is Task<TResult> || obj is IValueTaskSource<TResult>);
 
                 if (obj is Task<TResult> t)
@@ -205,7 +206,7 @@ public void UnsafeOnCompleted(Action continuation)
 
             void IStateMachineBoxAwareAwaiter.AwaitUnsafeOnCompleted(IAsyncStateMachineBox box)
             {
-                object obj = _value._obj;
+                object? obj = _value._obj;
                 Debug.Assert(obj == null || obj is Task<TResult> || obj is IValueTaskSource<TResult>);
 
                 if (obj is Task<TResult> t)
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ContractHelper.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ContractHelper.cs
@@ -4,7 +4,7 @@
 
 #define DEBUG // The behavior of this contract library should be consistent regardless of build type.
 
-using System.Diagnostics;
+#nullable enable
 using System.Diagnostics.Contracts;
 
 namespace System.Runtime.CompilerServices
@@ -31,14 +31,14 @@ public static class ContractHelper
         ///          Otherwise, returns the localized failure message.
         /// </summary>
         [System.Diagnostics.DebuggerNonUserCode]
-        public static string RaiseContractFailedEvent(ContractFailureKind failureKind, string userMessage, string conditionText, Exception innerException)
+        public static string? RaiseContractFailedEvent(ContractFailureKind failureKind, string? userMessage, string? conditionText, Exception? innerException)
         {
             if (failureKind < ContractFailureKind.Precondition || failureKind > ContractFailureKind.Assume)
                 throw new ArgumentException(SR.Format(SR.Arg_EnumIllegalVal, failureKind), nameof(failureKind));
 
-            string returnValue;
+            string? returnValue;
             string displayMessage = "contract failed.";  // Incomplete, but in case of OOM during resource lookup...
-            ContractFailedEventArgs eventArgs = null;  // In case of OOM.
+            ContractFailedEventArgs? eventArgs = null;  // In case of OOM.
 
             try
             {
@@ -78,14 +78,15 @@ public static string RaiseContractFailedEvent(ContractFailureKind failureKind, s
                     returnValue = displayMessage;
                 }
             }
+
             return returnValue;
         }
 
         /// <summary>
         /// Rewriter calls this method to get the default failure behavior.
         /// </summary>
         [System.Diagnostics.DebuggerNonUserCode]
-        public static void TriggerFailure(ContractFailureKind kind, string displayMessage, string userMessage, string conditionText, Exception innerException)
+        public static void TriggerFailure(ContractFailureKind kind, string? displayMessage, string? userMessage, string? conditionText, Exception? innerException)
         {
             if (string.IsNullOrEmpty(displayMessage))
             {
@@ -95,7 +96,7 @@ public static void TriggerFailure(ContractFailureKind kind, string displayMessag
             System.Diagnostics.Debug.ContractFailure(displayMessage, string.Empty, GetFailureMessage(kind, null));
         }
 
-        private static string GetFailureMessage(ContractFailureKind failureKind, string conditionText)
+        private static string GetFailureMessage(ContractFailureKind failureKind, string? conditionText)
         {
             bool hasConditionText = !string.IsNullOrEmpty(conditionText);
             switch (failureKind)
@@ -124,7 +125,7 @@ private static string GetFailureMessage(ContractFailureKind failureKind, string
             }
         }
 
-        private static string GetDisplayMessage(ContractFailureKind failureKind, string userMessage, string conditionText)
+        private static string GetDisplayMessage(ContractFailureKind failureKind, string? userMessage, string? conditionText)
         {
             string failureMessage;
             // Well-formatted English messages will take one of four forms.  A sentence ending in
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/DateTimeConstantAttribute.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/DateTimeConstantAttribute.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter, Inherited = false)]
@@ -14,6 +15,6 @@ public DateTimeConstantAttribute(long ticks)
             _date = new DateTime(ticks);
         }
 
-        public override object Value => _date;
+        public override object? Value => _date; // TODO-NULLABLE: https://github.com/dotnet/roslyn/issues/23268
     }
 }
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/IAsyncStateMachine.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/IAsyncStateMachine.cs
@@ -10,6 +10,7 @@
 //
 // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     /// <summary>
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ICastable.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ICastable.cs
@@ -2,8 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
-
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     /// <summary>
@@ -33,7 +32,7 @@ public interface ICastable
         // because this is the only guard placed before an interface invocation at runtime. If a type decides
         // it no longer wants to implement a given interface it has no way to synchronize with callers that
         // have already cached this relationship and can invoke directly via the interface pointer.
-        bool IsInstanceOfInterface(RuntimeTypeHandle interfaceType, out Exception castError);
+        bool IsInstanceOfInterface(RuntimeTypeHandle interfaceType, out Exception? castError);
 
         // This is called as part of the interface dispatch mechanism when the dispatcher logic cannot find
         // the given interface type in the interface map of this object.
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/INotifyCompletion.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/INotifyCompletion.cs
@@ -9,9 +9,7 @@
 // Interfaces used to represent instances that notify listeners of their completion via continuations.
 // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 
-using System;
-using System.Security;
-
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     /// <summary>
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ITuple.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ITuple.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     /// <summary>
@@ -17,6 +18,6 @@ public interface ITuple
         /// <summary>
         /// Get the element at position <param name="index"/>.
         /// </summary>
-        object this[int index] { get; }
+        object? this[int index] { get; }
     }
 }
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/IsConst.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/IsConst.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     public static partial class IsConst
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/IsVolatile.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/IsVolatile.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     public static class IsVolatile
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/IteratorStateMachineAttribute.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/IteratorStateMachineAttribute.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     [AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/LoadHint.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/LoadHint.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     public enum LoadHint
@@ -10,4 +11,4 @@ public enum LoadHint
         Always = 0x0001,            // Dependency is always loaded
         Sometimes = 0x0002,         // Dependency is sometimes loaded
     }
-}
+}
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/MethodCodeType.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/MethodCodeType.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 using System.Reflection;
 
 namespace System.Runtime.CompilerServices
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/MethodImplOptions.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/MethodImplOptions.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     // This Enum matchs the miImpl flags defined in corhdr.h. It is used to specify 
@@ -19,4 +20,4 @@ public enum MethodImplOptions
         AggressiveOptimization = 0x0200,
         InternalCall = 0x1000
     }
-}
+}
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/RuntimeFeature.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/RuntimeFeature.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     public static partial class RuntimeFeature
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/StrongBox.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/StrongBox.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
 namespace System.Runtime.CompilerServices
 {
     /// <summary>
@@ -15,7 +16,7 @@ public class StrongBox<T> : IStrongBox
         /// <remarks>This is explicitly exposed as a field instead of a property to enable loading the address of the field.</remarks>
         /// </summary>
         [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1051:DoNotDeclareVisibleInstanceFields")]
-        public T Value;
+        public T Value = default!; // TODO-NULLABLE-GENERIC
 
         /// <summary>
         /// Initializes a new StrongBox which can receive a value when used in a reference call.
@@ -33,15 +34,15 @@ public StrongBox(T value)
             Value = value;
         }
 
-        object IStrongBox.Value
+        object? IStrongBox.Value
         {
             get
             {
                 return Value;
             }
             set
             {
-                Value = (T)value;
+                Value = (T)value!; // TODO-NULLABLE-GENERIC
             }
         }
     }
@@ -54,6 +55,6 @@ public interface IStrongBox
         /// <summary>
         /// Gets or sets the value the object references.
         /// </summary>
-        object Value { get; set; }
+        object? Value { get; set; }
     }
 }
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/TaskAwaiter.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/TaskAwaiter.cs
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ValueTaskAwaiter.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/ValueTaskAwaiter.cs
diff --git a/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/YieldAwaitable.cs b/src/System.Private.CoreLib/shared/System/Runtime/CompilerServices/YieldAwaitable.cs
diff --git a/src/System.Private.CoreLib/shared/System/Threading/ThreadPool.cs b/src/System.Private.CoreLib/shared/System/Threading/ThreadPool.cs

Original file line number	Diff line number	Diff line change
`@@ -2,9 +2,9 @@`
`2`	`2`	`// The .NET Foundation licenses this file to you under the MIT license.`
`3`	`3`	`// See the LICENSE file in the project root for more information.`
`4`	`4`
	`5`	`+#nullable enable`
`5`	`6`	`using System.Runtime.InteropServices;`
`6`	`7`	`using System.Threading;`
`7`		`-using System.Threading.Tasks;`
`8`	`8`
`9`	`9`	`namespace System.Runtime.CompilerServices`
`10`	`10`	`{`
Original file line number	Diff line number	Diff line change
`@@ -2,6 +2,7 @@`
`2`	`2`	`// The .NET Foundation licenses this file to you under the MIT license.`
`3`	`3`	`// See the LICENSE file in the project root for more information.`
`4`	`4`
	`5`	`+#nullable enable`
`5`	`6`	`namespace System.Runtime.CompilerServices`
`6`	`7`	`{`
`7`	`8`	`/// <summary>Indicates whether a method is an asynchronous iterator.</summary>`
Original file line number	Diff line number	Diff line change
`@@ -4,7 +4,7 @@`
`4`	`4`
`5`	`5`	`#define DEBUG // The behavior of this contract library should be consistent regardless of build type.`
`6`	`6`
`7`		`-using System.Diagnostics;`
	`7`	`+#nullable enable`
`8`	`8`	`using System.Diagnostics.Contracts;`
`9`	`9`
`10`	`10`	`namespace System.Runtime.CompilerServices`
`@@ -31,14 +31,14 @@ public static class ContractHelper`
`31`	`31`	`/// Otherwise, returns the localized failure message.`
`32`	`32`	`/// </summary>`
`33`	`33`	`[System.Diagnostics.DebuggerNonUserCode]`
`34`		`- public static string RaiseContractFailedEvent(ContractFailureKind failureKind, string userMessage, string conditionText, Exception innerException)`
	`34`	`+ public static string? RaiseContractFailedEvent(ContractFailureKind failureKind, string? userMessage, string? conditionText, Exception? innerException)`
`35`	`35`	`{`
`36`	`36`	`if (failureKind < ContractFailureKind.Precondition \|\| failureKind > ContractFailureKind.Assume)`
`37`	`37`	`throw new ArgumentException(SR.Format(SR.Arg_EnumIllegalVal, failureKind), nameof(failureKind));`
`38`	`38`
`39`		`- string returnValue;`
	`39`	`+ string? returnValue;`
`40`	`40`	`string displayMessage = "contract failed."; // Incomplete, but in case of OOM during resource lookup...`
`41`		`- ContractFailedEventArgs eventArgs = null; // In case of OOM.`
	`41`	`+ ContractFailedEventArgs? eventArgs = null; // In case of OOM.`
`42`	`42`
`43`	`43`	`try`
`44`	`44`	`{`
`@@ -78,14 +78,15 @@ public static string RaiseContractFailedEvent(ContractFailureKind failureKind, s`
`78`	`78`	`returnValue = displayMessage;`
`79`	`79`	`}`
`80`	`80`	`}`
	`81`	`+`
`81`	`82`	`return returnValue;`
`82`	`83`	`}`
`83`	`84`
`84`	`85`	`/// <summary>`
`85`	`86`	`/// Rewriter calls this method to get the default failure behavior.`
`86`	`87`	`/// </summary>`
`87`	`88`	`[System.Diagnostics.DebuggerNonUserCode]`
`88`		`- public static void TriggerFailure(ContractFailureKind kind, string displayMessage, string userMessage, string conditionText, Exception innerException)`
	`89`	`+ public static void TriggerFailure(ContractFailureKind kind, string? displayMessage, string? userMessage, string? conditionText, Exception? innerException)`
`89`	`90`	`{`
`90`	`91`	`if (string.IsNullOrEmpty(displayMessage))`
`91`	`92`	`{`
`@@ -95,7 +96,7 @@ public static void TriggerFailure(ContractFailureKind kind, string displayMessag`
`95`	`96`	`System.Diagnostics.Debug.ContractFailure(displayMessage, string.Empty, GetFailureMessage(kind, null));`
`96`	`97`	`}`
`97`	`98`
`98`		`- private static string GetFailureMessage(ContractFailureKind failureKind, string conditionText)`
	`99`	`+ private static string GetFailureMessage(ContractFailureKind failureKind, string? conditionText)`
`99`	`100`	`{`
`100`	`101`	`bool hasConditionText = !string.IsNullOrEmpty(conditionText);`
`101`	`102`	`switch (failureKind)`
`@@ -124,7 +125,7 @@ private static string GetFailureMessage(ContractFailureKind failureKind, string`
`124`	`125`	`}`
`125`	`126`	`}`
`126`	`127`
`127`		`- private static string GetDisplayMessage(ContractFailureKind failureKind, string userMessage, string conditionText)`
	`128`	`+ private static string GetDisplayMessage(ContractFailureKind failureKind, string? userMessage, string? conditionText)`
`128`	`129`	`{`
`129`	`130`	`string failureMessage;`
`130`	`131`	`// Well-formatted English messages will take one of four forms. A sentence ending in`