Make NotificationOption2 a serializable struct

src/Workspaces/Core/Portable/CodeStyle/CodeStyleOption.cs

@@ -25,7 +25,7 @@ internal CodeStyleOption(CodeStyleOption2<T> codeStyleOptionImpl)
             => _codeStyleOptionImpl = codeStyleOptionImpl;
 
         public CodeStyleOption(T value, NotificationOption notification)
-            : this(new CodeStyleOption2<T>(value, (NotificationOption2)notification))
+            : this(new CodeStyleOption2<T>(value, new NotificationOption2(notification.Severity)))
         {
         }
 

src/Workspaces/Core/Portable/CodeStyle/CodeStyleOption2_operators.cs

@@ -16,7 +16,7 @@ internal sealed partial class CodeStyleOption2<T>
                 return null;
             }
 
-            return new CodeStyleOption<T>(option.Value, (NotificationOption?)option.Notification);
+            return new CodeStyleOption<T>(option.Value, (NotificationOption)option.Notification);
         }
 
         [return: NotNullIfNotNull("option")]

src/Workspaces/Core/Portable/CodeStyle/NotificationOption2_operators.cs

@@ -2,41 +2,14 @@
 // 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.Diagnostics.CodeAnalysis;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CodeStyle
 {
-    internal sealed partial class NotificationOption2
+    internal readonly partial record struct NotificationOption2
     {
-        [return: NotNullIfNotNull("notificationOption")]
-        public static explicit operator NotificationOption2?(NotificationOption? notificationOption)
-        {
-            if (notificationOption is null)
-            {
-                return null;
-            }
-
-            return notificationOption.Severity switch
-            {
-                ReportDiagnostic.Suppress => None,
-                ReportDiagnostic.Hidden => Silent,
-                ReportDiagnostic.Info => Suggestion,
-                ReportDiagnostic.Warn => Warning,
-                ReportDiagnostic.Error => Error,
-                _ => throw ExceptionUtilities.UnexpectedValue(notificationOption.Severity),
-            };
-        }
-
-        [return: NotNullIfNotNull("notificationOption")]
-        public static explicit operator NotificationOption?(NotificationOption2? notificationOption)
-        {
-            if (notificationOption is null)
-            {
-                return null;
-            }
-
-            return notificationOption.Severity switch
+        public static explicit operator NotificationOption(NotificationOption2 notificationOption)
+            => notificationOption.Severity switch
             {
                 ReportDiagnostic.Suppress => NotificationOption.None,
                 ReportDiagnostic.Hidden => NotificationOption.Silent,
@@ -45,6 +18,5 @@ internal sealed partial class NotificationOption2
                 ReportDiagnostic.Error => NotificationOption.Error,
                 _ => throw ExceptionUtilities.UnexpectedValue(notificationOption.Severity),
             };
-        }
     }
 }

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/CodeStyle/CodeStyleHelpers.cs

@@ -59,7 +59,7 @@ public static bool TryGetCodeStyleValue(
         /// a NotificationOption, so <paramref name="notification"/> will default to <paramref name="defaultNotification"/>.
         /// </summary>
         public static bool TryGetCodeStyleValueAndOptionalNotification(
-            string arg, NotificationOption2 defaultNotification, [NotNullWhen(true)] out string? value, [NotNullWhen(true)] out NotificationOption2? notification)
+            string arg, NotificationOption2 defaultNotification, [NotNullWhen(true)] out string? value, [NotNullWhen(true)] out NotificationOption2 notification)
         {
             var args = arg.Split(':');
             Debug.Assert(args.Length > 0);
@@ -86,7 +86,7 @@ public static bool TryGetCodeStyleValueAndOptionalNotification(
 
             // We only support 0 or 1 args.  Anything else can't be parsed properly.
             value = null;
-            notification = null;
+            notification = default;
             return false;
         }
 

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/CodeStyle/CodeStyleOption2`1.cs

@@ -53,7 +53,7 @@ static CodeStyleOption2()
         public CodeStyleOption2(T value, NotificationOption2 notification)
         {
             Value = value;
-            _notification = notification ?? throw new ArgumentNullException(nameof(notification));
+            _notification = notification;
         }
 
         public T Value { get; }

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/CodeStyle/CodeStyleOptions2.cs

@@ -309,13 +309,6 @@ private static CodeStyleOption2<AccessibilityModifiersRequired> ParseAccessibili
 
         private static string GetAccessibilityModifiersRequiredEditorConfigString(CodeStyleOption2<AccessibilityModifiersRequired> option, CodeStyleOption2<AccessibilityModifiersRequired> defaultValue)
         {
-            // If they provide 'never', they don't need a notification level.
-            if (option.Notification == null)
-            {
-                Debug.Assert(s_accessibilityModifiersRequiredMap.ContainsValue(AccessibilityModifiersRequired.Never));
-                return s_accessibilityModifiersRequiredMap.GetKeyOrDefault(AccessibilityModifiersRequired.Never)!;
-            }
-
             Debug.Assert(s_accessibilityModifiersRequiredMap.ContainsValue(option.Value));
             return $"{s_accessibilityModifiersRequiredMap.GetKeyOrDefault(option.Value)}{GetEditorConfigStringNotificationPart(option, defaultValue)}";
         }
@@ -425,7 +418,7 @@ private static string GetParenthesesPreferenceEditorConfigString(CodeStyleOption
         {
             Debug.Assert(s_parenthesesPreferenceMap.ContainsValue(option.Value));
             var value = s_parenthesesPreferenceMap.GetKeyOrDefault(option.Value) ?? s_parenthesesPreferenceMap.GetKeyOrDefault(ParenthesesPreference.AlwaysForClarity);
-            return option.Notification == null ? value! : $"{value}{GetEditorConfigStringNotificationPart(option, defaultValue)}";
+            return $"{value}{GetEditorConfigStringNotificationPart(option, defaultValue)}";
         }
 
         private static CodeStyleOption2<UnusedParametersPreference> ParseUnusedParametersPreference(string optionString, CodeStyleOption2<UnusedParametersPreference> defaultValue)
@@ -443,7 +436,7 @@ private static string GetUnusedParametersPreferenceEditorConfigString(CodeStyleO
         {
             Debug.Assert(s_unusedParametersPreferenceMap.ContainsValue(option.Value));
             var value = s_unusedParametersPreferenceMap.GetKeyOrDefault(option.Value) ?? s_unusedParametersPreferenceMap.GetKeyOrDefault(defaultValue.Value);
-            return option.Notification == null ? value! : $"{value}{GetEditorConfigStringNotificationPart(option, defaultValue)}";
+            return $"{value}{GetEditorConfigStringNotificationPart(option, defaultValue)}";
         }
     }
 

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/CodeStyle/NotificationOption2.cs

@@ -2,66 +2,42 @@
 // 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;
-
-#if CODE_STYLE
-using WorkspacesResources = Microsoft.CodeAnalysis.CodeStyleResources;
-#endif
+using System.Runtime.Serialization;
 
 namespace Microsoft.CodeAnalysis.CodeStyle
 {
     /// <summary>
     /// Offers different notification styles for enforcing
     /// a code style. Under the hood, it simply maps to <see cref="DiagnosticSeverity"/>
     /// </summary>
-    /// <remarks>
-    /// This also supports various properties for databinding.
-    /// </remarks>
     /// <completionlist cref="NotificationOption2"/>
-    internal sealed partial class NotificationOption2 : IEquatable<NotificationOption2?>
+    [DataContract]
+    internal readonly partial record struct NotificationOption2(
+        [property: DataMember(Order = 0)] ReportDiagnostic Severity)
     {
         /// <summary>
         /// Notification option to disable or suppress an option with <see cref="ReportDiagnostic.Suppress"/>.
         /// </summary>
-        public static readonly NotificationOption2 None = new(ReportDiagnostic.Suppress);
+        public static NotificationOption2 None => new(ReportDiagnostic.Suppress);
 
         /// <summary>
         /// Notification option for a silent or hidden option with <see cref="ReportDiagnostic.Hidden"/>.
         /// </summary>
-        public static readonly NotificationOption2 Silent = new(ReportDiagnostic.Hidden);
+        public static NotificationOption2 Silent => new(ReportDiagnostic.Hidden);
 
         /// <summary>
         /// Notification option for a suggestion or an info option with <see cref="ReportDiagnostic.Info"/>.
         /// </summary>
-        public static readonly NotificationOption2 Suggestion = new(ReportDiagnostic.Info);
+        public static NotificationOption2 Suggestion => new(ReportDiagnostic.Info);
 
         /// <summary>
         /// Notification option for a warning option with <see cref="ReportDiagnostic.Warn"/>.
         /// </summary>
-        public static readonly NotificationOption2 Warning = new(ReportDiagnostic.Warn);
+        public static NotificationOption2 Warning => new(ReportDiagnostic.Warn);
 
         /// <summary>
         /// Notification option for an error option with <see cref="ReportDiagnostic.Error"/>.
         /// </summary>
-        public static readonly NotificationOption2 Error = new(ReportDiagnostic.Error);
-
-        /// <summary>
-        /// Diagnostic severity associated with notification option.
-        /// </summary>
-        public ReportDiagnostic Severity { get; }
-
-        private NotificationOption2(ReportDiagnostic severity)
-        {
-            Severity = severity;
-        }
-
-        public override bool Equals(object? obj)
-            => obj is NotificationOption2 other && Equals(other);
-
-        public bool Equals(NotificationOption2? other)
-            => other != null && Severity == other.Severity;
-
-        public override int GetHashCode()
-            => Severity.GetHashCode();
+        public static NotificationOption2 Error => new(ReportDiagnostic.Error);
     }
 }