Remove syntax serialization logic.

docs/Breaking API Changes.md

@@ -101,4 +101,12 @@ This could already happen in other load scenarios but this change moves it into
 
 The ability to serialize/deserialize a SyntaxNode to/from a Stream has been deprecated. The code for this still exists in Roslyn, but attempting to call the APIs to perform these functions will result in 'Obsolete' warnings being reported. A future version of Roslyn will remove this functionality entirely. This functionality could only work for a host that wrote out the nodes to a stream, and later read it back in within the same process instance. It could not be used to communicate across processes, or for persisting nodes to disk to be read in at a later time by a new host sessions. This functionality originally existed for the days when Roslyn was hosted in 32bit processes with limited address space. That is no longer a mainline supported scenario. Clients can get similar functionality by persisting the text of the node, and parsing it back out when needed.
 
-PR: https://github.com/dotnet/roslyn/pull/70365
+PR: https://github.com/dotnet/roslyn/pull/70365
+
+# Version 4.9.0
+
+### Obsoletion and removal of SyntaxNode serialization.
+
+Continuation of the deprecation that happened in 4.8.0 (see information above).  In 4.9.0 this functionality is now entirely removed, and will issue both an obsoletion error, and will throw at runtime if the APIs are used.
+
+PR: https://github.com/dotnet/roslyn/pull/70277

src/Analyzers/Core/Analyzers/Helpers/DiagnosticHelper.cs

@@ -276,14 +276,11 @@ public static Diagnostic CreateWithMessage(
             return $"https://learn.microsoft.com/dotnet/fundamentals/code-analysis/style-rules/{id.ToLowerInvariant()}";
         }
 
-        public sealed class LocalizableStringWithArguments : LocalizableString, IObjectWritable
+        public sealed class LocalizableStringWithArguments : LocalizableString
         {
             private readonly LocalizableString _messageFormat;
             private readonly string[] _formatArguments;
 
-            static LocalizableStringWithArguments()
-                => ObjectBinder.RegisterTypeReader(typeof(LocalizableStringWithArguments), reader => new LocalizableStringWithArguments(reader));
-
             public LocalizableStringWithArguments(LocalizableString messageFormat, params object[] formatArguments)
             {
                 if (messageFormat == null)
@@ -304,40 +301,6 @@ public LocalizableStringWithArguments(LocalizableString messageFormat, params ob
                 }
             }
 
-            private LocalizableStringWithArguments(ObjectReader reader)
-            {
-                _messageFormat = (LocalizableString)reader.ReadValue();
-
-                var length = reader.ReadInt32();
-                if (length == 0)
-                {
-                    _formatArguments = Array.Empty<string>();
-                }
-                else
-                {
-                    using var _ = ArrayBuilder<string>.GetInstance(length, out var argumentsBuilder);
-                    for (var i = 0; i < length; i++)
-                    {
-                        argumentsBuilder.Add(reader.ReadString());
-                    }
-
-                    _formatArguments = argumentsBuilder.ToArray();
-                }
-            }
-
-            bool IObjectWritable.ShouldReuseInSerialization => false;
-
-            void IObjectWritable.WriteTo(ObjectWriter writer)
-            {
-                writer.WriteValue(_messageFormat);
-                var length = _formatArguments.Length;
-                writer.WriteInt32(length);
-                for (var i = 0; i < length; i++)
-                {
-                    writer.WriteString(_formatArguments[i]);
-                }
-            }
-
             protected override string GetText(IFormatProvider? formatProvider)
             {
                 var messageFormat = _messageFormat.ToString(formatProvider);

src/Compilers/CSharp/Portable/Errors/MessageProvider.cs

@@ -14,26 +14,14 @@
 
 namespace Microsoft.CodeAnalysis.CSharp
 {
-    internal sealed class MessageProvider : CommonMessageProvider, IObjectWritable
+    internal sealed class MessageProvider : CommonMessageProvider
     {
         public static readonly MessageProvider Instance = new MessageProvider();
 
-        static MessageProvider()
-        {
-            ObjectBinder.RegisterTypeReader(typeof(MessageProvider), r => Instance);
-        }
-
         private MessageProvider()
         {
         }
 
-        bool IObjectWritable.ShouldReuseInSerialization => true;
-
-        void IObjectWritable.WriteTo(ObjectWriter writer)
-        {
-            // write nothing, always read/deserialized as global Instance
-        }
-
         public override DiagnosticSeverity GetSeverity(int code)
         {
             return ErrorFacts.GetSeverity((ErrorCode)code);

src/Compilers/CSharp/Portable/Errors/SyntaxDiagnosticInfo.cs

@@ -10,11 +10,6 @@ namespace Microsoft.CodeAnalysis.CSharp
 {
     internal class SyntaxDiagnosticInfo : DiagnosticInfo
     {
-        static SyntaxDiagnosticInfo()
-        {
-            ObjectBinder.RegisterTypeReader(typeof(SyntaxDiagnosticInfo), r => new SyntaxDiagnosticInfo(r));
-        }
-
         internal readonly int Offset;
         internal readonly int Width;
 
@@ -56,23 +51,5 @@ protected override DiagnosticInfo GetInstanceWithSeverityCore(DiagnosticSeverity
         {
             return new SyntaxDiagnosticInfo(this, severity);
         }
-
-        #region Serialization
-
-        protected override void WriteTo(ObjectWriter writer)
-        {
-            base.WriteTo(writer);
-            writer.WriteInt32(this.Offset);
-            writer.WriteInt32(this.Width);
-        }
-
-        protected SyntaxDiagnosticInfo(ObjectReader reader)
-            : base(reader)
-        {
-            this.Offset = reader.ReadInt32();
-            this.Width = reader.ReadInt32();
-        }
-
-        #endregion
     }
 }

src/Compilers/CSharp/Portable/Errors/XmlSyntaxDiagnosticInfo.cs

@@ -10,11 +10,6 @@ namespace Microsoft.CodeAnalysis.CSharp
 {
     internal sealed class XmlSyntaxDiagnosticInfo : SyntaxDiagnosticInfo
     {
-        static XmlSyntaxDiagnosticInfo()
-        {
-            ObjectBinder.RegisterTypeReader(typeof(XmlSyntaxDiagnosticInfo), r => new XmlSyntaxDiagnosticInfo(r));
-        }
-
         private readonly XmlParseErrorCode _xmlErrorCode;
 
         internal XmlSyntaxDiagnosticInfo(XmlParseErrorCode code, params object[] args)
@@ -38,22 +33,6 @@ protected override DiagnosticInfo GetInstanceWithSeverityCore(DiagnosticSeverity
             return new XmlSyntaxDiagnosticInfo(this, severity);
         }
 
-        #region Serialization
-
-        protected override void WriteTo(ObjectWriter writer)
-        {
-            base.WriteTo(writer);
-            writer.WriteUInt32((uint)_xmlErrorCode);
-        }
-
-        private XmlSyntaxDiagnosticInfo(ObjectReader reader)
-            : base(reader)
-        {
-            _xmlErrorCode = (XmlParseErrorCode)reader.ReadUInt32();
-        }
-
-        #endregion
-
         public override string GetMessage(IFormatProvider? formatProvider = null)
         {
             var culture = formatProvider as CultureInfo;