Use LangVersion:11 and omit AppendFormatted feature only for Unity

sandbox/ConsoleApp/ReadMeSample.cs

@@ -32,7 +32,7 @@ void Sample(int id, string name)
         // like StringBuilder
         var writer = Utf8String.CreateWriter(bufferWriter);
         writer.Append("My Name...");
-        // writer.AppendFormat($"is...? {name}");
+        writer.AppendFormat($"is...? {name}");
         writer.AppendLine();
         writer.Flush();
 
@@ -115,7 +115,7 @@ void WriterSample()
 
         // call each append methods.
         writer.Append("foo");
-        // writer.AppendFormat($"bar {Guid.NewGuid()}");
+        writer.AppendFormat($"bar {Guid.NewGuid()}");
 
         // finally call Flush(or Dispose)
         writer.Flush();
@@ -131,7 +131,7 @@ void WriterSample2(IBufferWriter<byte> otherBufferWriter)
 
         // call each append methods.
         writer.Append("foo");
-        // writer.AppendFormat($"bar {Guid.NewGuid()}");
+        writer.AppendFormat($"bar {Guid.NewGuid()}");
 
         // finally call Flush(or Dispose)
         writer.Flush();

src/Utf8StringInterpolation/Utf8StringInterpolation.csproj

@@ -3,18 +3,14 @@
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;netstandard2.1;net6.0;net8.0</TargetFrameworks>
 		<ImplicitUsings>enable</ImplicitUsings>
-		<LangVersion>10</LangVersion>
+		<LangVersion>11</LangVersion>
 		<Nullable>enable</Nullable>
 		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
 		<NoWarn>$(NoWarn);CS1591;CA2255</NoWarn>
 		<PackageTags>string</PackageTags>
 		<Description>Successor of ZString; UTF8 based zero allocation high-peformance String Interpolation and StringBuilder.</Description>
 	</PropertyGroup>
 
-	<PropertyGroup Condition="'$(TargetFramework)'=='netstandard2.0'">
-		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-	</PropertyGroup>
-
 	<ItemGroup Condition="'$(TargetFramework)'=='netstandard2.0'">
 		<PackageReference Include="System.Memory" Version="4.5.5" />
 	</ItemGroup>

src/Utf8StringInterpolation/Utf8StringWriter.AppendFormatted.cs

@@ -72,7 +72,6 @@ void AppendFormattedAlignment(bool value, int alignment, string? format)
             buffer.Slice(0, bytesWritten).CopyTo(destination);
             destination = destination.Slice(bytesWritten);
             currentWritten += bytesWritten;
-            return;
         }
         else
         {

src/Utf8StringInterpolation/Utf8StringWriter.cs

@@ -89,8 +89,10 @@ public Utf8StringWriter(int literalLength, int formattedCount, Span<byte> destin
         this.bufferWriter.GetSpan(destination.Length); // allocate dummy
     }
 
+#if !UNITY_2022_2_OR_NEWER        
     // from AppendFormat extension methods.
-    public Utf8StringWriter(int literalLength, int formattedCount, ref Utf8StringWriter<TBufferWriter> parent)
+    // This feature required C# 11 or higher, because it needs scoped ref. 
+    public Utf8StringWriter(int literalLength, int formattedCount, scoped ref Utf8StringWriter<TBufferWriter> parent)
     {
         parent.ClearState();
         this.bufferWriter = parent.bufferWriter;
@@ -104,6 +106,7 @@ public Utf8StringWriter(int literalLength, int formattedCount, ref Utf8StringWri
         var initialSize = literalLength + (formattedCount * GuessedLengthPerHole);
         TryGrow(initialSize);
     }
+#endif            
 
     public void AppendLiteral(string s)
     {
@@ -485,24 +488,27 @@ public void Dispose()
     }
 }
 
+// This feature requires C# 11 or newer, because it needs scoped ref.
+#if !UNITY_2022_2_OR_NEWER
 public static class Utf8StringExtensions
 {
     // hack for use nested InterpolatedStringHandler.
 
     public static void AppendFormat<TBufferWriter>(
         this ref Utf8StringWriter<TBufferWriter> parent,
-        [InterpolatedStringHandlerArgument("parent")] ref Utf8StringWriter<TBufferWriter> format)
+        [InterpolatedStringHandlerArgument("parent")] scoped ref Utf8StringWriter<TBufferWriter> format)
         where TBufferWriter : IBufferWriter<byte>
     {
         format.Flush();
     }
 
     public static void AppendLine<TBufferWriter>(
         this ref Utf8StringWriter<TBufferWriter> parent,
-        [InterpolatedStringHandlerArgument("parent")] ref Utf8StringWriter<TBufferWriter> format)
+        [InterpolatedStringHandlerArgument("parent")] scoped ref Utf8StringWriter<TBufferWriter> format)
         where TBufferWriter : IBufferWriter<byte>
     {
         format.Flush();
         parent.AppendLine();
     }
-}
+}
+#endif