Block ENC for extension blocks

src/Features/CSharp/Portable/CSharpFeaturesResources.resx

@@ -587,4 +587,4 @@
   <data name="Convert_all_extension_methods_in_0_to_extension" xml:space="preserve">
     <value>Convert all extension methods in '{0}' to extension</value>
   </data>
-</root>
+</root>

src/Features/CSharp/Portable/EditAndContinue/CSharpEditAndContinueAnalyzer.cs

@@ -929,7 +929,7 @@ internal override bool IsDeclarationWithInitializer(SyntaxNode declaration)
     }
 
     internal override bool IsPrimaryConstructorDeclaration(SyntaxNode declaration)
-        => declaration.Parent is TypeDeclarationSyntax { ParameterList: var parameterList } && parameterList == declaration;
+        => declaration.Parent is TypeDeclarationSyntax { ParameterList: var parameterList } and not ExtensionBlockDeclarationSyntax && parameterList == declaration;
 
     internal override bool IsConstructorWithMemberInitializers(ISymbol symbol, CancellationToken cancellationToken)
     {
@@ -1643,6 +1643,10 @@ private static bool GroupBySignatureEquivalent(IMethodSymbol? oldMethod, IMethod
                 return GetDiagnosticSpan(typeDeclaration.Modifiers, typeDeclaration.Keyword,
                     typeDeclaration.TypeParameterList ?? (SyntaxNodeOrToken)typeDeclaration.Identifier);
 
+            case SyntaxKind.ExtensionBlockDeclaration:
+                var extensionBlockDeclaration = (ExtensionBlockDeclarationSyntax)node;
+                return extensionBlockDeclaration.Keyword.Span;
+
             case SyntaxKind.BaseList:
                 var baseList = (BaseListSyntax)node;
                 return baseList.Types.Span;
@@ -2248,6 +2252,9 @@ internal override string GetDisplayName(IMethodSymbol symbol)
 
                 return CSharpFeaturesResources.local_variable_declaration;
 
+            case SyntaxKind.ExtensionBlockDeclaration:
+                return FeaturesResources.extension_block;
+
             default:
                 return null;
         }
@@ -2395,6 +2402,11 @@ private void ClassifyInsert(SyntaxNode node)
         {
             switch (node.Kind())
             {
+                case SyntaxKind.ExtensionBlockDeclaration:
+                    // https://github.com/dotnet/roslyn/issues/78959 Disallowed for now
+                    ReportError(RudeEditKind.Insert);
+                    return;
+
                 case SyntaxKind.ExternAliasDirective:
                     ReportError(RudeEditKind.Insert);
                     return;
@@ -2425,6 +2437,11 @@ private void ClassifyDelete(SyntaxNode oldNode)
                     ReportError(RudeEditKind.Delete);
                     return;
 
+                case SyntaxKind.ExtensionBlockDeclaration:
+                    // https://github.com/dotnet/roslyn/issues/78959 Disallowed for now
+                    ReportError(RudeEditKind.Delete);
+                    return;
+
                 case SyntaxKind.AttributeList:
                 case SyntaxKind.Attribute:
                     // To allow removal of attributes we need to check if the removed attribute

src/Features/CSharp/Portable/EditAndContinue/SyntaxComparer.cs

@@ -59,6 +59,7 @@ internal enum Label
 
         TypeDeclaration,
         EnumDeclaration,
+        ExtensionBlockDeclaration,         // tied to parent
         BaseList,                          // tied to parent
         PrimaryConstructorBase,            // tied to parent
         DelegateDeclaration,
@@ -195,6 +196,7 @@ private static int TiedToAncestor(Label label)
             case Label.Parameter:
             case Label.AttributeList:
             case Label.Attribute:
+            case Label.ExtensionBlockDeclaration:
                 return 1;
 
             // Statement syntax
@@ -681,6 +683,9 @@ private static Label ClassifyTopSyntax(SyntaxKind kind, SyntaxNode? node, out bo
                 }
 
                 break;
+
+            case SyntaxKind.ExtensionBlockDeclaration:
+                return Label.ExtensionBlockDeclaration;
         }
 
         // If we got this far, its an unlabelled node. For top
@@ -917,6 +922,10 @@ protected override bool TryComputeWeightedDistance(SyntaxNode leftNode, SyntaxNo
                 distance = ComputeDistance((AttributeSyntax)leftNode, (AttributeSyntax)rightNode);
                 return true;
 
+            case SyntaxKind.ExtensionBlockDeclaration:
+                distance = ComputeDistance((ExtensionBlockDeclarationSyntax)leftNode, (ExtensionBlockDeclarationSyntax)rightNode);
+                return true;
+
             default:
                 var leftName = TryGetName(leftNode);
                 var rightName = TryGetName(rightNode);
@@ -1435,6 +1444,9 @@ private static double CombineOptional(
             case SyntaxKind.DelegateDeclaration:
                 return ((DelegateDeclarationSyntax)node).Identifier;
 
+            case SyntaxKind.ExtensionBlockDeclaration:
+                return null;
+
             case SyntaxKind.FieldDeclaration:
             case SyntaxKind.EventFieldDeclaration:
             case SyntaxKind.VariableDeclaration:

src/Features/CSharp/Portable/EditAndContinue/SyntaxUtilities.cs

@@ -56,7 +56,7 @@ CompilationUnitSyntax unit when unit.ContainsGlobalStatements()
                 when !fieldDeclaration.Modifiers.Any(SyntaxKind.ConstKeyword)
                 => new FieldWithInitializerDeclarationBody(variableDeclarator),
 
-            ParameterListSyntax { Parent: TypeDeclarationSyntax typeDeclaration }
+            ParameterListSyntax { Parent: TypeDeclarationSyntax typeDeclaration and not ExtensionBlockDeclarationSyntax }
                 => typeDeclaration is { BaseList.Types: [PrimaryConstructorBaseTypeSyntax { }, ..] }
                     ? new PrimaryConstructorWithExplicitInitializerDeclarationBody(typeDeclaration)
                     : new PrimaryConstructorWithImplicitInitializerDeclarationBody(typeDeclaration),

src/Features/CSharpTest/EditAndContinue/Helpers/EditingTestBase.cs

@@ -105,6 +105,7 @@ public static string GetResource(string keyword)
             "top-level statement" => CSharpFeaturesResources.top_level_statement,
             "top-level code" => CSharpFeaturesResources.top_level_code,
             "class with explicit or sequential layout" => string.Format(FeaturesResources.class_with_explicit_or_sequential_layout),
+            "extension block" => FeaturesResources.extension_block,
             _ => null
         };