Fix #1247: Empty destructors are not decompiled correctly

ICSharpCode.Decompiler/CSharp/Transforms/PatternStatementTransform.cs

@@ -122,6 +122,11 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			return TransformDestructor(methodDeclaration) ?? base.VisitMethodDeclaration(methodDeclaration);
 		}
 
+		public override AstNode VisitDestructorDeclaration(DestructorDeclaration destructorDeclaration)
+		{
+			return TransformDestructorBody(destructorDeclaration) ?? base.VisitDestructorDeclaration(destructorDeclaration);
+		}
+
 		public override AstNode VisitTryCatchStatement(TryCatchStatement tryCatchStatement)
 		{
 			return TransformTryCatchFinally(tryCatchStatement) ?? base.VisitTryCatchStatement(tryCatchStatement);
@@ -812,12 +817,14 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			Modifiers = Modifiers.Any,
 			ReturnType = new PrimitiveType("void"),
 			Name = "Finalize",
-			Body = new BlockStatement {
-				new TryCatchStatement {
-					TryBlock = new AnyNode("body"),
-					FinallyBlock = new BlockStatement {
-						new InvocationExpression(new MemberReferenceExpression(new BaseReferenceExpression(), "Finalize"))
-					}
+			Body = destructorBodyPattern
+		};
+
+		static readonly BlockStatement destructorBodyPattern = new BlockStatement {
+			new TryCatchStatement {
+				TryBlock = new AnyNode("body"),
+				FinallyBlock = new BlockStatement {
+					new InvocationExpression(new MemberReferenceExpression(new BaseReferenceExpression(), "Finalize"))
 				}
 			}
 		};
@@ -837,6 +844,16 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			}
 			return null;
 		}
+
+		DestructorDeclaration TransformDestructorBody(DestructorDeclaration dtorDef)
+		{
+			Match m = destructorBodyPattern.Match(dtorDef.Body);
+			if (m.Success) {
+				dtorDef.Body = m.Get<BlockStatement>("body").Single().Detach();
+				return dtorDef;
+			}
+			return null;
+		}
 		#endregion
 
 		#region Try-Catch-Finally

ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataMethod.cs

@@ -72,7 +72,7 @@ namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 					this.symbolKind = SymbolKind.Operator;
 			} else if ((attributes & finalizerAttributes) == finalizerAttributes) {
 				string name = this.Name;
-				if (name == "Finalize") {
+				if (name == "Finalize" && Parameters.Count == 0) {
 					this.symbolKind = SymbolKind.Destructor;
 				}
 			}