Remove redundant AnonymousMethodExpression.HasParameterList

The decompiler never emits "delegate () {}" (an explicit empty parameter
list) -- it produces "delegate {}" when there are no parameters and
"delegate (...) {}" when there are -- so HasParameterList always equalled
Parameters.Any(). Drop the property, its backing field and the two setter
calls, and read Parameters.Any() directly at the printer and the
resolve-result builder.

Assisted-by: Claude:claude-opus-4-8:Claude Code

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -2428,7 +2428,6 @@ namespace ICSharpCode.Decompiler.CSharp
 			AnonymousMethodExpression ame = new AnonymousMethodExpression();
 			ame.IsAsync = function.IsAsync;
 			ame.Parameters.AddRange(MakeParameters(function.Parameters, function));
-			ame.HasParameterList = ame.Parameters.Count > 0;
 			var builder = new StatementBuilder(
 				typeSystem,
 				this.decompilationContext,
@@ -2493,7 +2492,6 @@ namespace ICSharpCode.Decompiler.CSharp
 			if (!isLambda && !parameterReferencingIdentifiers.Any())
 			{
 				ame.Parameters.Clear();
-				ame.HasParameterList = false;
 			}
 
 			Expression replacement;
@@ -2530,7 +2528,7 @@ namespace ICSharpCode.Decompiler.CSharp
 
 			var rr = new DecompiledLambdaResolveResult(
 				function, delegateType, inferredReturnType,
-				hasParameterList: isLambda || ame.HasParameterList,
+				hasParameterList: isLambda || ame.Parameters.Any(),
 				isAnonymousMethod: !isLambda,
 				isImplicitlyTyped: ame.Parameters.Any(p => p.Type is null));
 

ICSharpCode.Decompiler/CSharp/OutputVisitor/CSharpOutputVisitor.cs

@@ -561,7 +561,8 @@ namespace ICSharpCode.Decompiler.CSharp.OutputVisitor
 				Space();
 			}
 			WriteKeyword(AnonymousMethodExpression.DelegateKeyword);
-			if (anonymousMethodExpression.HasParameterList)
+			// No parameters -> "delegate {}" (omit the list); with parameters -> "delegate (...) {}".
+			if (anonymousMethodExpression.Parameters.Any())
 			{
 				Space(policy.SpaceBeforeAnonymousMethodParentheses);
 				WriteCommaSeparatedListInParenthesis(anonymousMethodExpression.Parameters, policy.SpaceWithinAnonymousMethodParentheses);

ICSharpCode.Decompiler/CSharp/Syntax/Expressions/AnonymousMethodExpression.cs

@@ -41,14 +41,6 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 
 		public bool IsAsync { get; set; }
 
-		// used to tell the difference between delegate {} and delegate () {}
-		bool hasParameterList;
-
-		public bool HasParameterList {
-			get { return hasParameterList || Parameters.Any(); }
-			set { hasParameterList = value; }
-		}
-
 		[Slot("Roles.Parameter")]
 		public partial AstNodeCollection<ParameterDeclaration> Parameters { get; }