fix: make PH2153 fixer less aggressive for standalone statements

Agent-Logs-Url: https://github.com/philips-software/roslyn-analyzers/sessions/438a660c-8a91-4654-b7e0-aab21311773f

Co-authored-by: bcollamore <57269455+bcollamore@users.noreply.github.com>

Author: Copilot

Philips.CodeAnalysis.MaintainabilityAnalyzers/Maintainability/AvoidUnusedToStringCodeFixProvider.cs

@@ -28,19 +28,41 @@ protected override async Task<Document> ApplyFix(Document document, InvocationEx
 				return document;
 			}
 
-			// Case 1: Standalone expression statement (expr.ToString();) - remove the entire statement
+			ExpressionSyntax receiver = memberAccess.Expression;
+
+			// Case 1: Standalone expression statement (expr.ToString();)
 			if (node.Parent is ExpressionStatementSyntax expressionStatement)
 			{
-				rootNode = rootNode.RemoveNode(expressionStatement, SyntaxRemoveOptions.KeepDirectives);
+				// Only remove the entire statement when the receiver is known to be side-effect free:
+				// local variable, parameter, or 'this'.
+				if (IsSideEffectFree(receiver))
+				{
+					rootNode = rootNode.RemoveNode(expressionStatement, SyntaxRemoveOptions.KeepDirectives);
+				}
+				else
+				{
+					// Keep the receiver expression as a standalone statement to preserve side effects.
+					ExpressionStatementSyntax newStatement = expressionStatement
+						.WithExpression(receiver.WithoutTrivia())
+						.WithLeadingTrivia(expressionStatement.GetLeadingTrivia())
+						.WithTrailingTrivia(expressionStatement.GetTrailingTrivia())
+						.WithAdditionalAnnotations(Formatter.Annotation);
+					rootNode = rootNode.ReplaceNode(expressionStatement, newStatement);
+				}
+
 				return document.WithSyntaxRoot(rootNode);
 			}
 
 			// Case 2: Assignment to discard (_ = expr.ToString()) - replace with just the expression
-			ExpressionSyntax expression = memberAccess.Expression;
 			SyntaxTriviaList trivia = node.GetLeadingTrivia();
-			ExpressionSyntax newExpression = expression.WithLeadingTrivia(trivia).WithAdditionalAnnotations(Formatter.Annotation);
+			ExpressionSyntax newExpression = receiver.WithLeadingTrivia(trivia).WithAdditionalAnnotations(Formatter.Annotation);
 			rootNode = rootNode.ReplaceNode(node, newExpression);
 			return document.WithSyntaxRoot(rootNode);
 		}
+
+		private static bool IsSideEffectFree(ExpressionSyntax expression)
+		{
+			return expression is IdentifierNameSyntax or ThisExpressionSyntax;
+		}
 	}
 }

Philips.CodeAnalysis.Test/Maintainability/Maintainability/AvoidUnusedToStringAnalyzerTest.cs

@@ -182,7 +182,59 @@ private void SomeMethod(string value) { }
 
 		[TestMethod]
 		[TestCategory(TestDefinitions.UnitTests)]
-		public async Task FixStandaloneToStringRemovesEntireStatement()
+		public async Task FixStandaloneLocalVariableToStringRemovesEntireStatement()
+		{
+			var test = @"
+class TestClass
+{
+	public void TestMethod()
+	{
+		var node = ""test"";
+		node.ToString();
+	}
+}";
+
+			var fixedCode = @"
+class TestClass
+{
+	public void TestMethod()
+	{
+		var node = ""test"";
+	}
+}";
+
+			await VerifyDiagnostic(test).ConfigureAwait(false);
+			await VerifyFix(test, fixedCode, shouldAllowNewCompilerDiagnostics: true).ConfigureAwait(false);
+		}
+
+		[TestMethod]
+		[TestCategory(TestDefinitions.UnitTests)]
+		public async Task FixStandaloneThisToStringRemovesEntireStatement()
+		{
+			var test = @"
+class TestClass
+{
+	public void TestMethod()
+	{
+		this.ToString();
+	}
+}";
+
+			var fixedCode = @"
+class TestClass
+{
+	public void TestMethod()
+	{
+	}
+}";
+
+			await VerifyDiagnostic(test).ConfigureAwait(false);
+			await VerifyFix(test, fixedCode).ConfigureAwait(false);
+		}
+
+		[TestMethod]
+		[TestCategory(TestDefinitions.UnitTests)]
+		public async Task FixStandaloneMethodCallToStringKeepsMethodCall()
 		{
 			var test = @"
 class TestClass
@@ -200,6 +252,7 @@ class TestClass
 	public string GetNode() => ""test"";
 	public void TestMethod()
 	{
+		GetNode();
 	}
 }";