Fix PH2144: Handle DiscardDesignationSyntax for out parameters and update documentation severity to Error

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

Author: Copilot

Documentation/Diagnostics/PH2144.md

@@ -1,13 +1,16 @@
 # PH2144: Avoid variables named exactly '_'
 
-| Property                    | Value                                                    |
-|-----------------------------|----------------------------------------------------------|
-| **Rule ID**                 | PH2144                                                   |
-| **Title**                   | Avoid variables named exactly '_'                        |
-| **Category**                | Naming                                                   |
-| **Default severity**        | Warning                                                  |
-
-## Cause
+| Property | Value  |
+|--|--|
+| Package | [Philips.CodeAnalysis.MaintainabilityAnalyzers](https://www.nuget.org/packages/Philips.CodeAnalysis.MaintainabilityAnalyzers) |
+| Diagnostic ID | PH2144 |
+| Category  | [Naming](../Naming.md) |
+| Analyzer | [AvoidVariableNamedUnderscoreAnalyzer](https://github.com/philips-software/roslyn-analyzers/blob/main/Philips.CodeAnalysis.MaintainabilityAnalyzers/Naming/AvoidVariableNamedUnderscoreAnalyzer.cs)
+| CodeFix  | No |
+| Severity | Error |
+| Enabled By Default | Yes |
+
+## Introduction
 
 This rule flags variables (local variables, foreach variables, for loop variables, using variables, and out parameters) that are named exactly `_` (single underscore).
 
@@ -70,7 +73,7 @@ if (int.TryParse(input, out int result))
 
 ## Configuration
 
-This rule is enabled by default with Warning severity.
+This rule is enabled by default with Error severity.
 
 ## Suppression
 

Philips.CodeAnalysis.MaintainabilityAnalyzers/Naming/AvoidVariableNamedUnderscoreAnalyzer.cs

@@ -1,5 +1,7 @@
 // © 2019 Koninklijke Philips N.V. See License.md in the project root for license information.
 
+#pragma warning disable IDE0055 // Fix formatting
+
 using System.Linq;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
@@ -97,7 +99,7 @@ private void AnalyzeArgument(SyntaxNodeAnalysisContext context)
 				return;
 			}
 
-			// Check if it's a variable declaration (out int _)
+			// Check if it's a variable declaration
 			if (argument.Expression is DeclarationExpressionSyntax declaration)
 			{
 				if (declaration.Designation is SingleVariableDesignationSyntax variable)
@@ -111,6 +113,12 @@ private void AnalyzeArgument(SyntaxNodeAnalysisContext context)
 					var diagnostic = Diagnostic.Create(Rule, location, variable.Identifier.ValueText);
 					context.ReportDiagnostic(diagnostic);
 				}
+				else if (declaration.Designation is DiscardDesignationSyntax discard)
+				{
+					Location location = discard.UnderscoreToken.GetLocation();
+					var diagnostic = Diagnostic.Create(Rule, location, discard.UnderscoreToken.ValueText);
+					context.ReportDiagnostic(diagnostic);
+				}
 			}
 		}
 	}