Added this usage rule & code fix

app/SourceCodeRules/SourceCodeRules/AnalyzerReleases.Shipped.md

@@ -3,8 +3,9 @@
 ### New Rules
 
  Rule ID   | Category | Severity | Notes                       
------------|----------|----------|------------------------
+-----------|----------|----------|-----------------------------
  MWAIS0001 | Usage    | Error    | ProviderAccessAnalyzer      
  MWAIS0002 | Naming   | Error    | ConstStaticAnalyzer         
  MWAIS0003 | Naming   | Error    | UnderscorePrefixAnalyzer    
  MWAIS0004 | Usage    | Error    | RandomInstantiationAnalyzer 
+ MWAIS0005 | Usage    | Error    | ThisUsageAnalyzer           

app/SourceCodeRules/SourceCodeRules/Identifier.cs

@@ -6,4 +6,5 @@ public static class Identifier
     public const string CONST_STATIC_ANALYZER = $"{Tools.ID_PREFIX}0002";
     public const string UNDERSCORE_PREFIX_ANALYZER = $"{Tools.ID_PREFIX}0003";
     public const string RANDOM_INSTANTIATION_ANALYZER = $"{Tools.ID_PREFIX}0004";
+    public const string THIS_USAGE_ANALYZER = $"{Tools.ID_PREFIX}0005";
 }

app/SourceCodeRules/SourceCodeRules/UsageAnalyzers/ThisUsageAnalyzer.cs

@@ -0,0 +1,236 @@
+using System.Collections.Immutable;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace SourceCodeRules.UsageAnalyzers;
+#pragma warning disable RS1038
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+#pragma warning restore RS1038
+public sealed class ThisUsageAnalyzer : DiagnosticAnalyzer
+{
+    private const string DIAGNOSTIC_ID = Identifier.THIS_USAGE_ANALYZER;
+    
+    private static readonly string TITLE = "`this.` must be used";
+    
+    private static readonly string MESSAGE_FORMAT = "`this.` must be used to access variables, methods, and properties";
+    
+    private static readonly string DESCRIPTION = MESSAGE_FORMAT;
+    
+    private const string CATEGORY = "Usage";
+    
+    private static readonly DiagnosticDescriptor RULE = new(DIAGNOSTIC_ID, TITLE, MESSAGE_FORMAT, CATEGORY, DiagnosticSeverity.Error, isEnabledByDefault: true, description: DESCRIPTION);
+    
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => [RULE];
+    
+    public override void Initialize(AnalysisContext context)
+    {
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+        context.EnableConcurrentExecution();
+        context.RegisterSyntaxNodeAction(this.AnalyzeIdentifier, SyntaxKind.IdentifierName);
+        context.RegisterSyntaxNodeAction(this.AnalyzeGenericName, SyntaxKind.GenericName);
+    }
+    
+    private void AnalyzeGenericName(SyntaxNodeAnalysisContext context)
+    {
+        var genericNameSyntax = (GenericNameSyntax)context.Node;
+        
+        // Skip if already part of a 'this' expression
+        if (IsAccessedThroughThis(genericNameSyntax))
+            return;
+            
+        if (IsWithinInitializer(genericNameSyntax))
+            return;
+        
+        if (IsPartOfMemberAccess(genericNameSyntax))
+            return;
+        
+        // Get symbol info for the generic name
+        var symbolInfo = context.SemanticModel.GetSymbolInfo(genericNameSyntax);
+        var symbol = symbolInfo.Symbol;
+        
+        if (symbol == null)
+            return;
+            
+        // Skip static methods
+        if (symbol.IsStatic)
+            return;
+            
+        // Skip local functions
+        if (symbol is IMethodSymbol methodSymbol && IsLocalFunction(methodSymbol))
+            return;
+        
+        // Get the containing type of the current context
+        var containingSymbol = context.ContainingSymbol;
+        var currentType = containingSymbol?.ContainingType;
+        
+        // If we're in a static context, allow accessing members without this
+        if (IsInStaticContext(containingSymbol))
+            return;
+        
+        if (symbol is IMethodSymbol)
+        {
+            var containingType = symbol.ContainingType;
+            
+            // If the symbol is a member of the current type or a base type, then require this
+            if (currentType != null && (SymbolEqualityComparer.Default.Equals(containingType, currentType) || 
+                                        IsBaseTypeOf(containingType, currentType)))
+            {
+                var diagnostic = Diagnostic.Create(RULE, genericNameSyntax.Identifier.GetLocation());
+                context.ReportDiagnostic(diagnostic);
+            }
+        }
+    }
+    
+    private void AnalyzeIdentifier(SyntaxNodeAnalysisContext context)
+    {
+        var identifierNameSyntax = (IdentifierNameSyntax)context.Node;
+        
+        // Skip if this identifier is part of a generic name - we'll handle that separately
+        if (identifierNameSyntax.Parent is GenericNameSyntax)
+            return;
+        
+        // Skip if already part of a 'this' expression
+        if (IsAccessedThroughThis(identifierNameSyntax))
+            return;
+            
+        if (IsWithinInitializer(identifierNameSyntax))
+            return;
+        
+        if (IsPartOfMemberAccess(identifierNameSyntax))
+            return;
+        
+        // Also skip if it's part of static import statements
+        if (IsPartOfUsingStaticDirective(identifierNameSyntax))
+            return;
+            
+        // Skip if it's part of a namespace or type name
+        if (IsPartOfNamespaceOrTypeName(identifierNameSyntax))
+            return;
+        
+        // Get symbol info
+        var symbolInfo = context.SemanticModel.GetSymbolInfo(identifierNameSyntax);
+        var symbol = symbolInfo.Symbol;
+        
+        if (symbol == null)
+            return;
+            
+        // Skip local variables, parameters, and range variables
+        if (symbol.Kind is SymbolKind.Local or SymbolKind.Parameter or SymbolKind.RangeVariable or SymbolKind.TypeParameter)
+            return;
+            
+        // Skip types and namespaces
+        if (symbol.Kind is SymbolKind.NamedType or SymbolKind.Namespace)
+            return;
+        
+        // Explicitly check if this is a local function
+        if (symbol is IMethodSymbol methodSymbol && IsLocalFunction(methodSymbol))
+            return;
+            
+        // Get the containing type of the current context
+        var containingSymbol = context.ContainingSymbol;
+        var currentType = containingSymbol?.ContainingType;
+        
+        // If we're in a static context, allow accessing members without this
+        if (IsInStaticContext(containingSymbol))
+            return;
+            
+        // Now check if the symbol is an instance member of the current class
+        if (symbol is IFieldSymbol or IPropertySymbol or IMethodSymbol or IEventSymbol)
+        {
+            // Skip static members
+            if (symbol.IsStatic)
+                return;
+                
+            // Skip constants
+            if (symbol is IFieldSymbol { IsConst: true })
+                return;
+            
+            var containingType = symbol.ContainingType;
+            
+            // If the symbol is a member of the current type or a base type, then require this
+            if (currentType != null && (SymbolEqualityComparer.Default.Equals(containingType, currentType) || 
+                                        IsBaseTypeOf(containingType, currentType)))
+            {
+                var diagnostic = Diagnostic.Create(RULE, identifierNameSyntax.GetLocation());
+                context.ReportDiagnostic(diagnostic);
+            }
+        }
+    }
+    
+    private static bool IsLocalFunction(IMethodSymbol methodSymbol) => methodSymbol.MethodKind is MethodKind.LocalFunction;
+
+    private static bool IsBaseTypeOf(INamedTypeSymbol baseType, INamedTypeSymbol derivedType)
+    {
+        var currentType = derivedType.BaseType;
+        while (currentType != null)
+        {
+            if (SymbolEqualityComparer.Default.Equals(currentType, baseType))
+                return true;
+                
+            currentType = currentType.BaseType;
+        }
+        
+        return false;
+    }
+    
+    private static bool IsInStaticContext(ISymbol? containingSymbol) => containingSymbol?.IsStatic is true;
+
+    private static bool IsAccessedThroughThis(SyntaxNode node)
+    {
+        if (node.Parent is MemberAccessExpressionSyntax memberAccess)
+            if (memberAccess.Expression is ThisExpressionSyntax && memberAccess.Name == node)
+                return true;
+        
+        return false;
+    }
+    
+    private static bool IsWithinInitializer(SyntaxNode node)
+    {
+        for (var current = node.Parent; current != null; current = current.Parent)
+            if (current is InitializerExpressionSyntax)
+                return true;
+        
+        return false;
+    }
+    
+    private static bool IsPartOfMemberAccess(SyntaxNode node)
+    {
+        // Check if the node is part of a member access expression where the expression is not 'this':
+        if (node.Parent is MemberAccessExpressionSyntax memberAccess)
+        {
+            // If the member access expression is 'this', it's allowed:
+            if (memberAccess.Expression is ThisExpressionSyntax)
+                return false;
+            
+            // If the member access expression is something else (e.g., instance.Member), skip:
+            if (memberAccess.Name == node)
+                return true;
+        }
+        
+        // Also check for conditional access expressions (e.g., instance?.Member):
+        if (node.Parent is ConditionalAccessExpressionSyntax)
+            return true;
+        
+        return false;
+    }
+    
+    private static bool IsPartOfUsingStaticDirective(SyntaxNode node)
+    {
+        for (var current = node.Parent; current != null; current = current.Parent)
+            if (current is UsingDirectiveSyntax)
+                return true;
+        
+        return false;
+    }
+    
+    private static bool IsPartOfNamespaceOrTypeName(SyntaxNode node)
+    {
+        // Check if a node is part of a namespace, class, or type declaration:
+        if (node.Parent is NameSyntax && node.Parent is not MemberAccessExpressionSyntax)
+            return true;
+            
+        return false;
+    }
+}

app/SourceCodeRules/SourceCodeRules/UsageCodeFixes/ThisUsageCodeFixProvider.cs

@@ -0,0 +1,71 @@
+using System.Collections.Immutable;
+using System.Composition;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace SourceCodeRules.UsageCodeFixes;
+
+[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(ThisUsageCodeFixProvider)), Shared]
+public class ThisUsageCodeFixProvider : CodeFixProvider
+{
+    private const string TITLE = "Add 'this.' prefix";
+    
+    public sealed override ImmutableArray<string> FixableDiagnosticIds => [Identifier.THIS_USAGE_ANALYZER];
+    
+    public sealed override FixAllProvider GetFixAllProvider() => WellKnownFixAllProviders.BatchFixer;
+    
+    public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
+    {
+        var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken);
+        if (root == null)
+            return;
+        
+        var diagnostic = context.Diagnostics.First();
+        var diagnosticSpan = diagnostic.Location.SourceSpan;
+        var node = root.FindNode(diagnosticSpan);
+        
+        if (node is IdentifierNameSyntax identifierNode)
+        {
+            context.RegisterCodeFix(
+                CodeAction.Create(
+                    title: TITLE,
+                    createChangedDocument: c => AddThisPrefixAsync(context.Document, identifierNode, c),
+                    equivalenceKey: nameof(ThisUsageCodeFixProvider)),
+                diagnostic);
+        }
+        else if (node is GenericNameSyntax genericNameNode)
+        {
+            context.RegisterCodeFix(
+                CodeAction.Create(
+                    title: TITLE,
+                    createChangedDocument: c => AddThisPrefixAsync(context.Document, genericNameNode, c),
+                    equivalenceKey: nameof(ThisUsageCodeFixProvider)),
+                diagnostic);
+        }
+    }
+    
+    private static async Task<Document> AddThisPrefixAsync(Document document, SyntaxNode node, CancellationToken cancellationToken)
+    {
+        var root = await document.GetSyntaxRootAsync(cancellationToken);
+        if (root == null)
+            return document;
+        
+        var thisExpression = SyntaxFactory.ThisExpression();
+        var leadingTrivia = node.GetLeadingTrivia();
+        var memberAccessExpression = SyntaxFactory.MemberAccessExpression(
+                SyntaxKind.SimpleMemberAccessExpression,
+                thisExpression.WithLeadingTrivia(leadingTrivia), 
+                ((SimpleNameSyntax)node).WithLeadingTrivia(SyntaxTriviaList.Empty))
+            .WithTrailingTrivia(node.GetTrailingTrivia());
+
+        var newRoot = root.ReplaceNode(node, memberAccessExpression);
+        return document.WithSyntaxRoot(newRoot);
+    }
+}