Use compound assignment

src/Workspaces/CSharp/Portable/CodeGeneration/CSharpCodeGenerationHelpers.cs

@@ -36,7 +36,7 @@ internal static class CSharpCodeGenerationHelpers
             CodeGenerationOptions options,
             Accessibility defaultAccessibility)
         {
-            options = options ?? CodeGenerationOptions.Default;
+            options ??= CodeGenerationOptions.Default;
             if (!options.GenerateDefaultAccessibility && accessibility == defaultAccessibility)
             {
                 return;

src/Workspaces/CSharp/Portable/CodeGeneration/CSharpSyntaxGenerator.cs

@@ -1501,7 +1501,7 @@ public override SyntaxNode WithModifiers(SyntaxNode declaration, DeclarationModi
 
         private SyntaxNode WithModifiersInternal(SyntaxNode declaration, DeclarationModifiers modifiers)
         {
-            modifiers = modifiers & GetAllowedModifiers(declaration.Kind());
+            modifiers &= GetAllowedModifiers(declaration.Kind());
             var existingModifiers = this.GetModifiers(declaration);
 
             if (modifiers != existingModifiers)
@@ -1697,51 +1697,51 @@ private static void GetAccessibilityAndModifiers(SyntaxTokenList modifierList, o
                         break;
 
                     case SyntaxKind.AbstractKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Abstract;
+                        modifiers |= DeclarationModifiers.Abstract;
                         break;
 
                     case SyntaxKind.NewKeyword:
-                        modifiers = modifiers | DeclarationModifiers.New;
+                        modifiers |= DeclarationModifiers.New;
                         break;
 
                     case SyntaxKind.OverrideKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Override;
+                        modifiers |= DeclarationModifiers.Override;
                         break;
 
                     case SyntaxKind.VirtualKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Virtual;
+                        modifiers |= DeclarationModifiers.Virtual;
                         break;
 
                     case SyntaxKind.StaticKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Static;
+                        modifiers |= DeclarationModifiers.Static;
                         break;
 
                     case SyntaxKind.AsyncKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Async;
+                        modifiers |= DeclarationModifiers.Async;
                         break;
 
                     case SyntaxKind.ConstKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Const;
+                        modifiers |= DeclarationModifiers.Const;
                         break;
 
                     case SyntaxKind.ReadOnlyKeyword:
-                        modifiers = modifiers | DeclarationModifiers.ReadOnly;
+                        modifiers |= DeclarationModifiers.ReadOnly;
                         break;
 
                     case SyntaxKind.SealedKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Sealed;
+                        modifiers |= DeclarationModifiers.Sealed;
                         break;
 
                     case SyntaxKind.UnsafeKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Unsafe;
+                        modifiers |= DeclarationModifiers.Unsafe;
                         break;
 
                     case SyntaxKind.PartialKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Partial;
+                        modifiers |= DeclarationModifiers.Partial;
                         break;
 
                     case SyntaxKind.RefKeyword:
-                        modifiers = modifiers | DeclarationModifiers.Ref;
+                        modifiers |= DeclarationModifiers.Ref;
                         break;
                 }
             }

src/Workspaces/CSharp/Portable/CodeGeneration/ConstructorGenerator.cs

@@ -44,7 +44,7 @@ private static MemberDeclarationSyntax LastConstructorOrField(SyntaxList<MemberD
             IMethodSymbol constructor, CodeGenerationDestination destination,
             Workspace workspace, CodeGenerationOptions options, ParseOptions parseOptions)
         {
-            options = options ?? CodeGenerationOptions.Default;
+            options ??= CodeGenerationOptions.Default;
 
             var reusableSyntax = GetReuseableSyntaxNodeForSymbol<ConstructorDeclarationSyntax>(constructor, options);
             if (reusableSyntax != null)

src/Workspaces/CSharp/Portable/CodeGeneration/DestructorGenerator.cs

@@ -36,7 +36,7 @@ private static MemberDeclarationSyntax LastConstructorOrField(SyntaxList<MemberD
         internal static DestructorDeclarationSyntax GenerateDestructorDeclaration(
             IMethodSymbol destructor, CodeGenerationDestination destination, CodeGenerationOptions options)
         {
-            options = options ?? CodeGenerationOptions.Default;
+            options ??= CodeGenerationOptions.Default;
 
             var reusableSyntax = GetReuseableSyntaxNodeForSymbol<DestructorDeclarationSyntax>(destructor, options);
             if (reusableSyntax != null)

src/Workspaces/CSharp/Portable/CodeGeneration/MethodGenerator.cs

@@ -66,7 +66,7 @@ internal static class MethodGenerator
             Workspace workspace, CodeGenerationOptions options,
             ParseOptions parseOptions)
         {
-            options = options ?? CodeGenerationOptions.Default;
+            options ??= CodeGenerationOptions.Default;
 
             var reusableSyntax = GetReuseableSyntaxNodeForSymbol<MethodDeclarationSyntax>(method, options);
             if (reusableSyntax != null)

src/Workspaces/CSharp/Portable/CodeGeneration/NamedTypeGenerator.cs

@@ -64,7 +64,7 @@ internal static class NamedTypeGenerator
             CodeGenerationOptions options,
             CancellationToken cancellationToken)
         {
-            options = options ?? CodeGenerationOptions.Default;
+            options ??= CodeGenerationOptions.Default;
 
             var declaration = GetDeclarationSyntaxWithoutMembers(namedType, destination, options);
 

src/Workspaces/CSharp/Portable/CodeGeneration/NamespaceGenerator.cs

@@ -58,7 +58,7 @@ internal static class NamespaceGenerator
             CodeGenerationOptions options,
             CancellationToken cancellationToken)
         {
-            options = options ?? CodeGenerationOptions.Default;
+            options ??= CodeGenerationOptions.Default;
             GetNameAndInnermostNamespace(@namespace, options, out var name, out var innermostNamespace);
 
             var declaration = GetDeclarationSyntaxWithoutMembers(@namespace, innermostNamespace, name, options);

src/Workspaces/CSharp/Portable/Extensions/ContextQuery/SyntaxTreeExtensions.cs

@@ -225,7 +225,7 @@ public static bool IsAttributeNameContext(this SyntaxTree syntaxTree, int positi
                 return false;
             }
 
-            validTypeDeclarations = validTypeDeclarations ?? SpecializedCollections.EmptySet<SyntaxKind>();
+            validTypeDeclarations ??= SpecializedCollections.EmptySet<SyntaxKind>();
 
             // Check many of the simple cases first.
             var leftToken = contextOpt != null
@@ -262,7 +262,7 @@ public static bool IsAttributeNameContext(this SyntaxTree syntaxTree, int positi
                 return false;
             }
 
-            validModifiers = validModifiers ?? SpecializedCollections.EmptySet<SyntaxKind>();
+            validModifiers ??= SpecializedCollections.EmptySet<SyntaxKind>();
 
             if (modifierTokens.IsSubsetOf(validModifiers))
             {
@@ -517,7 +517,7 @@ public static bool IsAttributeNameContext(this SyntaxTree syntaxTree, int positi
                 ? contextOpt.ContainingTypeDeclaration
                 : syntaxTree.GetContainingTypeDeclaration(position, cancellationToken);
 
-            validTypeDeclarations = validTypeDeclarations ?? SpecializedCollections.EmptySet<SyntaxKind>();
+            validTypeDeclarations ??= SpecializedCollections.EmptySet<SyntaxKind>();
 
             if (typeDecl != null)
             {
@@ -570,7 +570,7 @@ public static bool IsAttributeNameContext(this SyntaxTree syntaxTree, int positi
                 return false;
             }
 
-            validModifiers = validModifiers ?? SpecializedCollections.EmptySet<SyntaxKind>();
+            validModifiers ??= SpecializedCollections.EmptySet<SyntaxKind>();
 
             if (modifierTokens.IsProperSubsetOf(validModifiers))
             {

src/Workspaces/CSharp/Portable/Extensions/SemanticModelExtensions.cs

@@ -309,7 +309,7 @@ private static bool CanBindToken(SyntaxToken token)
             IList<string> reservedNames,
             CancellationToken cancellationToken)
         {
-            reservedNames = reservedNames ?? SpecializedCollections.EmptyList<string>();
+            reservedNames ??= SpecializedCollections.EmptyList<string>();
 
             // We can't change the names of named parameters.  Any other names we're flexible on.
             var isFixed = reservedNames.Select(s => true).Concat(
@@ -328,7 +328,7 @@ private static bool CanBindToken(SyntaxToken token)
             NamingRule parameterNamingRule,
             CancellationToken cancellationToken)
         {
-            reservedNames = reservedNames ?? SpecializedCollections.EmptyList<string>();
+            reservedNames ??= SpecializedCollections.EmptyList<string>();
 
             // We can't change the names of named parameters.  Any other names we're flexible on.
             var isFixed = reservedNames.Select(s => true).Concat(
@@ -360,7 +360,7 @@ private static ImmutableArray<ParameterName> GenerateNames(IList<string> reserve
             IList<string> reservedNames,
             CancellationToken cancellationToken)
         {
-            reservedNames = reservedNames ?? SpecializedCollections.EmptyList<string>();
+            reservedNames ??= SpecializedCollections.EmptyList<string>();
 
             // We can't change the names of named parameters.  Any other names we're flexible on.
             var isFixed = reservedNames.Select(s => true).Concat(
@@ -379,7 +379,7 @@ private static ImmutableArray<ParameterName> GenerateNames(IList<string> reserve
             NamingRule parameterNamingRule,
             CancellationToken cancellationToken)
         {
-            reservedNames = reservedNames ?? SpecializedCollections.EmptyList<string>();
+            reservedNames ??= SpecializedCollections.EmptyList<string>();
 
             // We can't change the names of named parameters.  Any other names we're flexible on.
             var isFixed = reservedNames.Select(s => true).Concat(
@@ -403,7 +403,7 @@ public static ISet<INamespaceSymbol> GetUsingNamespacesInScope(this SemanticMode
                     var symbolInfo = semanticModel.GetSymbolInfo(@using.Name);
                     if (symbolInfo.Symbol != null && symbolInfo.Symbol.Kind == SymbolKind.Namespace)
                     {
-                        result = result ?? new HashSet<INamespaceSymbol>();
+                        result ??= new HashSet<INamespaceSymbol>();
                         result.Add((INamespaceSymbol)symbolInfo.Symbol);
                     }
                 }

src/Workspaces/CSharp/Portable/FindSymbols/CSharpDeclaredSymbolInfoFactoryService.cs

@@ -97,7 +97,7 @@ private void ProcessUsings(List<Dictionary<string, string>> aliasMaps, SyntaxLis
                     var mappedName = GetTypeName(usingDecl.Name);
                     if (mappedName != null)
                     {
-                        aliasMap = aliasMap ?? AllocateAliasMap();
+                        aliasMap ??= AllocateAliasMap();
 
                         // If we have:  using X = Goo, then we store a mapping from X -> Goo
                         // here.  That way if we see a class that inherits from X we also state

src/Workspaces/CSharp/Portable/LanguageServices/CSharpSyntaxTreeFactoryService.cs

@@ -46,13 +46,13 @@ public override ParseOptions GetDefaultParseOptionsWithLatestLanguageVersion()
 
             public override SyntaxTree CreateSyntaxTree(string fileName, ParseOptions options, Encoding encoding, SyntaxNode root)
             {
-                options = options ?? GetDefaultParseOptions();
+                options ??= GetDefaultParseOptions();
                 return SyntaxFactory.SyntaxTree(root, options, fileName, encoding);
             }
 
             public override SyntaxTree ParseSyntaxTree(string filePath, ParseOptions options, SourceText text, ImmutableDictionary<string, ReportDiagnostic> treeDiagnosticReportingOptionsOpt, CancellationToken cancellationToken)
             {
-                options = options ?? GetDefaultParseOptions();
+                options ??= GetDefaultParseOptions();
                 return SyntaxFactory.ParseSyntaxTree(text, options, filePath, treeDiagnosticReportingOptionsOpt, cancellationToken: cancellationToken);
             }
 

src/Workspaces/CSharp/Portable/Rename/CSharpRenameRewriterLanguageService.cs

@@ -589,7 +589,7 @@ private SyntaxToken RenameToken(SyntaxToken oldToken, SyntaxToken newToken, stri
 
                     if (!string.IsNullOrEmpty(suffix))
                     {
-                        currentNewIdentifier = currentNewIdentifier + suffix;
+                        currentNewIdentifier += suffix;
                     }
                 }