Merge pull request #30430 from Neme12/useAnotherLiteral

Code fix for CS8313, CS8363 (invalid default literal as case constant / pattern) to use another literal

src/Features/CSharp/Portable/CSharpFeaturesResources.Designer.cs

@@ -1261,6 +1261,15 @@ internal class CSharpFeaturesResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Use &apos;{0}&apos;.
+        /// </summary>
+        internal static string Use_0 {
+            get {
+                return ResourceManager.GetString("Use_0", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Use explicit type.
         /// </summary>

src/Features/CSharp/Portable/CSharpFeaturesResources.resx

@@ -572,6 +572,9 @@
   <data name="Remove_unused_variables" xml:space="preserve">
     <value>Remove unused variables</value>
   </data>
+  <data name="Use_0" xml:space="preserve">
+    <value>Use '{0}'</value>
+  </data>
   <data name="Add_missing_usings" xml:space="preserve">
     <value>Add missing usings</value>
     <comment>{Locked="using"} "using" is a C# keyword and should not be localized.</comment>

src/Features/CSharp/Portable/ReplaceDefaultLiteral/CSharpReplaceDefaultLiteralCodeFixProvider.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Immutable;
+using System.Composition;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.CSharp.Extensions;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Editing;
+using Microsoft.CodeAnalysis.Shared.Extensions;
+using Microsoft.CodeAnalysis.Text;
+
+namespace Microsoft.CodeAnalysis.CSharp.ReplaceDefaultLiteral
+{
+    [ExportCodeFixProvider(LanguageNames.CSharp, Name = PredefinedCodeFixProviderNames.ReplaceDefaultLiteral), Shared]
+    internal sealed class CSharpReplaceDefaultLiteralCodeFixProvider : CodeFixProvider
+    {
+        private const string CS8313 = nameof(CS8313); // A default literal 'default' is not valid as a case constant. Use another literal (e.g. '0' or 'null') as appropriate. If you intended to write the default label, use 'default:' without 'case'.
+        private const string CS8363 = nameof(CS8363); // A default literal 'default' is not valid as a pattern. Use another literal (e.g. '0' or 'null') as appropriate. To match everything, use a discard pattern 'var _'.
+
+        public override ImmutableArray<string> FixableDiagnosticIds { get; } =
+            ImmutableArray.Create(CS8313, CS8363);
+
+        public override FixAllProvider GetFixAllProvider()
+        {
+            // This code fix addresses very specific compiler errors. It's unlikely there will be more than 1 of them at a time.
+            return null;
+        }
+
+        public override async Task RegisterCodeFixesAsync(CodeFixContext context)
+        {
+            var syntaxRoot = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+            var token = syntaxRoot.FindToken(context.Span.Start);
+
+            if (token.Span == context.Span &&
+                token.IsKind(SyntaxKind.DefaultKeyword) &&
+                token.Parent.IsKind(SyntaxKind.DefaultLiteralExpression))
+            {
+                var defaultLiteral = (LiteralExpressionSyntax)token.Parent;
+                var semanticModel = await context.Document.GetSemanticModelAsync(context.CancellationToken).ConfigureAwait(false);
+
+                var (newExpression, displayText) = GetReplacementExpressionAndText(
+                    context.Document, semanticModel, defaultLiteral, context.CancellationToken);
+
+                if (newExpression != null)
+                {
+                    context.RegisterCodeFix(
+                        new MyCodeAction(
+                            c => ReplaceAsync(context.Document, context.Span, newExpression, c),
+                            displayText),
+                        context.Diagnostics);
+                }
+            }
+        }
+
+        private static async Task<Document> ReplaceAsync(
+            Document document, TextSpan span, SyntaxNode newExpression, CancellationToken cancellationToken)
+        {
+            var syntaxRoot = await document.GetSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
+
+            var defaultToken = syntaxRoot.FindToken(span.Start);
+            var defaultLiteral = (LiteralExpressionSyntax)defaultToken.Parent;
+
+            var newRoot = syntaxRoot.ReplaceNode(defaultLiteral, newExpression.WithTriviaFrom(defaultLiteral));
+            return document.WithSyntaxRoot(newRoot);
+        }
+
+        private static (SyntaxNode newExpression, string displayText) GetReplacementExpressionAndText(
+            Document document,
+            SemanticModel semanticModel,
+            LiteralExpressionSyntax defaultLiteral,
+            CancellationToken cancellationToken)
+        {
+            var generator = SyntaxGenerator.GetGenerator(document);
+
+            var type = semanticModel.GetTypeInfo(defaultLiteral, cancellationToken).ConvertedType;
+            if (type != null && type.TypeKind != TypeKind.Error)
+            {
+                if (IsFlagsEnum(type, semanticModel.Compilation) &&
+                    type.GetMembers("None").FirstOrDefault() is IFieldSymbol field && IsZero(field.ConstantValue))
+                {
+                    return GenerateMemberAccess("None");
+                }
+                else if (type.Equals(semanticModel.Compilation.GetTypeByMetadataName(typeof(CancellationToken).FullName)))
+                {
+                    return GenerateMemberAccess(nameof(CancellationToken.None));
+                }
+                else if (type.SpecialType == SpecialType.System_IntPtr || type.SpecialType == SpecialType.System_UIntPtr)
+                {
+                    return GenerateMemberAccess(nameof(IntPtr.Zero));
+                }
+                else if (semanticModel.GetConstantValue(defaultLiteral, cancellationToken) is var constant && constant.HasValue)
+                {
+                    var newLiteral = generator.LiteralExpression(constant.Value);
+                    return (newLiteral, newLiteral.ToString());
+                }
+                else if (!type.ContainsAnonymousType())
+                {
+                    var defaultExpression = generator.DefaultExpression(type);
+                    return (defaultExpression, $"default({type.ToDisplayString(SymbolDisplayFormat.MinimallyQualifiedFormat)})");
+                }
+            }
+
+            return default;
+
+            (SyntaxNode newExpression, string displayText) GenerateMemberAccess(string memberName)
+            {
+                var memberAccess = generator.MemberAccessExpression(generator.TypeExpression(type), memberName);
+                return (memberAccess, $"{type.ToDisplayString(SymbolDisplayFormat.MinimallyQualifiedFormat)}.{memberName}");
+            }
+        }
+
+        private static bool IsFlagsEnum(ITypeSymbol type, Compilation compilation)
+        {
+            var flagsAttribute = compilation.GetTypeByMetadataName(typeof(FlagsAttribute).FullName);
+            return type.TypeKind == TypeKind.Enum &&
+                   type.GetAttributes().Any(attribute => attribute.AttributeClass.Equals(flagsAttribute));
+        }
+
+        private static bool IsZero(object o)
+        {
+            switch (o)
+            {
+                case default(int):
+                case default(uint):
+                case default(byte):
+                case default(sbyte):
+                case default(short):
+                case default(ushort):
+                case default(long):
+                case default(ulong):
+                    return true;
+                default:
+                    return false;
+            }
+        }
+
+        private sealed class MyCodeAction : CodeAction.DocumentChangeAction
+        {
+            public MyCodeAction(Func<CancellationToken, Task<Document>> createChangedDocument, string literal)
+                : base(string.Format(CSharpFeaturesResources.Use_0, literal), createChangedDocument, CSharpFeaturesResources.Use_0)
+            {
+            }
+        }
+    }
+}

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.cs.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.de.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.es.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.fr.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.it.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.ja.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.ko.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.pl.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.pt-BR.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.ru.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.tr.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.zh-Hans.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/CSharp/Portable/xlf/CSharpFeaturesResources.zh-Hant.xlf

@@ -117,6 +117,11 @@
         <target state="new">Sort accessibility modifiers</target>
         <note />
       </trans-unit>
+      <trans-unit id="Use_0">
+        <source>Use '{0}'</source>
+        <target state="new">Use '{0}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="if_statement_can_be_simplified">
         <source>'if' statement can be simplified</source>
         <target state="new">'if' statement can be simplified</target>

src/Features/Core/Portable/CodeFixes/PredefinedCodeFixProviderNames.cs

@@ -41,6 +41,7 @@ internal static class PredefinedCodeFixProviderNames
         public const string MoveToTopOfFile = nameof(MoveToTopOfFile);
         public const string PopulateSwitch = nameof(PopulateSwitch);
         public const string QualifyMemberAccess = nameof(QualifyMemberAccess);
+        public const string ReplaceDefaultLiteral = nameof(ReplaceDefaultLiteral);
         public const string RemoveUnnecessaryCast = nameof(RemoveUnnecessaryCast);
         public const string DeclareAsNullable = nameof(DeclareAsNullable);
         public const string RemoveUnnecessaryImports = nameof(RemoveUnnecessaryImports);

src/Test/Utilities/Portable/Traits/Traits.cs

@@ -107,6 +107,7 @@ public static class Features
             public const string CodeActionsOrderModifiers = "CodeActions.OrderModifiers";
             public const string CodeActionsPopulateSwitch = "CodeActions.PopulateSwitch";
             public const string CodeActionsQualifyMemberAccess = "CodeActions.QualifyMemberAccess";
+            public const string CodeActionsReplaceDefaultLiteral = "CodeActions.ReplaceDefaultLiteral";
             public const string CodeActionsReplaceDocCommentTextWithTag = "CodeActions.ReplaceDocCommentTextWithTag";
             public const string CodeActionsReplaceMethodWithProperty = "CodeActions.ReplaceMethodWithProperty";
             public const string CodeActionsReplacePropertyWithMethods = "CodeActions.ReplacePropertyWithMethods";