Implement Use 'StartsWith' instead of 'IndexOf' analyzer

src/NetAnalyzers/Core/AnalyzerReleases.Unshipped.md

@@ -6,3 +6,4 @@ Rule ID | Category | Severity | Notes
 --------|----------|----------|-------
 CA1856 | Performance | Error | ConstantExpectedAnalyzer, [Documentation](https://docs.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1856)
 CA1857 | Performance | Warning | ConstantExpectedAnalyzer, [Documentation](https://docs.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1857)
+CA1858 | Performance | Info | UseStartsWithInsteadOfIndexOfComparisonWithZero, [Documentation](https://docs.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1858)

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/MicrosoftNetCoreAnalyzersResources.resx

@@ -2031,4 +2031,13 @@
   <data name="PreventNumericIntPtrUIntPtrBehavioralChangesConversionThrowsMessage" xml:space="preserve">
     <value>Starting with .NET 7 the explicit conversion '{0}' will throw when overflowing in a checked context. Wrap the expression with an 'unchecked' statement to restore the .NET 6 behavior.</value>
   </data>
+  <data name="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription" xml:space="preserve">
+    <value>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</value>
+  </data>
+  <data name="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage" xml:space="preserve">
+    <value>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</value>
+  </data>
+  <data name="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle" xml:space="preserve">
+    <value>Use 'StartsWith'</value>
+  </data>
 </root>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/Performance/UseStartsWithInsteadOfIndexOfComparisonWithZero.Fixer.cs

@@ -0,0 +1,46 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Composition;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CodeActions;
+using Microsoft.CodeAnalysis.CodeFixes;
+using Microsoft.CodeAnalysis.Editing;
+
+namespace Microsoft.NetCore.Analyzers.Performance
+{
+    [ExportCodeFixProvider(LanguageNames.CSharp, LanguageNames.VisualBasic), Shared]
+    public sealed class UseStartsWithInsteadOfIndexOfComparisonWithZeroCodeFix : CodeFixProvider
+    {
+        public override ImmutableArray<string> FixableDiagnosticIds { get; } = ImmutableArray.Create(UseStartsWithInsteadOfIndexOfComparisonWithZero.RuleId);
+
+        public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
+        {
+            var document = context.Document;
+            var diagnostic = context.Diagnostics[0];
+            var root = await document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
+            var node = root.FindNode(context.Span, getInnermostNodeForTie: true);
+            var instance = root.FindNode(diagnostic.AdditionalLocations[0].SourceSpan);
+            var argument = root.FindNode(diagnostic.AdditionalLocations[1].SourceSpan);
+
+            context.RegisterCodeFix(
+                CodeAction.Create(MicrosoftNetCoreAnalyzersResources.UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle,
+                createChangedDocument: cancellationToken =>
+                {
+                    var generator = SyntaxGenerator.GetGenerator(document);
+                    var expression = generator.InvocationExpression(generator.MemberAccessExpression(instance, "StartsWith"), argument);
+
+                    var shouldNegate = diagnostic.Properties.TryGetValue(UseStartsWithInsteadOfIndexOfComparisonWithZero.ShouldNegateKey, out _);
+                    if (shouldNegate)
+                    {
+                        expression = generator.LogicalNotExpression(expression);
+                    }
+
+                    return Task.FromResult(document.WithSyntaxRoot(root.ReplaceNode(node, expression)));
+                },
+                equivalenceKey: nameof(MicrosoftNetCoreAnalyzersResources.UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle)),
+                context.Diagnostics);
+        }
+    }
+}

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/Performance/UseStartsWithInsteadOfIndexOfComparisonWithZero.cs

@@ -0,0 +1,91 @@
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq;
+using Analyzer.Utilities;
+using Analyzer.Utilities.Extensions;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Operations;
+
+namespace Microsoft.NetCore.Analyzers.Performance
+{
+    using static MicrosoftNetCoreAnalyzersResources;
+
+    [DiagnosticAnalyzer(LanguageNames.CSharp, LanguageNames.VisualBasic)]
+    public sealed class UseStartsWithInsteadOfIndexOfComparisonWithZero : DiagnosticAnalyzer
+    {
+        internal const string RuleId = "CA1858";
+        internal const string ShouldNegateKey = "ShouldNegate";
+
+        internal static readonly DiagnosticDescriptor Rule = DiagnosticDescriptorHelper.Create(
+            id: "CA1858",
+            title: CreateLocalizableResourceString(nameof(UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle)),
+            messageFormat: CreateLocalizableResourceString(nameof(UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage)),
+            category: DiagnosticCategory.Performance,
+            ruleLevel: RuleLevel.IdeSuggestion,
+            description: CreateLocalizableResourceString(nameof(UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription)),
+            isPortedFxCopRule: false,
+            isDataflowRule: false
+            );
+
+        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; } = ImmutableArray.Create(Rule);
+
+        public override void Initialize(AnalysisContext context)
+        {
+            context.EnableConcurrentExecution();
+            context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+
+            context.RegisterCompilationStartAction(context =>
+            {
+                var stringType = context.Compilation.GetSpecialType(SpecialType.System_String);
+                if (stringType.GetMembers("StartsWith").FirstOrDefault() is not IMethodSymbol ||
+                    stringType.GetMembers("IndexOf").FirstOrDefault() is not IMethodSymbol indexOfSymbol)
+                {
+                    return;
+                }
+
+                context.RegisterOperationAction(context =>
+                {
+                    var binaryOperation = (IBinaryOperation)context.Operation;
+                    if (binaryOperation.OperatorKind is not (BinaryOperatorKind.Equals or BinaryOperatorKind.NotEquals))
+                    {
+                        return;
+                    }
+
+                    if (IsIndexOfComparedWithZero(binaryOperation.LeftOperand, binaryOperation.RightOperand, indexOfSymbol, out var instanceLocation, out var argumentLocation) ||
+                        IsIndexOfComparedWithZero(binaryOperation.RightOperand, binaryOperation.LeftOperand, indexOfSymbol, out instanceLocation, out argumentLocation))
+                    {
+                        var properties = ImmutableDictionary<string, string?>.Empty;
+                        if (binaryOperation.OperatorKind == BinaryOperatorKind.NotEquals)
+                        {
+                            properties = properties.Add(ShouldNegateKey, "");
+                        }
+
+                        context.ReportDiagnostic(binaryOperation.CreateDiagnostic(Rule, additionalLocations: ImmutableArray.Create(instanceLocation, argumentLocation), properties: properties));
+                    }
+
+                }, OperationKind.Binary);
+            });
+        }
+
+        private static bool IsIndexOfComparedWithZero(IOperation left, IOperation right, IMethodSymbol indexOfSymbol, [NotNullWhen(true)] out Location? instanceLocation, [NotNullWhen(true)] out Location? argumentLocation)
+        {
+            if (right.ConstantValue is not { HasValue: true, Value: 0 } ||
+                left is not IInvocationOperation invocation ||
+                invocation.Arguments.Length != 1 ||
+                SymbolEqualityComparer.Default.Equals(invocation.TargetMethod, indexOfSymbol))
+            {
+                instanceLocation = null;
+                argumentLocation = null;
+                return false;
+            }
+
+
+            instanceLocation = invocation.Instance.Syntax.GetLocation();
+            argumentLocation = invocation.Arguments[0].Syntax.GetLocation();
+            return true;
+        }
+    }
+}

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.cs.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">Preferovat možnost Vymazat před možností Fill</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">Použít string.Equals</target>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.de.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">„Clear“ vor „Fill“ bevorzugen</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">"string.Equals" verwenden</target>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.es.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">Preferir "Clear" en lugar de "Fill"</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">Use 'string.Equals'</target>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.fr.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">Préférer 'Effacer' à 'Remplissage'</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">Utilisez ’String. Equals</target>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.it.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">Preferisci 'Cancella' a 'Riempimento'</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">Usare 'string.Equals'</target>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.ja.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">'塗りつぶし' よりも 'クリア' を優先する</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">'string.Equals' を使用します。</target>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.ko.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">'채우기'보다 '지우기' 선호</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">'string.Equals' 사용</target>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.pl.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">Preferuj opcję „Wyczyść” niż „Wypełnij”</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">Użyj ciągu „string. Equals”</target>

src/NetAnalyzers/Core/Microsoft.NetCore.Analyzers/xlf/MicrosoftNetCoreAnalyzersResources.pt-BR.xlf

@@ -2987,6 +2987,21 @@
         <target state="translated">Preferir 'Clear' ao invés de 'Fill'</target>
         <note />
       </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroDescription">
+        <source>It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</source>
+        <target state="new">It is both clearer and likely faster to use 'StartsWith' instead of comparing the result of 'IndexOf' to zero.</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroMessage">
+        <source>Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</source>
+        <target state="new">Use 'StartsWith' instead of comparing the result of 'IndexOf' to 0</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="UseStartsWithInsteadOfIndexOfComparisonWithZeroTitle">
+        <source>Use 'StartsWith'</source>
+        <target state="new">Use 'StartsWith'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UseStringEqualsOverStringCompareCodeFixTitle">
         <source>Use 'string.Equals'</source>
         <target state="translated">Use 'string. Igual a'</target>