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Analyzer: Simplify argument null check (RCS1255) (#994)
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99 changes: 99 additions & 0 deletions
99
src/Analyzers/CSharp/Analysis/SimplifyArgumentNullCheckAnalyzer.cs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,99 @@ | ||
| // Copyright (c) Josef Pihrt and Contributors. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information. | ||
|
|
||
| using System.Collections.Immutable; | ||
| using System.Linq; | ||
| using Microsoft.CodeAnalysis; | ||
| using Microsoft.CodeAnalysis.CSharp; | ||
| using Microsoft.CodeAnalysis.CSharp.Syntax; | ||
| using Microsoft.CodeAnalysis.Diagnostics; | ||
| using Roslynator.CSharp.Syntax; | ||
|
|
||
| namespace Roslynator.CSharp.Analysis; | ||
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| [DiagnosticAnalyzer(LanguageNames.CSharp)] | ||
| public sealed class SimplifyArgumentNullCheckAnalyzer : BaseDiagnosticAnalyzer | ||
| { | ||
| private static ImmutableArray<DiagnosticDescriptor> _supportedDiagnostics; | ||
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| public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics | ||
| { | ||
| get | ||
| { | ||
| if (_supportedDiagnostics.IsDefault) | ||
| Immutable.InterlockedInitialize(ref _supportedDiagnostics, DiagnosticRules.SimplifyArgumentNullCheck); | ||
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| return _supportedDiagnostics; | ||
| } | ||
| } | ||
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| public override void Initialize(AnalysisContext context) | ||
| { | ||
| base.Initialize(context); | ||
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| context.RegisterSyntaxNodeAction(f => AnalyzeIfStatement(f), SyntaxKind.IfStatement); | ||
| } | ||
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| private static void AnalyzeIfStatement(SyntaxNodeAnalysisContext context) | ||
| { | ||
| var ifStatement = (IfStatementSyntax)context.Node; | ||
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| if (!ifStatement.IsSimpleIf()) | ||
| return; | ||
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| NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo( | ||
| ifStatement.Condition, | ||
| NullCheckStyles.EqualsToNull | NullCheckStyles.IsNull); | ||
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| if (!nullCheck.Success) | ||
| return; | ||
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| if (nullCheck.Expression is not IdentifierNameSyntax identifierName) | ||
| return; | ||
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| if (ifStatement.SingleNonBlockStatementOrDefault() is not ThrowStatementSyntax throwStatement) | ||
| return; | ||
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| if (throwStatement.Expression is not ObjectCreationExpressionSyntax objectCreation) | ||
| return; | ||
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| ExpressionSyntax expression = objectCreation.ArgumentList?.Arguments.SingleOrDefault(shouldThrow: false)?.Expression; | ||
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| if (expression is null) | ||
| return; | ||
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| if (ifStatement.ContainsUnbalancedIfElseDirectives()) | ||
| return; | ||
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| INamedTypeSymbol containingTypeSymbol = context.SemanticModel | ||
| .GetSymbol(objectCreation, context.CancellationToken)? | ||
| .ContainingType; | ||
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| if (containingTypeSymbol?.HasMetadataName(MetadataNames.System_ArgumentNullException) != true) | ||
| return; | ||
|
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| if (!containingTypeSymbol.GetMembers("ThrowIfNull").Any(f => f.IsKind(SymbolKind.Method))) | ||
| return; | ||
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| if (expression.IsKind(SyntaxKind.StringLiteralExpression)) | ||
| { | ||
| var literal = (LiteralExpressionSyntax)expression; | ||
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| if (string.Equals(identifierName.Identifier.ValueText, literal.Token.ValueText)) | ||
| ReportDiagnostic(context, ifStatement); | ||
| } | ||
| else if (expression is InvocationExpressionSyntax invocationExpression) | ||
| { | ||
| if (CSharpUtility.IsNameOfExpression(invocationExpression, context.SemanticModel, context.CancellationToken) | ||
| && invocationExpression.ArgumentList.Arguments.FirstOrDefault().Expression is IdentifierNameSyntax identifierName2 | ||
| && string.Equals(identifierName.Identifier.ValueText, identifierName2.Identifier.ValueText)) | ||
| { | ||
| ReportDiagnostic(context, ifStatement); | ||
| } | ||
| } | ||
| } | ||
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| private static void ReportDiagnostic(SyntaxNodeAnalysisContext context, IfStatementSyntax ifStatement) | ||
| { | ||
| context.ReportDiagnostic(DiagnosticRules.SimplifyArgumentNullCheck, ifStatement.IfKeyword); | ||
| } | ||
| } |
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118 changes: 118 additions & 0 deletions
118
src/Tests/Analyzers.Tests/RCS1255SimplifyArgumentNullCheckTests.cs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,118 @@ | ||
| // Copyright (c) Josef Pihrt and Contributors. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information. | ||
|
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| using System.Threading.Tasks; | ||
| using Microsoft.CodeAnalysis; | ||
| using Roslynator.CSharp.CodeFixes; | ||
| using Roslynator.Testing.CSharp; | ||
| using Xunit; | ||
|
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| namespace Roslynator.CSharp.Analysis.Tests; | ||
|
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| public class RCS1255SimplifyArgumentNullCheckTests : AbstractCSharpDiagnosticVerifier<SimplifyArgumentNullCheckAnalyzer, IfStatementCodeFixProvider> | ||
| { | ||
| public override DiagnosticDescriptor Descriptor { get; } = DiagnosticRules.SimplifyArgumentNullCheck; | ||
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| [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.SimplifyArgumentNullCheck)] | ||
| public async Task Test_IfStatement_Block_Nameof() | ||
| { | ||
| await VerifyDiagnosticAndFixAsync(@" | ||
| using System; | ||
| class C | ||
| { | ||
| C(string x) | ||
| { | ||
| [|if|] (x is null) | ||
| { | ||
| throw new ArgumentNullException(nameof(x)); | ||
| } | ||
| } | ||
| } | ||
| ", @" | ||
| using System; | ||
| class C | ||
| { | ||
| C(string x) | ||
| { | ||
| ArgumentNullException.ThrowIfNull(x); | ||
| } | ||
| } | ||
| "); | ||
| } | ||
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| [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.SimplifyArgumentNullCheck)] | ||
| public async Task Test_IfStatement_Block_Literal() | ||
| { | ||
| await VerifyDiagnosticAndFixAsync(@" | ||
| using System; | ||
| class C | ||
| { | ||
| C(string x) | ||
| { | ||
| [|if|] (x is null) | ||
| { | ||
| throw new ArgumentNullException(""x""); | ||
| } | ||
| } | ||
| } | ||
| ", @" | ||
| using System; | ||
| class C | ||
| { | ||
| C(string x) | ||
| { | ||
| ArgumentNullException.ThrowIfNull(x); | ||
| } | ||
| } | ||
| "); | ||
| } | ||
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| [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.SimplifyArgumentNullCheck)] | ||
| public async Task Test_IfStatement_Embedded_Nameof() | ||
| { | ||
| await VerifyDiagnosticAndFixAsync(@" | ||
| using System; | ||
| class C | ||
| { | ||
| C(string x) | ||
| { | ||
| [|if|] (x is null) | ||
| throw new ArgumentNullException(nameof(x)); | ||
| } | ||
| } | ||
| ", @" | ||
| using System; | ||
| class C | ||
| { | ||
| C(string x) | ||
| { | ||
| ArgumentNullException.ThrowIfNull(x); | ||
| } | ||
| } | ||
| "); | ||
| } | ||
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| [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.SimplifyArgumentNullCheck)] | ||
| public async Task TestNoDiagnostic_TwoArguments() | ||
| { | ||
| await VerifyNoDiagnosticAsync(@" | ||
| using System; | ||
| class C | ||
| { | ||
| C(string x) | ||
| { | ||
| if (x is null) | ||
| { | ||
| throw new ArgumentNullException(nameof(x), ""message""); | ||
| } | ||
| } | ||
| } | ||
| "); | ||
| } | ||
| } |
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