Use pattern matching (RCS1146)

ChangeLog.md

@@ -34,6 +34,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix refactoring ([RR0014](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RR0014.md)) ([#988](https://github.com/josefpihrt/roslynator/pull/988)).
 - Fix refactoring ([RR0180](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RR0180.md)) ([#988](https://github.com/josefpihrt/roslynator/pull/988)).
 - Recognize `ArgumentNullException.ThrowIfNull` ([RCS1227](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1227.md)) ([#992](https://github.com/josefpihrt/roslynator/pull/992)).
+- Detect pattern matching in [RCS1146](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1146.md) ([#999](https://github.com/josefpihrt/roslynator/pull/999)).
 
 ## [4.1.2] - 2022-10-31
 

src/Analyzers.CodeFixes/CSharp/CodeFixes/UseConditionalAccessCodeFixProvider.cs

@@ -84,8 +84,8 @@ public override async Task RegisterCodeFixesAsync(CodeFixContext context)
         (ExpressionSyntax left, ExpressionSyntax right) = UseConditionalAccessAnalyzer.GetFixableExpressions(binaryExpression, kind, semanticModel, cancellationToken);
 
         NullCheckStyles allowedStyles = (kind == SyntaxKind.LogicalAndExpression)
-            ? NullCheckStyles.NotEqualsToNull
-            : NullCheckStyles.EqualsToNull;
+            ? (NullCheckStyles.NotEqualsToNull | NullCheckStyles.IsNotNull)
+            : (NullCheckStyles.EqualsToNull | NullCheckStyles.IsNull);
 
         NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(left, semanticModel, allowedStyles: allowedStyles, cancellationToken: cancellationToken);
 
@@ -190,7 +190,7 @@ int GetParenTokenDiff()
 
         StatementSyntax newStatement = statement;
 
-        NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(ifStatement.Condition, NullCheckStyles.NotEqualsToNull);
+        NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(ifStatement.Condition, NullCheckStyles.NotEqualsToNull | NullCheckStyles.IsNotNull);
 
         SimpleMemberInvocationStatementInfo invocationInfo = SyntaxInfo.SimpleMemberInvocationStatementInfo(statement);
 

src/Analyzers/CSharp/Analysis/UseConditionalAccessAnalyzer.cs

@@ -58,7 +58,9 @@ private static void AnalyzeIfStatement(SyntaxNodeAnalysisContext context)
         if (ifStatement.SpanContainsDirectives())
             return;
 
-        NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(ifStatement.Condition, allowedStyles: NullCheckStyles.NotEqualsToNull);
+        NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(
+            ifStatement.Condition,
+            allowedStyles: NullCheckStyles.NotEqualsToNull | NullCheckStyles.IsNotNull);
 
         ExpressionSyntax expression = nullCheck.Expression;
 
@@ -165,8 +167,8 @@ static bool ExistsImplicitConversionToBoolean(INamedTypeSymbol typeSymbol)
         CancellationToken cancellationToken)
     {
         NullCheckStyles allowedStyles = (binaryExpressionKind == SyntaxKind.LogicalAndExpression)
-            ? NullCheckStyles.NotEqualsToNull
-            : NullCheckStyles.EqualsToNull;
+            ? (NullCheckStyles.NotEqualsToNull | NullCheckStyles.IsNotNull)
+            : (NullCheckStyles.EqualsToNull | NullCheckStyles.IsNull);
 
         NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(left, semanticModel, allowedStyles: allowedStyles, cancellationToken: cancellationToken);
 

src/Tests/Analyzers.Tests/RCS1146UseConditionalAccessTests.cs

@@ -80,6 +80,35 @@ void M()
 ");
     }
 
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.UseConditionalAccess)]
+    public async Task Test_IfStatement_PatternMatching()
+    {
+        await VerifyDiagnosticAndFixAsync(@"
+class C
+{
+    void M()
+    {
+        C x = null;
+
+        [|if (x is not null)
+        {
+            x.M();
+        }|]
+    }
+}
+", @"
+class C
+{
+    void M()
+    {
+        C x = null;
+
+        x?.M();
+    }
+}
+");
+    }
+
     [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.UseConditionalAccess)]
     public async Task Test_LogicalAnd_ReferenceType()
     {
@@ -183,6 +212,32 @@ void M()
 ");
     }
 
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.UseConditionalAccess)]
+    public async Task Test_LogicalAnd_ReferenceType_PatternMatching()
+    {
+        await VerifyDiagnosticAndFixAsync(@"
+class Foo
+{
+    void M()
+    {
+        Foo x = null;
+
+        if ([|x is not null && !x.Equals(x)|]) { }
+    }
+}
+", @"
+class Foo
+{
+    void M()
+    {
+        Foo x = null;
+
+        if (x?.Equals(x) == false) { }
+    }
+}
+");
+    }
+
     [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.UseConditionalAccess)]
     public async Task Test_LogicalOr_ReferenceType()
     {