Change approach to check for Nullability

SonarSource · Feb 13, 2023 · 53fd779 · 53fd779
1 parent 92bd87d
commit 53fd779
Show file tree

Hide file tree

Showing 2 changed files with 29 additions and 22 deletions.
diff --git a/analyzers/src/SonarAnalyzer.CSharp/Rules/RedundantCast.cs b/analyzers/src/SonarAnalyzer.CSharp/Rules/RedundantCast.cs
@@ -64,32 +64,21 @@ private static void CheckCastExpression(SonarSyntaxNodeReportingContext context,
             return;
         }
 
-        var expressionType = context.SemanticModel.GetTypeInfo(expression).Type;
+        var expressionTypeInfo = context.SemanticModel.GetTypeInfo(expression);
+        var expressionType = expressionTypeInfo.Type;
         if (expressionType == null)
         {
             return;
         }
 
-        var castType = context.SemanticModel.GetTypeInfo(type).Type;
+        var castTypeInfo = context.SemanticModel.GetTypeInfo(type);
+        var castType = castTypeInfo.Type;
         if (castType == null)
         {
             return;
         }
 
-        if (expression.Parent.Parent is AnonymousObjectMemberDeclaratorSyntax { Parent: AnonymousObjectCreationExpressionSyntax anon })
-        {
-            if (anon.Parent.Parent is ImplicitArrayCreationExpressionSyntax arrayCreation
-                && arrayCreation.Initializer.Expressions.Skip(1).Any())
-            {
-                return;
-            }
-            if (SwitchExpressionArmSyntaxWrapper.IsInstance(anon.Parent))
-            {
-                return;
-            }
-        }
-
-        if (expressionType.Equals(castType))
+        if (expressionType.Equals(castType) && expressionTypeInfo.Nullability() == castTypeInfo.Nullability())
         {
             ReportIssue(context, expression, location, castType);
         }

diff --git a/analyzers/tests/SonarAnalyzer.UnitTest/TestCases/RedundantCast.CSharp8.cs b/analyzers/tests/SonarAnalyzer.UnitTest/TestCases/RedundantCast.CSharp8.cs
@@ -1,16 +1,34 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-
 namespace Tests.Diagnostics
 {
     // https://github.com/SonarSource/sonar-dotnet/issues/3273
     public class CastOnNullable
     {
+#nullable enable
         public void Simple()
         {
-            var s1 = (string?)"Test";   // Noncompliant
-            var s2 = (string)s1!;       // Noncompliant
+            var nullable = (string?)"Test";         // Compliant
+            var nonNullable = (string)nullable!;    // Compliant
+            if (nullable != null)
+            {
+                var s1 = (string)nullable;          // Compliant
+                var s2 = (string?)nullable;         // Compliant
+            }
+            if (nonNullable != null)
+            {
+                var s1 = (string)nonNullable;       // Compliant
+                var s2 = (string?)nonNullable;      // Compliant
+            }
+        }
+
+        public void NonNullable()
+        {
+#nullable disable
+            var s1 = (string?)"Test";   // Compliant
+            var s2 = (string)s1!;       // Compliant
+#nullable enable
         }
 
         public static IEnumerable<string> UsefulCast()
@@ -25,14 +43,14 @@ public class AnonTypes
     {
         public void Simple()
         {
-            var anon = new { X = (string?)"foo" };  // Noncompliant
+            var anon = new { X = (string?)"foo" };  // Compliant
         }
 
         public void Array()
         {
             var anonArray = new[] { new { X = (string?)"foo" }, new { X = (string?)null } };    // Compliant
-            var oneElementAnonArray = new[] { new { X = (string?)"foo" } };                     // Noncompliant
-            var notSoAnonArray = new[] { new HoldsObject(new { X = (string?)"foo" }) };         // Noncompliant
+            var oneElementAnonArray = new[] { new { X = (string?)"foo" } };                     // Compliant
+            var notSoAnonArray = new[] { new HoldsObject(new { X = (string?)"foo" }) };         // Compliant
         }
 
         public void SwitchExpression()