Fix RCS1244 (#1007)

Author: josefpihrt

ChangeLog.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Fix [RCS1084](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1084.md) ([#1006](https://github.com/josefpihrt/roslynator/pull/1006)).
+- Fix [RCS1244](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1244.md) ([#1007](https://github.com/josefpihrt/roslynator/pull/1007)).
 
 ## [4.2.0] - 2022-11-27
 

src/Analyzers/CSharp/Analysis/DefaultExpressionAnalyzer.cs

@@ -107,6 +107,12 @@ public static void AnalyzeDefaultExpression(SyntaxNodeAnalysisContext context)
                     if (parent.IsParentKind(SyntaxKind.ObjectInitializerExpression))
                         return;
 
+                    if (parent is BinaryExpressionSyntax coalesceExpression
+                        && coalesceExpression.Left == defaultExpression)
+                    {
+                        return;
+                    }
+
                     TypeInfo typeInfo = context.SemanticModel.GetTypeInfo(expression, context.CancellationToken);
 
                     if (!SymbolEqualityComparer.Default.Equals(typeInfo.Type, typeInfo.ConvertedType))

src/Tests/Analyzers.Tests/RCS1244SimplifyDefaultExpressionTests.cs

@@ -490,6 +490,22 @@ void M()
         };
     }
 }
+");
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.SimplifyDefaultExpression)]
+    public async Task TestNoDiagnostic_LambdaExpression2()
+    {
+        await VerifyNoDiagnosticAsync(@"
+using System;
+
+class C
+{
+    T M<T>()
+    {
+        return default(T) ?? (T)Convert.ChangeType("""", typeof(T));
+    }
+}
 ");
     }
 }