Fix RCS0034

ChangeLog.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Fix analyzer [RCS0034](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS0034) ([PR](https://github.com/dotnet/roslynator/pull/1351))
+
 ## [4.8.0] - 2024-01-02
 
 ### Added

src/Formatting.Analyzers/CSharp/PutTypeParameterConstraintOnItsOwnLineAnalyzer.cs

@@ -47,12 +47,16 @@ private static void AnalyzeTypeDeclaration(SyntaxNodeAnalysisContext context)
 
         SyntaxList<TypeParameterConstraintClauseSyntax> constraintClauses = typeDeclaration.ConstraintClauses;
 
-        TypeParameterListSyntax typeParameterList = typeDeclaration.TypeParameterList;
+        BaseTypeSyntax baseType = typeDeclaration.BaseList?.Types.LastOrDefault();
 
-        if (typeParameterList is null)
-            return;
-
-        Analyze(context, typeParameterList.GreaterThanToken, constraintClauses);
+        if (baseType is not null)
+        {
+            Analyze(context, baseType, constraintClauses);
+        }
+        else if (typeDeclaration.TypeParameterList is not null)
+        {
+            Analyze(context, typeDeclaration.TypeParameterList.GreaterThanToken, constraintClauses);
+        }
     }
 
     private static void AnalyzeDelegateDeclaration(SyntaxNodeAnalysisContext context)

src/Tests/Formatting.Analyzers.Tests/RCS0034PutTypeParameterConstraintOnItsOwnLineTests.cs

@@ -167,4 +167,23 @@ class C<T> where T : struct
 }
 ");
     }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.PutTypeParameterConstraintOnItsOwnLine)]
+    public async Task TestNoDiagnostic_BaseType()
+    {
+        await VerifyNoDiagnosticAsync(@"
+using System;
+
+public interface IBaseInterface<TType, TKey>
+    where TType : class
+    where TKey : struct, IEquatable<TKey>
+{
+}
+
+public interface IInterface<TType, TKey> : IBaseInterface<TType, TKey>
+    where TType : class
+    where TKey : struct, IEquatable<TKey>
+{
+}");
+    }
 }