K2: report DUPLICATE_CLASS_NAMES error in JVM backend

It was already reported in the K2+PSI mode, but not LT because
BuilderFactoryForDuplicateClassNameDiagnostics relied on PSI, and did
not do anything if PSI was missing.

No tests were added because it fixes the already existing test
`compiler/testData/cli/jvm/fileClassClashMultipleFiles` after the
project is migrated to 2.0.

 #KT-59586

compiler/backend/src/org/jetbrains/kotlin/codegen/state/BuilderFactoryForDuplicateClassNameDiagnostics.kt

@@ -18,34 +18,33 @@ package org.jetbrains.kotlin.codegen.state
 
 import org.jetbrains.kotlin.codegen.ClassBuilderFactory
 import org.jetbrains.kotlin.codegen.ClassNameCollectionClassBuilderFactory
-import org.jetbrains.kotlin.diagnostics.DiagnosticSink
 import org.jetbrains.kotlin.renderer.DescriptorRenderer
-import org.jetbrains.kotlin.resolve.jvm.diagnostics.ErrorsJvm
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.JvmDeclarationOrigin
 import java.util.concurrent.ConcurrentHashMap
 
-
 class BuilderFactoryForDuplicateClassNameDiagnostics(
-        builderFactory: ClassBuilderFactory,
-        private val diagnostics: DiagnosticSink
+    builderFactory: ClassBuilderFactory,
+    private val state: GenerationState,
 ) : ClassNameCollectionClassBuilderFactory(builderFactory) {
 
     private val className = ConcurrentHashMap<String, JvmDeclarationOrigin>()
 
     override fun handleClashingNames(internalName: String, origin: JvmDeclarationOrigin) {
-        val another = className.getOrPut(internalName, { origin })
-        //workaround for inlined anonymous objects
-        if (origin.element != another.element) {
+        val another = className.getOrPut(internalName) { origin }
+        // Allow clashing classes if they are originated from the same source element. For example, this happens during inlining anonymous
+        // objects. In JVM IR, this also happens for anonymous classes in default arguments of tailrec functions, because default arguments
+        // are deep-copied (see JvmTailrecLowering).
+        if (origin.originalSourceElement != another.originalSourceElement) {
             reportError(internalName, origin, another)
         }
     }
 
     private fun reportError(internalName: String, vararg another: JvmDeclarationOrigin) {
-        val fromString = another.mapNotNull { it.descriptor }.
-                joinToString { DescriptorRenderer.ONLY_NAMES_WITH_SHORT_TYPES.render(it) }
+        val duplicateClasses =
+            another.mapNotNull { it.descriptor }.joinToString { DescriptorRenderer.ONLY_NAMES_WITH_SHORT_TYPES.render(it) }
 
-        another.mapNotNull { it.element }.forEach {
-            diagnostics.report(ErrorsJvm.DUPLICATE_CLASS_NAMES.on(it, internalName, fromString))
+        for (origin in another) {
+            state.reportDuplicateClassNameError(origin, internalName, duplicateClasses)
         }
     }
-}
+}

compiler/backend/src/org/jetbrains/kotlin/codegen/state/GenerationState.kt

@@ -46,6 +46,7 @@ import org.jetbrains.kotlin.resolve.diagnostics.Diagnostics
 import org.jetbrains.kotlin.resolve.diagnostics.OnDemandSuppressCache
 import org.jetbrains.kotlin.resolve.jvm.JvmClassName
 import org.jetbrains.kotlin.resolve.jvm.JvmCompilerDeserializationConfiguration
+import org.jetbrains.kotlin.resolve.jvm.diagnostics.ErrorsJvm
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.JvmDeclarationOrigin
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.JvmDeclarationOriginKind.*
 import org.jetbrains.kotlin.serialization.deserialization.DeserializationConfiguration
@@ -291,6 +292,12 @@ class GenerationState private constructor(
 
     var multiFieldValueClassUnboxInfo: (ClassDescriptor) -> MultiFieldValueClassUnboxInfo? = { null }
 
+    var reportDuplicateClassNameError: (JvmDeclarationOrigin, String, String) -> Unit = { origin, internalName, duplicateClasses ->
+        origin.element?.let {
+            diagnostics.report(ErrorsJvm.DUPLICATE_CLASS_NAMES.on(it, internalName, duplicateClasses))
+        }
+    }
+
     val typeApproximator: TypeApproximator? =
         if (languageVersionSettings.supportsFeature(LanguageFeature.NewInference))
             TypeApproximator(module.builtIns, languageVersionSettings)
@@ -308,7 +315,7 @@ class GenerationState private constructor(
                 },
                 {
                     // In IR backend, we have more precise information about classes and methods we are going to generate,
-                    // and report signature conflict errors in JvmSignatureClashTracker.
+                    // and report signature conflict errors in JvmSignatureClashDetector.
                     if (isIrBackend)
                         it
                     else
@@ -318,7 +325,7 @@ class GenerationState private constructor(
                             shouldGenerate = { origin -> !shouldOnlyCollectSignatures(origin) },
                         ).apply { duplicateSignatureFactory = this }
                 },
-                { BuilderFactoryForDuplicateClassNameDiagnostics(it, diagnostics) },
+                { BuilderFactoryForDuplicateClassNameDiagnostics(it, this) },
                 {
                     configuration.get(JVMConfigurationKeys.DECLARATIONS_JSON_PATH)
                         ?.let { destination -> SignatureDumpingBuilderFactory(it, File(destination)) } ?: it