Fix warnings in stdlib/compiler/plugins/test code

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/backend/handlers/JvmBoxRunner.kt

@@ -86,13 +86,13 @@ class JvmBoxRunner(testServices: TestServices) : JvmBinaryArtifactHandler(testSe
 
     private fun callBoxMethodAndCheckResult(
         classLoader: URLClassLoader,
-        clazz: Class<*>?,
+        @Suppress("UNUSED_PARAMETER") clazz: Class<*>?,
         method: Method,
         unexpectedBehaviour: Boolean
     ) {
         val result = if (BOX_IN_SEPARATE_PROCESS_PORT != null) {
             TODO()
-//            result = invokeBoxInSeparateProcess(classLoader, aClass)
+//            result = invokeBoxInSeparateProcess(classLoader, clazz)
         } else {
             val savedClassLoader = Thread.currentThread().contextClassLoader
             if (savedClassLoader !== classLoader) {

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/frontend/classic/ClassicFrontend2IrConverter.kt

@@ -30,7 +30,7 @@ class ClassicFrontend2IrConverter(
         module: TestModule,
         inputArtifact: ClassicFrontendOutputArtifact
     ): IrBackendInput {
-        val (psiFiles, analysisResult, project, languageVersionSettings) = inputArtifact
+        val (psiFiles, analysisResult, project, _) = inputArtifact
 
         val configuration = testServices.compilerConfigurationProvider.getCompilerConfiguration(module)
 

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/frontend/fir/handlers/FirDiagnosticCodeMetaInfo.kt

@@ -73,6 +73,7 @@ class FirDiagnosticCodeMetaRenderConfiguration(
 
         val diagnostic = codeMetaInfo.diagnostic
 
+        @Suppress("UNCHECKED_CAST")
         val renderer = FirDefaultErrorMessages.getRendererForDiagnostic(diagnostic) as FirDiagnosticRenderer<FirDiagnostic<*>>
         params.add(renderer.render(diagnostic))