use MainFunctionDetector in order to check for main function

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

@@ -27,12 +27,12 @@ import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor.Kind.FAKE_OVERR
 import org.jetbrains.kotlin.diagnostics.DiagnosticSink
 import org.jetbrains.kotlin.fileClasses.JvmFileClassesProvider
 import org.jetbrains.kotlin.fileClasses.isInsideJvmMultifileClassFile
+import org.jetbrains.kotlin.idea.MainFunctionDetector
 import org.jetbrains.kotlin.load.java.descriptors.SamAdapterDescriptor
 import org.jetbrains.kotlin.load.kotlin.incremental.components.IncrementalCache
-import org.jetbrains.kotlin.psi.JetDeclaration
+import org.jetbrains.kotlin.psi.JetNamedFunction
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.DescriptorToSourceUtils
-import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.jvm.diagnostics.*
 import org.jetbrains.kotlin.utils.addIfNotNull
 import java.util.*
@@ -54,6 +54,8 @@ class BuilderFactoryForDuplicateSignatureDiagnostics(
     // Avoid errors when some classes are not loaded for some reason
     private val typeMapper = JetTypeMapper(bindingContext, ClassBuilderMode.LIGHT_CLASSES, fileClassesProvider, incrementalCache, moduleName)
 
+    private val mainFunctionDetector = MainFunctionDetector(bindingContext)
+
     override fun handleClashingSignatures(data: ConflictingJvmDeclarationsData) {
         val noOwnImplementations = data.signatureOrigins.all { it.originKind in EXTERNAL_SOURCES_KINDS }
 
@@ -66,11 +68,7 @@ class BuilderFactoryForDuplicateSignatureDiagnostics(
                 var element = origin.element
 
                 // TODO Remove this code after dropping package facades
-                val descriptor = origin.descriptor
-                if (descriptor != null && element is JetDeclaration && DescriptorUtils.isTopLevelMainFunction(descriptor) &&
-                        !element.isInsideJvmMultifileClassFile()) {
-                    return
-                }
+                if (element is JetNamedFunction && mainFunctionDetector.isMain(element) && !element.isInsideJvmMultifileClassFile()) return
 
                 if (element == null || origin.originKind in EXTERNAL_SOURCES_KINDS) {
                     element = data.classOrigin.element