New J2K: convert vararg type parameter Java length call to Kotlin size call

nj2k/src/org/jetbrains/kotlin/nj2k/conversions/ArrayOperationsConversion.kt

@@ -13,14 +13,15 @@ package org.jetbrains.kotlin.nj2k.conversions
 import org.jetbrains.kotlin.nj2k.NewJ2kConverterContext
 import org.jetbrains.kotlin.nj2k.tree.*
 import org.jetbrains.kotlin.nj2k.tree.impl.JKFieldAccessExpressionImpl
+import org.jetbrains.kotlin.nj2k.tree.impl.JKUniverseFieldSymbol
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 
 class ArrayOperationsConversion(private val context: NewJ2kConverterContext) : RecursiveApplicableConversionBase() {
     override fun applyToElement(element: JKTreeElement): JKTreeElement {
         if (element !is JKQualifiedExpression) return recurse(element)
         val selector = element.selector as? JKFieldAccessExpression ?: return recurse(element)
-        if (element.receiver.type(context.symbolProvider) !is JKJavaArrayType) return recurse(element)
-        if (selector.identifier.name == "length") {
+        if (element.receiver.isArrayOrVarargTypeParameter() && selector.identifier.name == "length") {
             val sizeCall =
                 JKFieldAccessExpressionImpl(
                     context.symbolProvider.provideFieldSymbol("kotlin.Array.size")
@@ -29,4 +30,15 @@ class ArrayOperationsConversion(private val context: NewJ2kConverterContext) : R
         }
         return recurse(element)
     }
+
+    private fun JKExpression.isArrayOrVarargTypeParameter(): Boolean {
+        if (type(context.symbolProvider) is JKJavaArrayType) return true
+        val parameter =
+            safeAs<JKFieldAccessExpression>()
+                ?.identifier
+                .safeAs<JKUniverseFieldSymbol>()
+                ?.target
+                ?.safeAs<JKParameter>()
+        return parameter?.isVarArgs == true
+    }
 }

nj2k/testData/newJ2k/varArg/varargLengthAccess.java

@@ -0,0 +1,4 @@
+//method
+int nya(Object... objs) {
+    return objs.length;
+}

nj2k/testData/newJ2k/varArg/varargLengthAccess.kt

@@ -0,0 +1,3 @@
+fun nya(vararg objs: Any?): Int {
+    return objs.size
+}

nj2k/tests/org/jetbrains/kotlin/nj2k/NewJavaToKotlinConverterSingleFileTestGenerated.java

@@ -4744,6 +4744,11 @@ public class NewJavaToKotlinConverterSingleFileTestGenerated extends AbstractNew
         public void testEllipsisTypeSingleParams() throws Exception {
             runTest("nj2k/testData/newJ2k/varArg/ellipsisTypeSingleParams.java");
         }
+
+        @TestMetadata("varargLengthAccess.java")
+        public void testVarargLengthAccess() throws Exception {
+            runTest("nj2k/testData/newJ2k/varArg/varargLengthAccess.java");
+        }
     }
 
     @TestMetadata("nj2k/testData/newJ2k/whileStatement")