JVM_IR indy: fix non-null assertions on indy lambda parameters

KT-44278 KT-26060 KT-42621

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt

@@ -275,7 +275,7 @@ class ExpressionCodegen(
             return
 
         if (inlinedInto != null ||
-            (DescriptorVisibilities.isPrivate(irFunction.visibility) && !(irFunction is IrSimpleFunction && irFunction.isOperator)) ||
+            (DescriptorVisibilities.isPrivate(irFunction.visibility) && !shouldGenerateNonNullAssertionsForPrivateFun(irFunction)) ||
             irFunction.origin.isSynthetic ||
             // TODO: refine this condition to not generate nullability assertions on parameters
             //       corresponding to captured variables and anonymous object super constructor arguments
@@ -310,6 +310,13 @@ class ExpressionCodegen(
         }
     }
 
+    // * Operator functions require non-null assertions on parameters even if they are private.
+    // * Local function for lambda survives at this stage if it was used in 'invokedynamic'-based code.
+    //   Such functions require non-null assertions on parameters.
+    private fun shouldGenerateNonNullAssertionsForPrivateFun(irFunction: IrFunction) =
+        irFunction is IrSimpleFunction && irFunction.isOperator ||
+                irFunction.origin == IrDeclarationOrigin.LOCAL_FUNCTION_FOR_LAMBDA
+
     private fun generateNonNullAssertion(param: IrValueParameter) {
         val asmType = param.type.asmType
         if (!param.type.unboxInlineClass().isNullable() && !isPrimitive(asmType)) {