[JS IR BE] Don't transform toString with extension receiver

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/calls/MethodsOfAnyCallsTransformer.kt

@@ -64,20 +64,17 @@ class MethodsOfAnyCallsTransformer(context: JsIrBackendContext) : CallsTransform
     }
 
     private fun shouldReplaceToStringWithRuntimeCall(call: IrFunctionAccessExpression): Boolean {
-        // TODO: (KOTLIN-CR-2079)
-        //  - User defined extension functions Any?.toString() call can be lost during lowering.
-        //  - Use direct method call for dynamic types???
-        //  - Define Any?.toString() in runtime library and stop intrinsicifying extensions
-
-        if (call.valueArgumentsCount > 0)
+        val function = call.symbol.owner
+        if (function.valueParameters.size != 0 && function.name.asString() != "toString" )
             return false
 
-        val receiverParameterType = with(call.symbol.owner) {
-            dispatchReceiverParameter ?: extensionReceiverParameter
-        }?.type ?: return false
+        if (function.extensionReceiverParameter != null)
+            return false
+
+        val receiverParameterType = function.dispatchReceiverParameter?.type ?: return false
 
         return receiverParameterType.run {
-            isArray() || isAny() || isNullable() || this is IrDynamicType || isString()
+            isArray() || isAny() || this is IrDynamicType || isString()
         }
     }
 }

js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrBoxJsTestGenerated.java

@@ -6805,6 +6805,11 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             public void testTaggedArrayCopy() throws Exception {
                 runTest("js/js.translator/testData/box/regression/typeChecks/taggedArrayCopy.kt");
             }
+
+            @TestMetadata("toStringExtension.kt")
+            public void testToStringExtension() throws Exception {
+                runTest("js/js.translator/testData/box/regression/typeChecks/toStringExtension.kt");
+            }
         }
     }
 

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java

@@ -6840,6 +6840,11 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             public void testTaggedArrayCopy() throws Exception {
                 runTest("js/js.translator/testData/box/regression/typeChecks/taggedArrayCopy.kt");
             }
+
+            @TestMetadata("toStringExtension.kt")
+            public void testToStringExtension() throws Exception {
+                runTest("js/js.translator/testData/box/regression/typeChecks/toStringExtension.kt");
+            }
         }
     }
 

js/js.translator/testData/box/regression/typeChecks/toStringExtension.kt

@@ -0,0 +1,9 @@
+// EXPECTED_REACHABLE_NODES: 1281
+
+package foo
+
+class A
+
+fun A?.toString() = "OK"
+
+fun box() = (null as A?).toString()