Change class loader in ir interpreter that is used to create proxy obj

#KT-54509 Fixed

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -17015,6 +17015,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/evaluate/simpleCallBinary.kt");
         }
 
+        @Test
+        @TestMetadata("thisPlusString.kt")
+        public void testThisPlusString() throws Exception {
+            runTest("compiler/testData/codegen/box/evaluate/thisPlusString.kt");
+        }
+
         @Test
         @TestMetadata("unaryMinus.kt")
         public void testUnaryMinus() throws Exception {

compiler/ir/ir.interpreter/src/org/jetbrains/kotlin/ir/interpreter/proxy/CommonProxy.kt

@@ -77,7 +77,7 @@ internal class CommonProxy private constructor(override val state: Common, overr
                 else -> arrayOf(extendFrom, Proxy::class.java)
             }
 
-            return java.lang.reflect.Proxy.newProxyInstance(ClassLoader.getSystemClassLoader(), interfaces)
+            return java.lang.reflect.Proxy.newProxyInstance(this::class.java.classLoader, interfaces)
             { /*proxy*/_, method, args ->
                 when {
                     method.declaringClass == Proxy::class.java && method.name == "getState" -> commonProxy.state

compiler/testData/codegen/box/evaluate/thisPlusString.kt

@@ -0,0 +1,17 @@
+// TARGET_BACKEND: JVM_IR
+// WITH_STDLIB
+
+object Test {
+    fun foo(): String = "foo " + this
+
+    fun bar(): String = "bar $this"
+
+    fun baz(): String = "baz " + this.toString()
+}
+
+fun box(): String {
+    if (!Test.foo().startsWith("foo ")) return "Fail ${Test.foo()}"
+    if (!Test.bar().startsWith("bar ")) return "Fail ${Test.bar()}"
+    if (!Test.baz().startsWith("baz ")) return "Fail ${Test.baz()}"
+    return "OK"
+}

compiler/testData/launcher/interpreterClassLoader.kt

@@ -0,0 +1,14 @@
+package test
+
+// for more information see KT-54509
+object Test {
+    fun foo(): String = "foo " + this
+
+    fun bar(): String = "bar $this"
+
+    fun baz(): String = "baz " + this.toString()
+}
+
+fun main() {
+    println(Test.foo() + Test.bar() + Test.baz())
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/codegen/IrBlackBoxCodegenTestGenerated.java

@@ -17015,6 +17015,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/evaluate/simpleCallBinary.kt");
         }
 
+        @Test
+        @TestMetadata("thisPlusString.kt")
+        public void testThisPlusString() throws Exception {
+            runTest("compiler/testData/codegen/box/evaluate/thisPlusString.kt");
+        }
+
         @Test
         @TestMetadata("unaryMinus.kt")
         public void testUnaryMinus() throws Exception {

compiler/tests/org/jetbrains/kotlin/cli/LauncherScriptTest.kt

@@ -472,4 +472,10 @@ println(42)
             environment = jdk11,
         )
     }
+
+    fun testInterpreterClassLoader() {
+        runProcess(
+            "kotlinc", "$testDataDirectory/interpreterClassLoader.kt", "-d", tmpdir.path
+        )
+    }
 }