ADDITIONAL SYSTEM INFORMATION :
```
OS:
Operating System Name: Windows 11
Operating System Architecture: amd64
Operating System Version: 10.0
```
OpenJDK version:
```
java version "1.8.0_451"
Java(TM) SE Runtime Environment (build 1.8.0_451-b10)
Java HotSpot(TM) 64-Bit Server VM (build 25.451-b10, mixed mode)
java version "11.0.27" 2025-04-15 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.27+8-LTS-232)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.27+8-LTS-232, mixed mode)
```
Output from `java -version`.
A DESCRIPTION OF THE PROBLEM :
Given a test case, we found that the execution results of this test case on different versions are different, the simplified test case can be found below. In summary, Hotspot(1.8.0_451) ran normally while Hotspot(11.0.27) threw IncompatibleClassChangeError.
STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Repoduce:
```
>>> path_to_jdk/hotspot/1.8.0_451/bin/java -cp . TestLauncher
>>> path_to_jdk/hotspot/11.0.27/bin/java -cp . TestLauncher
```
EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
According to this interesting result, we first decompiled TestLauncher using javap. The results are as follows:
```java
Classfile /xxx/TestLauncher.class
Last modified 2025年7月24日; size 536 bytes
MD5 checksum e4b325e8eeac8e5df91e606cc434ddc6
public class TestLauncher
minor version: 0
major version: 52
flags: (0x0021) ACC_PUBLIC, ACC_SUPER
this_class: #2 // TestLauncher
super_class: #4 // java/lang/Object
interfaces: 0, fields: 0, methods: 1, attributes: 0
Constant pool:
#1 = Utf8 TestLauncher
#2 = Class #1 // TestLauncher
#3 = Utf8 java/lang/Object
#4 = Class #3 // java/lang/Object
#5 = Utf8 main
#6 = Utf8 ([Ljava/lang/String;)V
#7 = Utf8 TestClass1
#8 = Class #7 // TestClass1
#9 = Utf8 run
#10 = Utf8 ()V
#11 = NameAndType #9:#10 // run:()V
#12 = Methodref #8.#11 // TestClass1.run:()V
#13 = Utf8 TestClass2
#14 = Class #13 // TestClass2
#15 = Methodref #14.#11 // TestClass2.run:()V
#16 = Utf8 InvalidTestClass
#17 = Class #16 // InvalidTestClass
#18 = Methodref #17.#11 // InvalidTestClass.run:()V
#19 = Utf8 java/lang/System
#20 = Class #19 // java/lang/System
#21 = Utf8 out
#22 = Utf8 Ljava/io/PrintStream;
#23 = NameAndType #21:#22 // out:Ljava/io/PrintStream;
#24 = Fieldref #20.#23 // java/lang/System.out:Ljava/io/PrintStream;
#25 = Utf8 InvalidTestClass load fail:
#26 = String #25 // InvalidTestClass load fail:
#27 = Utf8 java/io/PrintStream
#28 = Class #27 // java/io/PrintStream
#29 = Utf8 print
#30 = Utf8 (Ljava/lang/String;)V
#31 = NameAndType #29:#30 // print:(Ljava/lang/String;)V
#32 = Methodref #28.#31 // java/io/PrintStream.print:(Ljava/lang/String;)V
#33 = Utf8 java/lang/Throwable
#34 = Class #33 // java/lang/Throwable
#35 = Utf8 toString
#36 = Utf8 ()Ljava/lang/String;
#37 = NameAndType #35:#36 // toString:()Ljava/lang/String;
#38 = Methodref #34.#37 // java/lang/Throwable.toString:()Ljava/lang/String;
#39 = Utf8 println
#40 = NameAndType #39:#30 // println:(Ljava/lang/String;)V
#41 = Methodref #28.#40 // java/io/PrintStream.println:(Ljava/lang/String;)V
#42 = Utf8 Code
#43 = Utf8 StackMapTable
{
public static void main(java.lang.String[]);
descriptor: ([Ljava/lang/String;)V
flags: (0x0009) ACC_PUBLIC, ACC_STATIC
Code:
stack=2, locals=2, args_size=1
0: invokestatic #12 // Method TestClass1.run:()V
3: invokestatic #15 // Method TestClass2.run:()V
6: invokestatic #18 // Method InvalidTestClass.run:()V
9: goto 31
12: astore_1
13: getstatic #24 // Field java/lang/System.out:Ljava/io/PrintStream;
16: ldc #26 // String InvalidTestClass load fail:
18: invokevirtual #32 // Method java/io/PrintStream.print:(Ljava/lang/String;)V
21: getstatic #24 // Field java/lang/System.out:Ljava/io/PrintStream;
24: aload_1
25: invokevirtual #38 // Method java/lang/Throwable.toString:()Ljava/lang/String;
28: invokevirtual #41 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
31: return
Exception table:
from to target type
6 9 12 Class java/lang/Throwable
StackMapTable: number_of_entries = 2
frame_type = 76 /* same_locals_1_stack_item */
stack = [ class java/lang/Throwable ]
frame_type = 18 /* same */
}
```
We observed that for `TestLauncher.main`, the instruction `TestClass1.run();` uses `invokestatic`, while the resolved target is `TestClass1`, which is an interface. According to method resolution as specified in [JVM SE8 §6.5 invokestatic](https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-6.html#jvms-6.5.invokestatic), "The named method is resolved ([§5.4.3.3](https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-5.html#jvms-5.4.3.3))." Meanwhile, [chapter 5.4.3.3](https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-5.html#jvms-5.4.3.3) states, "1. If C is an interface, method resolution throws an `IncompatibleClassChangeError`." Therefore, for hotspot (1.8.451), an `IncompatibleClassChangeError` should be thrown, rather than the method running normally.
Similarly, due to [JVM SE11 §6.5 invokestatic](https://docs.oracle.com/javase/specs/jvms/se11/html/jvms-6.html#jvms-6.5.invokeinterface), which states, "The named method is resolved ([§5.4.3.3](https://docs.oracle.com/javase/specs/jvms/se11/html/jvms-5.html#jvms-5.4.3.3), [§5.4.3.4](https://docs.oracle.com/javase/specs/jvms/se11/html/jvms-5.html#jvms-5.4.3.4)),” allowing resolution of methods on interfaces, for hotspot(11.0.27) the test case should execute normally instead of throwing an `IncompatibleClassChangeError`.
ACTUAL -
The output is as follows:
hotspot(1.8.0_451):
```
TestClass1 correctly overrides conflicting methods.
TestClass2 does not override conflicting methods.
InvalidTestClass should throw an error for conflicting methods.
```
hotspot(11.0.27):
```
Exception in thread "main" java.lang.IncompatibleClassChangeError: Method 'void TestClass1.run()' must be InterfaceMethodref constant
at TestLauncher.main(Unknown Source)
```
---------- BEGIN SOURCE ----------
The following code can be used to generate the test cases(.class file) that reproduces the above process:
```java
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
public class BytecodeUtil {
public static void main(String args[]) {
// create package
String baseDir = "./your_dir"; // your base dir
File baseDirFile = new File(baseDir);
baseDirFile.mkdirs();
String interface1_bytecodeInStr = "CAFEBABE00000034000701000A496E74657266616365310700010100106A6176612F6C616E672F4F626A6563740700030100076D6574686F643101000328295606010002000400000000000104010005000600000000" ;
String interface2_bytecodeInStr = "CAFEBABE00000034000701000A496E74657266616365320700010100106A6176612F6C616E672F4F626A6563740700030100076D6574686F643201000328295606010002000400000000000104010005000600000000" ;
String interface3_bytecodeInStr = "CAFEBABE00000034000701000A496E74657266616365330700010100106A6176612F6C616E672F4F626A6563740700030100076D6574686F643101000328295606010002000400000000000104010005000600000000" ;
String InvalidTestClass_bytecodeInStr = "CAFEBABE00000034001F010010496E76616C696454657374436C6173730700010100106A6176612F6C616E672F4F626A65637407000301000A496E746572666163653107000501000A496E746572666163653207000701000A496E74657266616365330700090100076D6574686F64310100032829560100076D6574686F64320100042849295601000372756E0100106A6176612F6C616E672F53797374656D0700100100036F75740100154C6A6176612F696F2F5072696E7453747265616D3B0C00120013090011001401003F496E76616C696454657374436C6173732073686F756C64207468726F7720616E206572726F7220666F7220636F6E666C696374696E67206D6574686F64732E0800160100136A6176612F696F2F5072696E7453747265616D0700180100077072696E746C6E010015284C6A6176612F6C616E672F537472696E673B29560C001A001B0A0019001C010004436F6465060100020004000300060008000A000000040401000B000C00000401000D000C00000401000B000E00000009000F000C0001001E000000150002000000000009B200151217B6001DB1000000000000" ;
String TestClass1_bytecodeInStr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
String TestClass2_bytecodeInStr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
String TestLauncher_bytecodeInStr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
try (FileOutputStream fos = new FileOutputStream(baseDir + "/" + "interface1.class")) {
byte[] interface1_bytecode = hexStringToByteArray(interface1_bytecodeInStr);
fos.write(interface1_bytecode);
} catch (IOException e) {
e.printStackTrace();
}
try (FileOutputStream fos = new FileOutputStream(baseDir + "/" + "interface2.class")) {
byte[] interface2_bytecode = hexStringToByteArray(interface2_bytecodeInStr);
fos.write(interface2_bytecode);
} catch (IOException e) {
e.printStackTrace();
}
try (FileOutputStream fos = new FileOutputStream(baseDir + "/" + "interface3.class")) {
byte[] interface3_bytecode = hexStringToByteArray(interface3_bytecodeInStr);
fos.write(interface3_bytecode);
} catch (IOException e) {
e.printStackTrace();
}
try (FileOutputStream fos = new FileOutputStream(baseDir + "/" + "InvalidTestClass.class")) {
byte[] InvalidTestClass_bytecode = hexStringToByteArray(InvalidTestClass_bytecodeInStr);
fos.write(InvalidTestClass_bytecode);
} catch (IOException e) {
e.printStackTrace();
}
try (FileOutputStream fos = new FileOutputStream(baseDir + "/" + "TestClass1.class")) {
byte[] TestClass1_bytecode = hexStringToByteArray(TestClass1_bytecodeInStr);
fos.write(TestClass1_bytecode);
} catch (IOException e) {
e.printStackTrace();
}
try (FileOutputStream fos = new FileOutputStream(baseDir + "/" + "TestClass2.class")) {
byte[] TestClass2_bytecode = hexStringToByteArray(TestClass2_bytecodeInStr);
fos.write(TestClass2_bytecode);
} catch (IOException e) {
e.printStackTrace();
}
try (FileOutputStream fos = new FileOutputStream(baseDir + "/" + "TestLauncher.class")) {
byte[] TestLauncher_bytecode = hexStringToByteArray(TestLauncher_bytecodeInStr);
fos.write(TestLauncher_bytecode);
} catch (IOException e) {
e.printStackTrace();
}
}
public static byte[] hexStringToByteArray(String hexString) {
int length = hexString.length();
byte[] byteArray = new byte[length / 2];
for (int i = 0; i < length; i += 2) {
int byteValue = Integer.parseInt(hexString.substring(i, i + 2), 16);
byteArray[i / 2] = (byte) byteValue;
}
return byteArray;
}
}
```
Note: modify the paths according to your needs.
After obtaining the test cases, you can derive the following test cases through decompilation:
```java
public interface Interface1 {
void method1();
}
```
```java
public interface Interface2 {
void method2();
}
```
```java
public interface Interface3 {
void method1();
}
```
```java
public interface InvalidTestClass extends Interface1, Interface2, Interface3 {
void method1();
void method2();
void method1(int var1);
static void run() {
System.out.println("InvalidTestClass should throw an error for conflicting methods.");
}
}
```
```java
public interface TestClass1 extends Interface1, Interface2, Interface3 {
void method1();
void method2();
static void run() {
System.out.println("TestClass1 correctly overrides conflicting methods.");
}
}
```
```java
public interface TestClass2 extends Interface1, Interface2, Interface3 {
static void run() {
System.out.println("TestClass2 does not override conflicting methods.");
}
}
```
```java
public class TestLauncher {
public static void main(String[] var0) {
TestClass1.run();
TestClass2.run();
try {
InvalidTestClass.run();
} catch (Throwable var2) {
System.out.print("InvalidTestClass load fail: ");
System.out.println(var2.toString());
}
}
}
```
---------- END SOURCE ----------