[BUG] extensions method with long/double argument causes JNI error when run in Eclipse

[marc-guenther]

Describe the bug
An extension method with a long or double parameter, which is called with an int, causes an JNI error during runtime when loading the class.

Definition of the extension method with a long argument:

public static <T> void hello(String that, long n) {
    // nothing here
}

Calling it with an int:

public void someMethod() {
    "".hello(1);
}

This compiles, but when run in Eclipse, produces the JNI error below.

Calling with a long instead (eg. changing the 1 to a 1l) fixes the problem.

To Reproduce

See here for an example project:

• https://github.com/marc-guenther/lombok-problems

The problem can be seen in the JNIProblem.java class.

When launching the class in Eclipse, it will fail like this:

Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.VerifyError: Bad type on operand stack
Exception Details:
  Location:
    prob/lems/JNIProblem.someMethod()V @3: invokestatic
  Reason:
    Type integer (current frame, stack[1]) is not assignable to long_2nd
  Current Frame:
    bci: @3
    flags: { }
    locals: { 'prob/lems/JNIProblem' }
    stack: { 'java/lang/String', integer }
  Bytecode:
    0x0000000: 120f 08b8 0011 120f 1400 17b8 0011 b1  

	at java.lang.Class.getDeclaredMethods0(Native Method)
	at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
	at java.lang.Class.privateGetMethodRecursive(Class.java:3048)
	at java.lang.Class.getMethod0(Class.java:3018)
	at java.lang.Class.getMethod(Class.java:1784)
	at sun.launcher.LauncherHelper.validateMainClass(LauncherHelper.java:650)
	at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:632)

With javac/java it works just fine:

$ make jni_problem
javac -cp lombok-1.18.28.jar prob/lems/JNIProblem.java
java -cp lombok-1.18.28.jar:. 'prob.lems.JNIProblem'
works in javac but not with Eclipse

Expected behavior
No JNI error :)

Version info:

• Lombok version: 1.18.28
• Eclipse: 2022-03 (4.23.0)

Workaround

Define both versions of the extension method (int and long), and let one call the other.

When I tried this, it still wouldn't work. Turns out, Eclipse does not recompile my calling class, when the extension method class changes.

After a Clean Build everything worked fine.

[Rawi01]

Thanks for the detailed bug report. IIRC we already have some special handling for casts but it seems to be incomplete or incompatible with recent eclipse versions.

[marc-guenther]

I can confirm that this fixes the problem. Thanks a lot! Always nice to fix a bug by removing "magic" from the code :)