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Interesting bug of intellij decompiler

Strange char

When I view the source of a project, I notice it use log4j. So, I click into the logger.error method, and intellij decompile the class file and show the following code:
public void error(Object message, Throwable t) {
    if(!this.repository.isDisabled('鱀')) {//<--here
        if(Level.ERROR.isGreaterOrEqual(this.getEffectiveLevel())) {
            this.forcedLog(FQCN, Level.ERROR, message, t);
        }
    }
}
I was attracted by that strange character, because this character is so rare, so who would use such char in the code? There must be some reason.

Real source

It is strange, right? I am curious about that strange character so I find the source as following:
void error(Object message, Throwable t) {
  if(repository.isDisabled(Level.ERROR_INT))
    return;
  if(Level.ERROR.isGreaterOrEqual(this.getEffectiveLevel()))
    forcedLog(FQCN, Level.ERROR, message, t);
}

// Level.ERROR_INT
public final static int ERROR_INT = 40000;
Now, we understand it. When intellij decompile the class, it convert the int 40000 to a char(which has a range of 0-65535).

Verify

But it may be the java compiler who see it is a int can represented by a char and change it. So I decompile the class file use javap to see whether it is represented by a char or int.
javap -c Category.class
  public void error(java.lang.Object, java.lang.Throwable);
    Code:
       0: aload_0
       1: getfield      #13                 // Field repository:Lorg/apache/log4j/spi/LoggerRepository;
       4: ldc           #31                 // int 40000
       6: invokeinterface #25,  2           // InterfaceMethod org/apache/log4j/spi/LoggerRepository.isDisabled:(I)Z
      11: ifeq          15

// ldc means: push a constant #index from a constant pool (String, int or float) onto the stack
From the line 4, we can see it indeed a int, so it is some kind of bug.

char to int

Actually, when I write a large unicode char in source code, java compiler will automatically change it to a int
  final char c2 = '鱀';
  System.out.println(c2);
  System.out.println('c');

  125: ldc           #19                 // int 40000 -- here
  127: istore        5
  129: getstatic     #5                  // Field java/lang/System.out:Ljava/io/PrintStream;
  132: ldc           #19                 // int 40000 -- and here
  134: invokevirtual #20                 // Method java/io/PrintStream.println:(C)V
  137: getstatic     #5                  // Field java/lang/System.out:Ljava/io/PrintStream;
  140: bipush        99
  142: invokevirtual #20                 // Method java/io/PrintStream.println:(C)V
A simple code snippet can be get from here

Ref

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