Dependency do not support constant

[GeeJoe]

I tried to scan a class's dependency using JavaClass.directDependenciesToSelf but I found the constant in the class which is using by another class was not in the dependency list.

What should I do?

[hankem]

I believe that the statement from #298 (comment) is unfortunately still true:

there is at the moment no workaround with ArchUnit to detect a dependency that is only observable through the constant pool.

Somebody needs to find some time to implement #309.

[codecholeric]

I just played around a little and I think it will work to inspect ldc instructions with the current ASM version 😃 I'll see if I can find some time the next days to implement this!

[GeeJoe]

I just played around a little and I think it will work to inspect ldc instructions with the current ASM version 😃 I'll see if I can find some time the next days to implement this!

Did you resolve this issue? I find the problem still exist in com.tngtech.archunit:archunit:0.17.0

[codecholeric]

Are you sure? Can you show me an example? AFAIS something like this should now be detected, right?

class One {
    private Class<?> causesDependency = Two.class;
}

class Two {
}

What is your concrete case?

[GeeJoe]

Like

class One {
    public static final String TAG = "Hello";
}

class Two {
     private String tag = One.TAG;
}

If I try to get getDirectDependenciesFromSlef() on class Two，the result won't contain class One

[hankem]

There is some confusion: Since ArchUnit 0.16.0, JavaClass/JavaCodeUnit know their references to other class objects (like Two.class in the example above), but primitive constants (like your String TAG) have a different signature in the bytecode (see also #298).

The bytecode for your example

class Two
  minor version: 0
  major version: 55
  flags: (0x0020) ACC_SUPER
  this_class: #5                          // Two
  super_class: #6                         // java/lang/Object
  interfaces: 0, fields: 1, methods: 1, attributes: 1
Constant pool:
   #1 = Methodref          #6.#15         // java/lang/Object."<init>":()V
   #2 = Class              #16            // One
   #3 = String             #17            // Hello
   #4 = Fieldref           #5.#18         // Two.tag:Ljava/lang/String;
   #5 = Class              #19            // Two
   #6 = Class              #20            // java/lang/Object
   #7 = Utf8               tag
   #8 = Utf8               Ljava/lang/String;
   #9 = Utf8               <init>
  #10 = Utf8               ()V
  #11 = Utf8               Code
  #12 = Utf8               LineNumberTable
  #13 = Utf8               SourceFile
  #14 = Utf8               OneAndTwo.java
  #15 = NameAndType        #9:#10         // "<init>":()V
  #16 = Utf8               One
  #17 = Utf8               Hello
  #18 = NameAndType        #7:#8          // tag:Ljava/lang/String;
  #19 = Utf8               Two
  #20 = Utf8               java/lang/Object
{
  private java.lang.String tag;
    descriptor: Ljava/lang/String;
    flags: (0x0002) ACC_PRIVATE

  Two();
    descriptor: ()V
    flags: (0x0000)
    Code:
      stack=2, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."<init>":()V
         4: aload_0
         5: ldc           #3                  // String Hello
         7: putfield      #4                  // Field tag:Ljava/lang/String;
        10: return
}

initializes Two.tag from the result of a ldc #3 instruction to load a constant that is actually copied into Two's own pool:

   #3 = String             #17            // Hello
  // ...
  #17 = Utf8               Hello

That's why the usage of the primitive constant One.TAG is currently not recognized as a dependency.

[GeeJoe]

Thanks for your detailed explanation! Hope that you can implement this soon. :)