Why is an in used function still shown in usage.txt of proguard output?

Question

I have the following code

class MainActivity : AppCompatActivity() {
    private val obfuscatedClass = MyObfuscatedClass()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        obfuscatedClass.usedFunc()
    }
}

class MyObfuscatedClass {
    fun usedFunc() {}
    fun unusedFunc() {}
}

With a normal proguard, I generate the usage.txt file, showing the unusedFunc() there

com.example.myobfuscateretracetest.MyObfuscatedClass:
    public final void unusedFunc()

This is correct, as the usage.txt file is meant to show the class or removed function during compilation as mentioned in

However, if I change my class to a lazy as shown below,

class MainActivity : AppCompatActivity() {
    private val obfuscatedClass by lazy {
        MyObfuscatedClass()
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        obfuscatedClass.usedFunc()
    }
}

class MyObfuscatedClass {
    fun usedFunc() {}
    fun unusedFunc() {}
}

When I check the usage.txt, I notice that both also shown, just in a different section

com.example.myobfuscateretracetest.MyObfuscatedClass:
    public final void unusedFunc()

// ... other sections

com.example.myobfuscateretracetest.MyObfuscatedClass:
    public final void usedFunc()

Why is the usedFunc() still being shown in the usage.txt?

score 0 · Accepted Answer · answered May 09 '22 at 13:59

Apparently the odd behavior of scenario 2 above only happen when using

buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
    }
}

If I use the non-optimize default proguard, then it's alright.

buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

Perhaps the optimize proguard does more advanced optimization, though the function is used, but it still got optimized away?

Why is an in used function still shown in usage.txt of proguard output?

1 Answers1