[lint] DiffUtilEquals false positive when type is exactly known [161584622]

Fixed

Bug

Status Update

No update yet.

Description

pa...@gmail.com

created issue #1

Jul 20, 2020 02:15PM

Component: Android Public Tracker > App Development > Android Studio > Build Tools > Lint

Studio Build: irrelevant (4.0.1)

Version of Gradle Plugin: 3.6.3 or 4.0.1

Version of Gradle: irrelevant (5.6.4 or 6.5, whichever works with AGP version)

Version of Java: irrelevant (openjdk 1.8.0_242-release)

OS: irrelevant (Windows 10)

Steps to Reproduce:

Download DiffUtilEquals.zip
Extract it somewhere
Run gradlew lint in that folder

Expected: no lint violations Actual: 2 errors (1 in Java and 1 in Kotlin)

  Errors found:

  C:\dev\DiffUtilEquals\src\main\java\com\example\MyDiffUtilCallbackJava.java:18: Error: Suspicious equality check: equals() is not implemented in com.example.IModel [DiffUtilEquals]
     return oldItem.equals(newItem);
                    ~~~~~~~~~~~~~~~
  C:\dev\DiffUtilEquals\src\main\java\com\example\MyDiffUtilCallbackKotlin.kt:17: Error: Suspicious equality check: equals() is not implemented in IModel [DiffUtilEquals]
          oldItem is Model && newItem is Model && oldItem == newItem
                                                          ~~

Despite having a workaround in https://issuetracker.google.com/issues/122928037, we think that DiffUtilEquals should not trigger in these cases:

// Kotlin
oldItem is Model && newItem is Model && oldItem == newItem

// Java
if (oldItem instanceof Model && newItem instanceof Model) {
	return oldItem.equals(newItem);
}

iff Model class has a defined equals method.

This should be especially true in Kotlin where smart casts exist.

DiffUtilEquals.zip

57 KB

Download

Comments

uc...@google.com <uc...@google.com> Jul 20, 2020 05:08PM

Assigned to an...@google.com.

tn...@google.com <tn...@google.com> #2Aug 7, 2020 10:50PM

Reassigned to tn...@google.com.

Thanks for the report!

I found there is a typo in your configuration:

# keep names of exception classes
-keepname class * extends java.lang.Throwable

which should be "keepnames".

tn...@google.com <tn...@google.com> #3Aug 26, 2020 06:26PM

Marked as fixed.

We had a similar issue previously:

issue 113122600

.

But, I'm not able to repro the error. Without correcting the typo, I got:

$ java -jar build/libs/r8.jar --pg-conf ~/Downloads/proguard-rules.pro
Error in /usr/local/google/home/jsjeon/Downloads/proguard-rules.pro at line 2, column 6:
Expected [!]interface|@interface|class|enum
Compilation failed

which looks like the correct line/column numbers now.

pa...@gmail.com <pa...@gmail.com> #4Apr 28, 2021 09:48PM

Thanks!

I'm using at least two proguard files on input like
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'

I will try to reproduce it on some small test project.

tn...@google.com <tn...@google.com> #5May 3, 2021 07:38PM

One more note, after fix the typo, it crashed again on this

...\lib-about\build\intermediates\consumer_proguard_file\avastRelease\mergeAvastReleaseConsumerProguardFiles\proguard.txt:7:7: D8: Expected [!]interface|@interface|class|enum

This file looks like
1| -optimizations code/removal/simple,code/removal/advanced
2| -keepattributes SourceFile,LineNumberTable
3| -dontwarn **
4|
5| -keep class com.google.android.gms.common.GoogleApiAvailability { *; }
6| -keepname class com.actionbarsherlock.app.ActionBar
7| -keepname class com.viewpagerindicator.PagerIndicator
8| -keepname class com.nineoldandroids.view.ViewHelper
9| -keepname class com.jakewharton.disklrucache.DiskLruCache

It is the same issue.
But, again it should be line 6 instead of 7.
And also it should prefer path \lib-about\proguard-rules.pro instead of build/intermediates right?

Issue 161584622