Ignore proguard configuration of an external library

Question

So, I want to add an external library to my project. The library itself is quite small, around 300 methods. But it is configured to be very liberal with it's proguard configuration. I ran a simple test with/without the library and with/without proguard on a barebones project and this is what I came up with

Proguard    Lib     Method Count
N           N       15631
Y           N       6370
N           Y       15945
Y           Y       15573

As you can see, with proguard enabled, the count is ~6000. But the moment I add the lib, count shoots up to ~15000 despite the library itself being only ~300 methods.

So my question is, how do I ignore the proguard configuration of this particular library?

UPDATE:

It is not possible with android gradle plugin now. I found android bug which doesn't have priority at all. Please avoid answers with mentioning "it is not possible" and keep question opened until a workaround or an official decision is possible. Otherwise, you will collect half of bounty without adding value. Thanks!

Answer 1

In this specific case you have a few options:

• extract the classes.jar file from the aar and include it as normal jar dependency in your project (will not work when the aar includes resources)
• change the aar and remove the consumer proguard rules from it
• use DexGuard which allows you to filter out unwanted consumer rules
• do a bit of gradle hacking, see below

Add the following to your build.gradle:

afterEvaluate {
  // All proguard tasks shall depend on our filter task
  def proguardTasks = tasks.findAll { task ->
    task.name.startsWith('transformClassesAndResourcesWithProguardFor') }
  proguardTasks.each { task -> task.dependsOn filterConsumerRules }
}

// Let's define our custom task that filters some unwanted
// consumer proguard rules
task(filterConsumerRules) << {
  // Collect all consumer rules first
  FileTree allConsumerRules = fileTree(dir: 'build/intermediates/exploded-aar',
                                       include: '**/proguard.txt')

  // Now filter the ones we want to exclude:
  // Change it to fit your needs, replace library with
  // the name of the aar you want to filter.
  FileTree excludeRules = allConsumerRules.matching {
    include '**/library/**'
  }

  // Print some info and delete the file, so ProGuard
  // does not pick it up. We could also just rename it.
  excludeRules.each { File file ->
    println 'Deleting ProGuard consumer rule ' + file
    file.delete()
  }
}

When using DexGuard (7.2.02+), you can add the following snippet to your build.gradle:

dexguard {
  // Replace library with the name of the aar you want to filter
  // The ** at the end will include every other rule.
  consumerRuleFilter '!**/library/**,**'
}

Mind that the logic is inverted to the ProGuard example above, the consumerRuleFilter will only include consumer rules that match the pattern.