How to get version of R8 that is being used by the Android Gradle Plugin?

How can I find out which version of R8 is being used by the Android Gradle Plugin for let's say 4.0.1?

buildscript {
  repositories {
    google()
    mavenCentral()
  }
  dependencies {
    classpath 'com.android.tools.build:gradle:4.0.1'
  }
}

Solution

This can be done by writing println(com.android.tools.r8.Version.getVersionString()) anywhere in your Gradle script and executing any Gradle Task or just calling the Gradle Wrapper.

buildscript {
  repositories {
    google()
    mavenCentral()
  }
  dependencies {
    classpath 'com.android.tools.build:gradle:4.0.1'
  }
}

println(com.android.tools.r8.Version.getVersionString())

Output:

$ ./gradlew

2.0.88 (build 19b089a1d5a73df8f00a27fda8b29b49782c621c from go/r8bot (luci-r8-ci-archive-0-z0tz))

This can also be added as a task to your Gradle script to not have it executed to configuration time:

tasks.register("r8Version") {
    doLast {
        println(com.android.tools.r8.Version.getVersionString())
    }
}

Running the :app:r8Version task:

$ ./gradlew :app:r8Version

> Task :app:r8Version
8.2.47 (build 62baf24ba2b71f4e5bc04c7f01930bc5d47b02be from go/r8bot (luci-r8-custom-ci-archive-0-19z6))