The Android Gradle plugin (AGP) is scheduled to introduce a new feature in version 3.3.0 that makes Java compilation incremental when annotation processors are present.

I created this bug as a venue to provide the latest updates around this feature and to receive the community's feedback. (For more official announcements, please refer to our release notes: https://developer.android.com/studio/preview/features/.)

Starting with AGP 3.3.0-alpha10:
* For Kotlin-only or hybrid Kotlin-Java projects, Java compilation will always be incremental. (Before this release, Java compilation was not incremental if data binding or the retrolambda plugin was used; After this release, it is always incremental.)
* For Java-only projects:
- If annotation processors are not used or if all of the annotation processors are incremental, Java compilation will be incremental.
- If one or more annotation processors are non-incremental, Java compilation will not be incremental. We will warn users about non-incremental annotation processors and provide a flag for you to try out the new feature.
+ When the feature is enabled (android.enableSeparateAnnotationProcessing=true in the gradle.properties file):
~ The new ProcessAnnotationsTask performs annotation processing only, without compiling. As with Kapt in Kotlin projects, this task is not incremental (yet). Making this task and Kapt incremental will be a separate effort.
~ The existing JavaCompile task now performs compilation only, without annotation processing, and will be incremental.

Caveat:
- In projects using the Lombok annotation processor, JavaCompile will always perform annotation processing for Lombok, even when annotation processing was done earlier by Kapt or AGP's ProcessAnnotationsTask. (This fixes the issue where Lombok couldn't be used with Kotlin projects: https://youtrack.jetbrains.com/issue/KT-7112.)

The following are known issues in AGP 3.3.0-alpha10 that will be fixed in 3.3.0-alpha11:
1. The error message may read: "Consider setting the experimental feature flag BooleanOption.ENABLE_SEPARATE_ANNOTATION_PROCESSING=true in the gradle.properties file to run annotation processing in a separate task and make compilation incremental." The flag's name is incorrect. Please set android.enableSeparateAnnotationProcessing=true instead.
2. When the feature is first enabled or re-enabled after being disabled, the build may fail. Simply rebuild and it should succeed.
3. The feature does not work with projects using Lombok (this will be fixed in 3.3.0-alpha11).

Please let us know of any issues and performance gains as you try out this new feature. Thanks!

Issue 115774858

Mentioned issues (5)

Links (14)

Issue metadata