"error: [ExtendsAutoValue] Do not extend an @AutoValue/@AutoOneOf class in non-generated code" flagged by error prone

[davido]

I bumped error prone to 2.3.4 in Bazel, and conducted custom java tools release to catch more warnings in Gerrit Code Review project.

With bumped error prone version I see this breakage in Gerrit build, in rules_closure:

  $ bazel build --java_toolchain=@remote_java_tools_linux//:toolchain --host_java_toolchain=@remote_java_tools_linux//:toolchain :release
  [...]
INFO: Analyzed target //:release (129 packages loaded, 787 targets configured).
INFO: Found 1 target...
ERROR: /home/davido/.cache/bazel/_bazel_davido/5c01f4f713b675540b8b424c5c647f63/external/io_bazel_rules_closure/java/io/bazel/rules/closure/BUILD:40:13: Building external/io_bazel_rules_closure/java/io/bazel/rules/closure/libtarjan.jar (1 source file) and running annotation processors (AutoAnnotationProcessor, AutoOneOfProcessor, AutoValueProcessor) failed (Exit 1)
bazel-out/host/bin/external/io_bazel_rules_closure/java/io/bazel/rules/closure/_javac/tarjan/libtarjan_sourcegenfiles/io/bazel/rules/closure/AutoValue_Tarjan_Result.java:8: error: [ExtendsAutoValue] Do not extend an @AutoValue/@AutoOneOf class in non-generated code.
 final class AutoValue_Tarjan_Result<V> extends Tarjan.Result<V> {
       ^
    (see https://errorprone.info/bugpattern/ExtendsAutoValue)
Target //:release failed to build
Use --verbose_failures to see the command lines of failed build steps.
INFO: Elapsed time: 44.028s, Critical Path: 26.56s
INFO: 69 processes: 4 remote cache hit, 47 linux-sandbox, 2 local, 16 worker.
FAILED: Build did NOT complete successfully

Workaround for now would be to disable that check or downgrade the severity to warning.

[davido]

Reproducer.

Apply this diff:

diff --git a/WORKSPACE b/WORKSPACE
index c6cad80..f1c1f87 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -7,6 +7,23 @@ load("@io_bazel_rules_closure//closure:repositories.bzl", "rules_closure_depende
 rules_closure_dependencies()
 rules_closure_toolchains()
 
+http_archive(
+    name = "remote_java_tools_linux",
+    sha256 = "74d30ccf161c58bb69db9b2171c954a0563b2d1ff6f5831debbe71ced105c388",
+    urls = [
+        "https://github.com/davido/java_tools/releases/download/javac11-v11.0/java_tools_javac11_linux-v11.0.zip",
+    ],
+)
+
+http_archive(
+    name = "remote_java_tools_darwin",
+    sha256 = "252520f0cd5dd7e9b18062dc731f8ae248993650f12a9b613fcd9ebda591d242",
+    urls = [
+        "https://github.com/davido/java_tools/releases/download/javac11-v11.0/java_tools_javac11_darwin-v11.0.zip",
+ ],
+)
+
+
 http_archive(
     name = "bazel_skylib",
     sha256 = "bbccf674aa441c266df9894182d80de104cabd19be98be002f6d478aaa31574d",

And run:

  $ bazel build --java_toolchain=@remote_java_tools_linux//:toolchain --host_java_toolchain=@remote_java_tools_linux//:toolchain //...
INFO: Analyzed 1357 targets (136 packages loaded, 1603 targets configured).
INFO: Found 1357 targets...
ERROR: /home/davido/projects/davido_rules_clsoure/java/io/bazel/rules/closure/BUILD:40:13: Building java/io/bazel/rules/closure/libtarjan.jar (1 source file) and running annotation processors (AutoAnnotationProcessor, AutoOneOfProcessor, AutoValueProcessor) failed (Exit 1)
bazel-out/host/bin/java/io/bazel/rules/closure/_javac/tarjan/libtarjan_sourcegenfiles/io/bazel/rules/closure/AutoValue_Tarjan_Result.java:8: error: [ExtendsAutoValue] Do not extend an @AutoValue/@AutoOneOf class in non-generated code.
 final class AutoValue_Tarjan_Result<V> extends Tarjan.Result<V> {
       ^
    (see https://errorprone.info/bugpattern/ExtendsAutoValue)
INFO: Elapsed time: 71.663s, Critical Path: 4.61s
INFO: 11 processes: 7 linux-sandbox, 4 worker.
FAILED: Build did NOT complete successfully

[gkdn]

Went over this. I don't see rules_closure doing anything special around auto value.

Looking at error-prone: the class is suppose to be skipped by javax.annotation.Generated, javax.annotation.processing.Generated annotation. And AutoValue would add that annotation if it exists.

So things you can try:

1. Check if AutoValue is adding Generated. If it s adding that, you should seek help on error prone side.
2. If it is not adding it: try upgrading AutoValue just in case to if there was any improvements around that and also check if your custom toolchain has the annotation.

But anyway I don't think there is much to do on the rules_closure if upgrading AutoValue doesn't help.

[davido]

@gkdn Thanks for looking into it.

I think the issue is similar to rules_kotlin, see my PR here: [1], and the issue here: [2]. auto-value cannot add @generated annotation, because it is not on the classpath: javax.annotation dependency is missing. And javax.annotation.processing.Generated cannot be used, because source language level is Java 8 (that's the default in Bazel).

If you check the generated files in rules_closure, there is no annotation emitted by auto-value, only this comment:

vim bazel-out/host/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_sourcegenfiles/io/bazel/rules/closure/webfiles/AutoValue_Webfile.java

package io.bazel.rules.closure.webfiles;

import io.bazel.rules.closure.Webpath;
import java.nio.file.Path;

// Generated by com.google.auto.value.processor.AutoValueProcessor
 final class AutoValue_Webfile extends Webfile {

We wouldn't care much that the @generated annotation is missing on generated files, but the new Error Prone version 2.3.4, that I'm trying to upgrade in Bazel (in this PR: [3]) is flagging the code as invalid.

I will upload PR for review in a moment.

[1] bazelbuild/rules_kotlin#320
[2] bazelbuild/rules_kotlin#321
[3] bazelbuild/bazel#11271

[davido]

With the referenced PR, the @generated annotation is now there and this makes new version of Error Prone totally happy, no failure any more:

vim bazel-out/host/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_sourcegenfiles/io/bazel/rules/closure/webfiles/AutoValue_Webfile.java

package io.bazel.rules.closure.webfiles;

import io.bazel.rules.closure.Webpath;
import java.nio.file.Path;
import javax.annotation.Generated;

@Generated("com.google.auto.value.processor.AutoValueProcessor")
 final class AutoValue_Webfile extends Webfile {

  private final Webpath webpath;
  private final Path zip;
  private final String label;
  private final BuildInfo.WebfileInfo info;

[davido]

The reason why @generated annotation is missing is the same as pointed out by @cushon in google/error-prone#1348 (comment).

rules_closure is building also for host configuration. So the situation before applying the PR linked to this issue is already broken, and Error Prone upgrade only detects and reports it:

  $ java -fullversion
openjdk full version "1.8.0_242-b08"

  $ bazel build //...
  $ cd bazel-out

  $ find . -name "Auto*"
  ./k8-fastbuild/bin/javatests/io/bazel/rules/closure/worker/testing/_javac/testing/libtesting_sourcegenfiles/io/bazel/rules/closure/worker/testing/AutoValue_ProgramResult.java
./k8-fastbuild/bin/javatests/io/bazel/rules/closure/worker/testing/_javac/testing/libtesting_classes/io/bazel/rules/closure/worker/testing/AutoValue_ProgramResult.class
./k8-fastbuild/bin/java/io/bazel/rules/closure/_javac/tarjan/libtarjan_sourcegenfiles/io/bazel/rules/closure/AutoValue_Tarjan_Result.java
./k8-fastbuild/bin/java/io/bazel/rules/closure/_javac/tarjan/libtarjan_classes/io/bazel/rules/closure/AutoValue_Tarjan_Result.class
./k8-fastbuild/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_classes/io/bazel/rules/closure/webfiles/AutoValue_Webset.class
./k8-fastbuild/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_classes/io/bazel/rules/closure/webfiles/AutoValue_Webfile.class
./k8-fastbuild/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_sourcegenfiles/io/bazel/rules/closure/webfiles/AutoValue_Webfile.java
./k8-fastbuild/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_sourcegenfiles/io/bazel/rules/closure/webfiles/AutoValue_Webset.java
./k8-fastbuild/bin/java/io/bazel/rules/closure/worker/_javac/worker/libworker_classes/io/bazel/rules/closure/worker/AutoValue_InputCache_Key.class
./k8-fastbuild/bin/java/io/bazel/rules/closure/worker/_javac/worker/libworker_sourcegenfiles/io/bazel/rules/closure/worker/AutoValue_InputCache_Key.java
./host/bin/java/io/bazel/rules/closure/_javac/tarjan/libtarjan_sourcegenfiles/io/bazel/rules/closure/AutoValue_Tarjan_Result.java
./host/bin/java/io/bazel/rules/closure/_javac/tarjan/libtarjan_classes/io/bazel/rules/closure/AutoValue_Tarjan_Result.class
./host/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_sourcegenfiles/io/bazel/rules/closure/webfiles/AutoValue_Webfile.java
./host/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_sourcegenfiles/io/bazel/rules/closure/webfiles/AutoValue_Webset.java
./host/bin/java/io/bazel/rules/closure/worker/_javac/worker/libworker_classes/io/bazel/rules/closure/worker/AutoValue_InputCache_Key.class
./host/bin/java/io/bazel/rules/closure/worker/_javac/worker/libworker_sourcegenfiles/io/bazel/rules/closure/worker/AutoValue_InputCache_Key.java

Now, as expected, in ./k8-fastbuild/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_sourcegenfiles/io/bazel/rules/closure/webfiles/AutoValue Webfile.java, the annotation is there:

package io.bazel.rules.closure.webfiles;

import io.bazel.rules.closure.Webpath;
import java.nio.file.Path;
import javax.annotation.Generated;

@Generated("com.google.auto.value.processor.AutoValueProcessor")
final class AutoValue_Webfile extends Webfile {
[...]

But in: ./host/bin/java/io/bazel/rules/closure/webfiles/_javac/webfiles/libwebfiles_sourcegenfiles/io/bazel/rules/closure/webfiles/AutoValue_Webfile.java, it is missing:

package io.bazel.rules.closure.webfiles;

import io.bazel.rules.closure.Webpath;
import java.nio.file.Path;

// Generated by com.google.auto.value.processor.AutoValueProcessor
final class AutoValue_Webfile extends Webfile {
[...]

The missing annotation generation is using -source 8 -target 8 with a JDK 11 -bootclasspath (because it's targeting the remote JDK 11). So AutoValue processor is trying to use javax.annotation.Generated based on the source level, but it isn't available because the JDK 11 bootclasspath only contains javax.annotation.processing.Generated.

[davido]

As of: [1] Gerrit removed rules_closure dependency.

[1] https://gerrit-review.googlesource.com/c/gerrit/+/272773