Java 9: cannot find symbol javax.annotation.Generated

/root/grpc-kotlin-hello/proto/src/main/java/io/grpc/examples/helloworld/GreeterGrpc.java:23: error: cannot find symbol
@javax.annotation.Generated(
^
symbol: class Generated
location: package javax.annotation
1 error

FAILURE: Build failed with an exception.

That class exists in Java 9: https://docs.oracle.com/javase/8/docs/api/javax/annotation/Generated.html . It seems like the problem is with an example that isn't maintained here.

Upgrade to Gradle 4.3

Okay... I've now run into this as well for our example after #3637.

For gRPC's build, after #3633 I don't see a problem with @Generated for :compileJava. But I do see it for :javadoc. But in the example @Generated is broken in :compileJava, even if depending on a grpc dep that built fine (e.g., grpc-testing-proto, but installed using Java 8). :-/

@onesea

@onesea, I'd suggest adding a dependency on javax.annotation:javax.annotation-api for the moment. It's possible to pass --add-modules java.xml.ws.annotation, but it seems it might cause more problems than it solves.

Upgrade to Gradle 4.3

I run into the same problem while working on Bazel build with Java 9: bazelbuild/bazel#4709.

The way it was fixed in other java based libraries, like auto-common, auto-value and dagger, is to dynamically select the right annotation to use:

Java 9: javax.annotation.processing.Generated
Java 8: javax.annotation.Generated

See e.g.: google/auto@f04406c, google/dagger#882.

@davido

@davido, dynamic selection doesn't really seem to be a solution except for annotation processors.

@ejona86

@ejona86 The other two options would be to detect the Java runtime or pass explicit option to gRpc compiler, a lá: --release 9 or similar?

I was able to patch gRpc compiler in Bazel tree, with this one liner:

diff --git a/third_party/grpc/compiler/src/java_plugin/cpp/java_generator.cpp b/third_party/grpc/compiler/src/java_plugin/cpp/java_generator.cpp
index 7cb01238ac..3264f15ecf 100644
--- a/third_party/grpc/compiler/src/java_plugin/cpp/java_generator.cpp
+++ b/third_party/grpc/compiler/src/java_plugin/cpp/java_generator.cpp
@@ -1203,7 +1203,7 @@ void GenerateService(const ServiceDescriptor* service,
   vars["NanoUtils"] = "io.grpc.protobuf.nano.NanoUtils";
   vars["StreamObserver"] = "io.grpc.stub.StreamObserver";
   vars["Iterator"] = "java.util.Iterator";
-  vars["Generated"] = "javax.annotation.Generated";
+  vars["Generated"] = "javax.annotation.processing.Generated";
   vars["ListenableFuture"] =
       "com.google.common.util.concurrent.ListenableFuture";
   vars["ExperimentalApi"] = "io.grpc.ExperimentalApi";

With this, the generated source is:

/**
 */
@javax.annotation.processing.Generated(
    value = "by gRPC proto compiler",
    comments = "Source: src/main/protobuf/command_server.proto")
public final class CommandServerGrpc {

  private CommandServerGrpc() {}
[...]

And the Bazel build on Java 9 just works:

  $ bazel --host_javabase=/usr/lib64/jvm/java-9-openjdk build --javacopt='--release 9' --java_toolchain=@bazel_tools//tools/jdk:toolchain_jdk9 src:bazel
[...]
INFO: From Compiling Java headers src/main/java/com/google/devtools/build/lib/worker/libworker-hjar.jar (16 files):
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.google.protobuf.UnsafeUtil (file:/home/davido/.cache/bazel/_bazel_davido/install/5906941a530f40a3f4749e5cfd148312/_embedded_binaries/embedded_tools/tools/jdk/turbine_deploy.jar) to field java.nio.Buffer.address
WARNING: Please consider reporting this to the maintainers of com.google.protobuf.UnsafeUtil
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
INFO: From Building src/main/java/com/google/devtools/build/lib/libbazel-main-class.jar (4 source files) and running annotation processors (OptionProcessor):
warning: Supported source version 'RELEASE_8' from annotation processor 'com.google.devtools.common.options.processor.OptionProcessor' less than -source '1.9'
Target //src:bazel up-to-date:
  bazel-bin/src/bazel
INFO: Elapsed time: 149.130s, Critical Path: 111.80s
INFO: Build completed successfully, 1986 total actions

Support building bazel with Java 9

@generated

Patch gRpc to use Java 9 @generated annotation

@generated

gRpc: Remove non supported @generated annotation for Java 9

Add javax.annotations to Bazel's third_party

@ejona86

@ejona86 As suggested, we added dependency to bazel on javax.annotation and added this as dependency to gRPC in Bazel tool chain, in: [1]. However, it was pointed out in the review, that this problem is going to be fixed upstream? Just wondering, as you said in comment to this issue, that you rather prefer that gRPC users will fix that problem?

If you are planning to address that problem upstream, do you have any time frame? I'm asking because this issue is very last issue, for full JDK 9 support in Bazel.

[1] https://bazel-review.googlesource.com/#/c/bazel/+/49490

@davido

I'd have no problem adding the dependency to java_grpc_library. It's been done for Blaze internally, for instance. I simply didn't think about it when I fixed up gradle+Java 9.

What's the easiest way to test out Bazel+Java 9? It should be as easy as adding a line to added_deps. @davido, if you have a working Bazel+Java 9 environment, I'd be happy to accept a PR.

The easiest way to reproduce the breakage on Bazel+Java 9, is to run this command in grpc-java:

  $ bazel --host_javabase=/usr/lib64/jvm/java-9-openjdk build --javacopt='--release 9' -- 
  java_toolchain=@bazel_tools//tools/jdk:toolchain_jdk9 examples:helloworld_java_grpc
 [...]
Target //examples:helloworld_java_grpc up-to-date:
  bazel-bin/examples/libhelloworld_java_grpc.jar
INFO: Elapsed time: 8.263s, Critical Path: 2.72s
INFO: 217 processes: 212 remote cache hit, 1 linux-sandbox, 3 local, 1 worker.
INFO: Build completed successfully, 243 total actions

I'm working on a fix and will upload a PR in a moment.

Bazel: Fix compilation in Java 9

Add javax.annotations to Bazel's third_party

Add a dependency on javax-annotations to java_grpc_library

Bazel: Fix compilation in Java 9

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Java 9: cannot find symbol javax.annotation.Generated #3633

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ejona86 commented on Oct 30, 2017

ejona86 commented on Oct 30, 2017

ejona86 commented on Oct 30, 2017

ejona86 commented on Oct 30, 2017

davido commented on Mar 8, 2018

davido commented on Mar 8, 2018

ejona86 commented on Mar 8, 2018

davido commented on Mar 8, 2018

davido commented on Mar 8, 2018

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davido commented on Apr 9, 2018

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