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Stick with protoc-{bridge,gen}_2.13 under Scala 3
As noted in the comment added to `select_root_artifacts()`,
`com.thesamet.scalapb:compilerplugin_3:0.11.17` depends on
`com.thesamet.scalapb:protoc-gen_2.13:0.9.7`. When using
`com.thesamet.scalapb:protoc-gen_3:0.9.8` instead, we get a crash:
```txt
$ bazel build --repo_env=SCALA_VERSION=3.6.2 //third_party/test/proto:scala
[ ...snip... ]
ERROR: third_party/test/proto/BUILD.bazel:4:14:
ProtoScalaPBRule
third_party/test/proto/proto_jvm_extra_protobuf_generator_scalapb.srcjar
failed: (Exit 1): scalapb_worker failed:
error executing command (from target //third_party/test/proto:proto)
bazel-out/darwin_arm64-opt-exec-2B5CBBC6/bin/src/scala/scripts/scalapb_worker
...
--scala_out: java.lang.NoClassDefFoundError:
Could not initialize class scalapb.ScalaPbCodeGenerator$
at scripts.ScalaPbCodeGenerator$.process(ScalaPbCodeGeneratorWrapper.scala:7)
at protocgen.CodeGenApp.run(CodeGenApp.scala:48)
at protocgen.CodeGenApp.run$(CodeGenApp.scala:23)
at scripts.ScalaPbCodeGenerator$.run(ScalaPbCodeGeneratorWrapper.scala:5)
at protocgen.CodeGenApp.run(CodeGenApp.scala:33)
at protocgen.CodeGenApp.run$(CodeGenApp.scala:23)
at scripts.ScalaPbCodeGenerator$.run(ScalaPbCodeGeneratorWrapper.scala:5)
at protocbridge.frontend.PluginFrontend$.runWithBytes(PluginFrontend.scala:48)
at protocbridge.frontend.PluginFrontend$.runWithInputStream(PluginFrontend.scala:113)
at protocbridge.frontend.SocketBasedPluginFrontend.prepare$$anonfun$1$$anonfun$1(SocketBasedPluginFrontend.scala:31)
at protocbridge.frontend.SocketBasedPluginFrontend.prepare$$anonfun$1$$anonfun$adapted$1(SocketBasedPluginFrontend.scala:37)
at scala.concurrent.impl.ExecutionContextImpl$DefaultThreadFactory$$anon$1$$anon$2.block(ExecutionContextImpl.scala:60)
at java.base/java.util.concurrent.ForkJoinPool.managedBlock(ForkJoinPool.java:3118)
at scala.concurrent.impl.ExecutionContextImpl$DefaultThreadFactory$$anon$1.blockOn(ExecutionContextImpl.scala:71)
at scala.concurrent.package$.blocking(package.scala:124)
at protocbridge.frontend.SocketBasedPluginFrontend.prepare$$anonfun$1(SocketBasedPluginFrontend.scala:37)
at protocbridge.frontend.SocketBasedPluginFrontend.prepare$$anonfun$adapted$1(SocketBasedPluginFrontend.scala:38)
at scala.concurrent.Future$.$anonfun$apply$1(Future.scala:687)
at scala.concurrent.impl.Promise$Transformation.run(Promise.scala:467)
at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1426)
at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)
java.lang.RuntimeException: Exit with code 1
at scala.sys.package$.error(package.scala:27)
at scripts.ScalaPBWorker$.work(ScalaPBWorker.scala:44)
at io.bazel.rulesscala.worker.Worker.persistentWorkerMain(Worker.java:96)
at io.bazel.rulesscala.worker.Worker.workerMain(Worker.java:49)
at scripts.ScalaPBWorker$.main(ScalaPBWorker.scala:39)
at scripts.ScalaPBWorker.main(ScalaPBWorker.scala)
Target //third_party/test/proto:scala failed to build
ERROR: test/proto/BUILD.bazel:4:14
scala @//third_party/test/proto:proto failed:
(Exit 1): scalapb_worker failed:
error executing command (from target //third_party/test/proto:proto)
```
---
As I was going back and testing some more, I couldn't reproduce the
`ProtoScalaPBRule` hanging by setting `protoc-bridge` to 0.9.7 and
`protobuf` to v26.1. I was using this command (using Bazel 7.4.1 to
avoid setting C++ compiler flags for Bazel 6.5.0):
```txt
USE_BAZEL_VERSION=7.4.1 bazel build //third_party/test/proto:scala
```
The command kept crashing every time, instead of hanging. I eventually
realized this was because of two things:
- `scalarules.test.extra_protobuf_generator.ExtraProtobufGenerator.run`
was still catching `Throwable`, since Scala 2.11 support ends with
`protoc-bridge` 0.7.14.
- Bazel kept persistent `io.bazel.rulesscala.scalac.ScalacWorker`
workers running with `ExtraProtobufGenerator` code that still had the
`try`/`catch` block after I tried removing it.
After temporarily editing out the `try`/`catch` block from
`ExtraProtobufGenerator.run` and running `bazel shutdown`, I could
reproduce the hang. I could then confirm `protoc-bridge` 0.9.8 fixed it.
---
Also, TIL that `scripts.ScalaPbCodeGenerator.process` (from
`src/scala/scripts/ScalaPbCodeGeneratorWrapper`) never needed a
`try`/`catch` block. When bumping to
`com.thesamet.scalapb:compilerplugin_2.12:0.11.17` in bazelbuild#1648
(commit 23ae356),
`scalapb.ScalaPbCodeGenerator` went from implementing
`protocbridge.ProtocCodeGenerator` to implementing
`protocgen.CodeGenApp`:
- https://github.com/scalapb/ScalaPB/blob/v0.9.7/compiler-plugin/src/main/scala/scalapb/ScalaPbCodeGenerator.scala#L9
- https://github.com/scalapb/ScalaPB/blob/v0.11.17/compiler-plugin/src/main/scala/scalapb/ScalaPbCodeGenerator.scala#L11
That commit introduced `com.thesamet.scalapb:protoc-gen_2.12:0.9.7`, and
`protocgen.CodeGenApp.run()` already had a `try`/`catch` block for
`Throwable`:
- https://github.com/scalapb/protoc-bridge/blob/v0.9.7/protoc-gen/src/main/scala/protocgen/CodeGenApp.scala#L49-L56
However, `protocbridge.ProtocCodeGenerator`, which
`protocgen.CodeGenApp` extends, only declares a `run()` method with no
implementation (and no `try`/`catch` block):
- https://github.com/scalapb/protoc-bridge/blob/v0.9.7/bridge/src/main/scala/protocbridge/ProtocCodeGenerator.scala#L5
The aforementioned `ExtraProtobufGenerator` only extends
`protocbridge.ProtocCodeGenerator`, not `protocgen.CodeGenApp`. That's
why it will still hang when we remove the `try`/`catch` block from its
`run()` method and run with `protoc-bridge` 0.9.7 and `protobuf` >
v25.5.- Loading branch information
