Hey folks, I'm having trouble building mainline Pants:

error: failed to run custom build command for `protos v0.0.1 ($pantsdir/src/rust/engine/protos)`

Caused by:
  process didn't exit successfully: `$pantsdir/src/rust/engine/target/debug/build/protos-e2c47360b0048589/build-script-build` (exit status: 1)
  --- stdout
  cargo:rerun-if-changed=protos/bazelbuild_remote-apis/build/bazel/remote/execution/v2/remote_execution.proto
  cargo:rerun-if-changed=protos/bazelbuild_remote-apis/build/bazel/semver/semver.proto
  cargo:rerun-if-changed=protos/buildbarn/cas.proto
  cargo:rerun-if-changed=protos/googleapis/google/bytestream/bytestream.proto
  cargo:rerun-if-changed=protos/googleapis/google/rpc/code.proto
  cargo:rerun-if-changed=protos/googleapis/google/rpc/error_details.proto
  cargo:rerun-if-changed=protos/googleapis/google/rpc/status.proto
  cargo:rerun-if-changed=protos/googleapis/google/longrunning/operations.proto
  cargo:rerun-if-changed=protos/pants/cache.proto
  cargo:rerun-if-changed=protos/standard/google/protobuf/empty.proto
  cargo:rerun-if-changed=protos/bazelbuild_remote-apis
  cargo:rerun-if-changed=protos/buildbarn
  cargo:rerun-if-changed=protos/googleapis
  cargo:rerun-if-changed=protos/pants
  cargo:rerun-if-changed=protos/standard

  --- stderr
  Error: Custom { kind: Other, error: "protoc failed: google/bytestream/bytestream.proto:20:1: warning: Import google/protobuf/wrappers.proto is unused.\ngoogle/bytestream/bytestream.proto:19:1: warning: Import google/api/annotations.proto is unused.\ncache.proto: This file contains proto3 optional fields, but --experimental_allow_proto3_optional was not set.\n" }
warning: build failed, waiting for other jobs to finish...

protoc version is "libprotoc 3.12.4", OS is Ubuntu 22.04.4 LTS . Anyone have any pointers?

Silly question, is this the same problem if you build in release mode?

we use protoc v23.x on CI

it's default on ubuntu 22, maybe it's time to upgrade lol. It does build fine in release mode!

@careful-address-89803 DId that work for you?

Thank you! I too was using the ubuntu default 3.12.4. I updated to 23.4 (installed in ~/.local) and now I can build pants again 🙂.

yep, works now. Thanks!