no matching toolchains found for types @io_bazel_rules_scala//scala_proto:toolchain_type

[luser]

I'm having an issue using scalapb_proto_library. I've built a simple reduced testcase project here: https://github.com/luser/bazel-scala-proto-test

I'm using bazel 0.26.1:

└─ $ ▶ bazel version
Build label: 0.26.1
Build target: bazel-out/darwin-opt/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
Build time: Thu Jun 6 11:08:11 2019 (1559819291)
Build timestamp: 1559819291

The error is:

└─ $ ▶ bazel build :scala-proto-test
DEBUG: Rule 'io_bazel_rules_scala' indicated that a canonical reproducible form can be obtained by modifying arguments sha256 = "8fe6f562da6469d5e67032ce3a9aa19a4cd312e8b284060e531c369067b3ceaa"
ERROR: Analysis of target '//:scala-proto-test' failed; build aborted: no matching toolchains found for types @io_bazel_rules_scala//scala_proto:toolchain_type
INFO: Elapsed time: 0.121s
INFO: 0 processes.
FAILED: Build did NOT complete successfully (0 packages loaded, 0 targets configured)

I am very new to Bazel and I'm also not incredibly up-to-speed on Scala so it's possible I'm just doing something wrong, but I'd appreciate any help!

[johnynek]

You need to set up a toolchain. There is some documentation here:

https://github.com/bazelbuild/rules_scala/blob/master/docs/scalapb_proto_library.md#scalapb_proto_library

[luser]

I did attempt to do that but it doesn't seem to be working:
https://github.com/luser/bazel-scala-proto-test/blob/f1aefee9cdfc806a3638b80193be1a4075e82a87/BUILD#L5-L18

[luser]

So I tried reworking things with the other rules_scala and hit the same problem. After some fumbling around and reading the Bazel docs on toolchains I realized that toolchains need to be registered in WORKSPACE, and the other rules_scala provides a scala_proto_register_toolchains() to do so, which made things work. It looks like this project provides the same method, it's just not mentioned in the docs anywhere.

[luser]

The solution that worked for me was to add this to WORKSPACE:

load("@io_bazel_rules_scala//scala_proto:toolchains.bzl", "scala_proto_register_toolchains")
scala_proto_register_toolchains()

It'd be great if the docs mentioned this!

[ittaiz]

Any chance you can send a PR to the docs?

…

On Fri, Jun 14, 2019 at 3:11 AM Ted Mielczarek ***@***.***> wrote: The solution that worked for me was to add this to WORKSPACE: ***@***.***_bazel_rules_scala//scala_proto:toolchains.bzl", "scala_proto_register_toolchains") scala_proto_register_toolchains() It'd be great if the docs mentioned this! — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#768?email_source=notifications&email_token=AAKQQF52HAYU7YEHV7UKHOLP2LO3LA5CNFSM4HXNXGAKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGODXVLT3Q#issuecomment-501922286>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAKQQF2DDH43UBDSGHALY4TP2LO3LANCNFSM4HXNXGAA> .