Error: file '@com_google_protobuf//:protobuf.bzl' does not contain symbol 'py_proto_library'

[vorburger]

What version of protobuf and what language are you using?
Version: 30.2
Language: Java

What operating system (Linux, Windows, ...) and version?
Linux, Fedora 41

What did you do?
Trying to upgrade protobuf from 29.2 to 30.2 in a Bazel project, to benefit from #20867, see enola-dev/enola#1281.

What did you expect to see

Expected it to work.

What did you see instead?

./test.bash...
$ Bazel testing...
Loading: 0 packages loaded
ERROR: Traceback (most recent call last):
        File "/home/vorburger/.cache/bazel/_bazel_vorburger/a3cf8df34f0c7a76e9926daaad9ffbf4/external/protoc-gen-validate+/validate/BUILD", line 1, column 46, in <toplevel>
                load("@com_google_protobuf//:protobuf.bzl", "py_proto_library")
Error: file '@com_google_protobuf//:protobuf.bzl' does not contain symbol 'py_proto_library'
ERROR: /home/vorburger/.cache/bazel/_bazel_vorburger/a3cf8df34f0c7a76e9926daaad9ffbf4/external/protoc-gen-validate+/validate/BUILD: no such target '@@protoc-gen-validate+//validate:validate_proto': target 'validate_proto' not declared in package 'validate' defined by /home/vorburger/.cache/bazel/_bazel_vorburger/a3cf8df34f0c7a76e9926daaad9ffbf4/external/protoc-gen-validate+/validate/BUILD
ERROR: /home/vorburger/.cache/bazel/_bazel_vorburger/a3cf8df34f0c7a76e9926daaad9ffbf4/external/xds+/xds/service/orca/v3/BUILD:5:18: no such target '@@protoc-gen-validate+//validate:validate_proto': target 'validate_proto' not declared in package 'validate' defined by /home/vorburger/.cache/bazel/_bazel_vorburger/a3cf8df34f0c7a76e9926daaad9ffbf4/external/protoc-gen-validate+/validate/BUILD and referenced by '@@xds+//xds/service/orca/v3:pkg'
ERROR: Analysis of target '//java/dev/enola:enola.publish' failed; build aborted: Analysis failed
INFO: Elapsed time: 0.330s
INFO: 0 processes.
ERROR: Build did NOT complete successfully
ERROR: Couldn't start the build. Unable to run tests

Looks like #10132 (comment), but that is ancient.

[zhangskz]

This is WAI per the following breaking change announced in Python: https://protobuf.dev/news/v30/#remove-deprecated-py_proto_library-macro

This py_proto_library implemenetation is deprecate / internally only and should be replaced with the official py_proto_library implementation

[vorburger]

@zhangskz but... it's broken. I have a working project, and am just bumping protobuf from version 29.2 to 30.2, and hitting this. I think what you are really saying telling me is that is due to something else than my project still using that py_proto_library...

... given external/protoc-gen-validate+/validate/BUILD, I gathered that this seem to have something to do with https://registry.bazel.build/modules/protoc-gen-validate. Indeed, adding bazel_dep(name = "protoc-gen-validate", version = "1.2.1.bcr.1") does the trick and fixes this.

However I'm then hitting #21302, but that's an unrelated problem.

[zhangskz]

Yep, updating protoc-gen-validate+ (and any other deps w incompatibilities) to a version compatible with v30.0 (incl. this python breaking change) should be sufficient.

Note that 30.x was a major version bump in several languages (see https://protobuf.dev/support/version-support/), so in python this is actually 5.29.x->6.30.x.