rules_jvm_external is failing with Bazel@HEAD

[sgowroji]

https://buildkite.com/bazel/bazel-at-head-plus-downstream/builds/3165#01895294-907c-4278-ba53-0049bc4ea142
Platform : Ubuntu, MacOs, Windows

Logs:

ERROR: /Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_jvm_external/tests/integration/kt_jvm_export/BUILD:3:14: in maven_project_jar rule //tests/integration/kt_jvm_export:test-project:
Traceback (most recent call last):
	File "/Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_jvm_external/private/rules/maven_project_jar.bzl", line 99, column 32, in _maven_project_jar_impl
		ijar = java_common.run_ijar(
	File "/virtual_builtins_bzl/common/java/java_common.bzl", line 86, column 68, in _run_ijar
Error in _check_java_toolchain_is_declared_on_rule: Rule 'maven_project_jar' in '/Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_jvm_external/tests/integration/kt_jvm_export/BUILD:3:14' must declare '@bazel_tools//tools/jdk:toolchain_type' toolchain in order to use java_common.
ERROR: /Users/buildkite/builds/bk-imacpro-6/bazel-downstream-projects/rules_jvm_external/tests/integration/kt_jvm_export/BUILD:3:14: Analysis of target '//tests/integration/kt_jvm_export:test-project' failed
ERROR: Analysis of target '//tests/integration/kt_jvm_export:test.publish' failed; build aborted: Analysis failed

Steps :

git clone https://github.com/bazelbuild/rules_jvm_external.git
git reset 39dcd72d72769acee2f02b869843259683f346c3 --hard
export USE_BAZEL_VERSION=53914865fc26850a1f282a83f3846c6103af217e
 shell_commands:
      - bazel run @unpinned_regression_testing//:pin
      - bazel run @unpinned_maven_install_in_custom_location//:pin
      - tests/bazel_run_tests.sh

Culprit bazelbuild/bazel@403564a

CC Greenteam @SalmaSamy

[fmeum]

Pretty sure the real culprit is bazelbuild/bazel@d0e2958. This is a breaking change for Bazel.

CC @kotlaja @hvadehra

[meteorcloudy]

I guess this should be fixed by some change like bazelbuild/rules_scala#1505?

[fmeum]

Fixing this forward looks reasonable to me and the same kind of change should fix this for rules_jvm_external.

This should be prominently listed as an incompatible change in Bazel 7 though.

[meteorcloudy]

@kotlaja I think we should try to follow https://bazel.build/release/backward-compatibility to guard this breaking change behind a flag (--incompatible_*).

[kotlaja]

I've added a github issue: bazelbuild/bazel#18970 and I would argue that we don't need an incompatible change because:

1. This is a temporary failure since it's just a preparation for the Automatic Exec Groups. Once AEGs are enabled, they will have similar error regarding this and AEGs already have their own incompatible flag. In other words, adding one more incompatible flag which will be soon deleted seems unnecessary.
2. The fix is super simple and it's rule-related, not target-related.

[kotlaja]

I've added a fix inside: #933, please have a look.

[fmeum]

Thanks for sending the fix!

2. The fix is super simple and it's rule-related, not target-related.

From the perspective of a Bazel user, rule-related breakages are typically more difficult to fix than target-related breakages since rulesets live in external repos and are third-party dependencies.

[fmeum]

Fixed by #933

[sgowroji]

Thanks @fmeum. We can close this issue.