Action conflicts: 'foo.repo_mapping' is generated by these conflicting actions

[dzbarsky]

Description of the bug:

This seems like an 8.5 regression under coverage.

Full error:

(20:26:23) ERROR: file 'test/unit/debug_info/test-2282882243/myrusttest.repo_mapping' is generated by these conflicting actions:
Label: //test/unit/debug_info:myrusttest
RuleClass: rust_test rule
JavaActionClass: class com.google.devtools.build.lib.analysis.RepoMappingManifestAction
Configuration: fc009888277660f88b19e6ceb6bb06fc13b096a64c55515624720a7efa31dbfd, c3f664967775ba0a33b3c89f4c7fce8c56b05aad1d56c43a445c63f27133c655
Mnemonic: RepoMappingManifest
Action key: 930ed508831bb3eb42749ca75e5695206fab55c4ac80fa80b2a1db16aad69c33, a793df2bd4717c6fb3af51c213cfcc306a60f42266e57dbd65d601c2abb30b95
Progress message: Writing repo mapping manifest for //test/unit/debug_info:myrusttest
Action describeKey: (null)
PrimaryInput: (null)
PrimaryOutput: File:[[<execution_root>]bazel-out/darwin_arm64-fastbuild/bin]test/unit/debug_info/test-2282882243/myrusttest.repo_mapping
Owner information: ConfiguredTargetKey{label=//test/unit/debug_info:myrusttest, config=BuildConfigurationKey[fc009888277660f88b19e6ceb6bb06fc13b096a64c55515624720a7efa31dbfd]}, ConfiguredTargetKey{label=//test/unit/debug_info:myrusttest, config=BuildConfigurationKey[c3f664967775ba0a33b3c89f4c7fce8c56b05aad1d56c43a445c63f27133c655]}
MandatoryInputs: are equal
Outputs: are equal
(20:26:23) ERROR: file 'test/unit/debug_info/test-2282882243/myrusttest.repo_mapping' is generated by these conflicting actions:
Label: //test/unit/debug_info:myrusttest
RuleClass: rust_test rule
JavaActionClass: class com.google.devtools.build.lib.analysis.RepoMappingManifestAction
Configuration: fc009888277660f88b19e6ceb6bb06fc13b096a64c55515624720a7efa31dbfd, c3f664967775ba0a33b3c89f4c7fce8c56b05aad1d56c43a445c63f27133c655
Mnemonic: RepoMappingManifest
Action key: 930ed508831bb3eb42749ca75e5695206fab55c4ac80fa80b2a1db16aad69c33, a793df2bd4717c6fb3af51c213cfcc306a60f42266e57dbd65d601c2abb30b95
Progress message: Writing repo mapping manifest for //test/unit/debug_info:myrusttest
Action describeKey: (null)
PrimaryInput: (null)
PrimaryOutput: File:[[<execution_root>]bazel-out/darwin_arm64-fastbuild/bin]test/unit/debug_info/test-2282882243/myrusttest.repo_mapping
Owner information: ConfiguredTargetKey{label=//test/unit/debug_info:myrusttest, config=BuildConfigurationKey[fc009888277660f88b19e6ceb6bb06fc13b096a64c55515624720a7efa31dbfd]}, ConfiguredTargetKey{label=//test/unit/debug_info:myrusttest, config=BuildConfigurationKey[c3f664967775ba0a33b3c89f4c7fce8c56b05aad1d56c43a445c63f27133c655]}
MandatoryInputs: are equal
Outputs: are equal

Which category does this issue belong to?

No response

What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Non-minimal repro:

bazelbuild/rules_rust#3785
https://buildkite.com/bazel/rules-rust-rustlang/builds/16186#019b32ec-60de-4972-a57d-d47177161cf1

Which operating system are you running Bazel on?

No response

What is the output of bazel info release?

No response

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

No response

What's the output of git remote get-url origin; git rev-parse HEAD ?

If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

No response

Have you found anything relevant by searching the web?

No response

Any other information, logs, or outputs that you want to share?

No response

[Wyverald]

Could you diff the two configs (using bazel config) and see what's different?

[fmeum]

This could be due to the test trimming transition affecting the set of loaded packages through config fields (e.g. lcov_merger). Just a guess at this point though.

[dzbarsky]

➜  rules_rust git:(zbarsky/linkz) ✗ diff -U8 /tmp/config1 /tmp/config2
--- /tmp/config1	2025-12-19 07:00:14
+++ /tmp/config2	2025-12-19 07:00:21
@@ -1,10 +1,10 @@
-BuildConfigurationValue 724da8a8f463ad1345600602fe1f968297cfd31b48f2fa1c261104c0bd3ffad4:
-Skyframe Key: BuildConfigurationKey[724da8a8f463ad1345600602fe1f968297cfd31b48f2fa1c261104c0bd3ffad4]
+BuildConfigurationValue 17057e0964cdddc6443ec484c1a7c13f31b80fbfeb909a58071ae223bddbd5ef:
+Skyframe Key: BuildConfigurationKey[17057e0964cdddc6443ec484c1a7c13f31b80fbfeb909a58071ae223bddbd5ef]
 Fragments: com.google.devtools.build.lib.analysis.PlatformConfiguration: [com.google.devtools.build.lib.analysis.PlatformOptions], com.google.devtools.build.lib.analysis.ShellConfiguration: [com.google.devtools.build.lib.analysis.ShellConfiguration$Options], com.google.devtools.build.lib.analysis.test.CoverageConfiguration: [com.google.devtools.build.lib.analysis.config.CoreOptions,com.google.devtools.build.lib.analysis.test.CoverageConfiguration$CoverageOptions], com.google.devtools.build.lib.analysis.test.TestConfiguration: [com.google.devtools.build.lib.analysis.test.TestConfiguration$TestOptions], com.google.devtools.build.lib.bazel.BazelConfiguration: [com.google.devtools.build.lib.bazel.BazelConfiguration$Options], com.google.devtools.build.lib.bazel.rules.BazelRuleClassProvider$StrictActionEnvConfiguration: [com.google.devtools.build.lib.bazel.rules.BazelRuleClassProvider$StrictActionEnvOptions], com.google.devtools.build.lib.bazel.rules.python.BazelPythonConfiguration: [com.google.devtools.build.lib.bazel.rules.python.BazelPythonConfiguration$Options,com.google.devtools.build.lib.rules.python.PythonOptions], com.google.devtools.build.lib.rules.android.AndroidConfiguration: [com.google.devtools.build.lib.rules.android.AndroidConfiguration$Options], com.google.devtools.build.lib.rules.android.BazelAndroidConfiguration: [com.google.devtools.build.lib.rules.android.BazelAndroidConfiguration$Options], com.google.devtools.build.lib.rules.apple.AppleConfiguration: [com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions], com.google.devtools.build.lib.rules.config.ConfigFeatureFlagConfiguration: [com.google.devtools.build.lib.rules.config.ConfigFeatureFlagOptions], com.google.devtools.build.lib.rules.cpp.CppConfiguration: [com.google.devtools.build.lib.rules.cpp.CppOptions], com.google.devtools.build.lib.rules.genquery.GenQueryConfiguration: [com.google.devtools.build.lib.rules.genquery.GenQueryConfiguration$GenQueryOptions], com.google.devtools.build.lib.rules.java.JavaConfiguration: [com.google.devtools.build.lib.analysis.PlatformOptions,com.google.devtools.build.lib.rules.java.JavaOptions], com.google.devtools.build.lib.rules.objc.J2ObjcConfiguration: [com.google.devtools.build.lib.rules.objc.J2ObjcCommandLineOptions], com.google.devtools.build.lib.rules.objc.ObjcConfiguration: [com.google.devtools.build.lib.rules.objc.ObjcCommandLineOptions], com.google.devtools.build.lib.rules.proto.ProtoConfiguration: [com.google.devtools.build.lib.rules.proto.ProtoConfiguration$Options], com.google.devtools.build.lib.rules.python.PythonConfiguration: [com.google.devtools.build.lib.rules.python.PythonOptions], 
 FragmentOptions com.google.devtools.build.lib.analysis.PlatformOptions {
   experimental_add_exec_constraints_to_targets: []
   extra_execution_platforms: []
   extra_toolchains: []
   host_platform: @@bazel_tools//tools:host_platform
   incompatible_use_toolchain_resolution_for_java_rules: true
   platform_mappings: PlatformMappingKey{path=platform_mappings, wasExplicitlySetByUser=false}
@@ -80,16 +80,39 @@
   strict_filesets: false
   target_environment: []
   test_env: []
 }
 FragmentOptions com.google.devtools.build.lib.analysis.test.CoverageConfiguration$CoverageOptions {
   coverage_output_generator: @@bazel_tools//tools/test:lcov_merger
   coverage_report_generator: @@bazel_tools//tools/test:coverage_report_generator
 }
+FragmentOptions com.google.devtools.build.lib.analysis.test.TestConfiguration$TestOptions {
+  allow_local_tests: true
+  cache_test_results: AUTO
+  coverage_support: @@bazel_tools//tools/test:coverage_support
+  default_test_resources: []
+  experimental_cancel_concurrent_tests: NEVER
+  experimental_fetch_all_coverage_outputs: true
+  experimental_retain_test_configuration_across_testonly: false
+  experimental_split_coverage_postprocessing: false
+  incompatible_check_sharding_support: true
+  incompatible_exclusive_test_sandboxed: true
+  runs_per_test: [(?:(?>.*)) Options: [1]]
+  runs_per_test_detects_flakes: false
+  test_arg: []
+  test_filter: null
+  test_result_expiration: -1
+  test_runner_fail_fast: false
+  test_sharding_strategy: EXPLICIT
+  test_timeout: {short=PT5M, moderate=PT10M, long=PT20M, eternal=PT1H}
+  trim_test_configuration: true
+  use_target_platform_for_tests: false
+  zip_undeclared_test_outputs: false
+}
 FragmentOptions com.google.devtools.build.lib.bazel.BazelConfiguration$Options {
   incompatible_check_visibility_for_toolchains: false
 }
 FragmentOptions com.google.devtools.build.lib.bazel.rules.BazelRuleClassProvider$StrictActionEnvOptions {
   incompatible_strict_action_env: false
 }
 FragmentOptions com.google.devtools.build.lib.bazel.rules.python.BazelPythonConfiguration$Options {
   experimental_python_import_all_repositories: true

[fmeum]

That's the effect of test trimming, which effectively removes the reference to coverage_support, which in turn affects loaded transitive packages. Perhaps the easiest fix is to move coverage_support to CoverageOptions and don't trim it.

[fmeum]

A workaround is to enable --experimental_retain_test_configuration_across_testonly, which avoids the configuration forking.