List index out of range while loading BSP metadata

[stuhood]

Describe the bug

  File "$HOME/.cache/pants/setup/bootstrap-Darwin-x86_64/2.12.0.dev3_py39/lib/python3.9/site-packages/pants/bsp/util_rules/targets.py", line 368, in generate_one_bsp_build_target_request
    metadata = metadata_results_by_lang_id[metadata_merge_order[-1].language_id].metadata
IndexError: list index out of range

Pants version
2.12.0.dev3

Additional info

# bsp-groups.toml
[groups.default]
addresses = [
  "src/jvm::",
  "tests/jvm::",
]
resolve = "jvm:jvm-default"

[tdyas]

Seems to occur with tests/jvm:: and BSP works fine if that glob is removed.

[tdyas]

I also saw the following error on another occasion of adding tests/jvm:: to the example-jvm BSP config file:

org.eclipse.lsp4j.jsonrpc.ResponseErrorException: pants.source.source_root.NoSourceRootError: No source root found for `tests/jvm/org/pantsbuild/example/lib/ExampleLibSpec.scala`. See https://www.pantsbuild.org/v2.12/docs/source-roots for how to define source roots.

[stuhood]

I also saw the following error on another occasion of adding tests/jvm:: to the example-jvm BSP config file:

org.eclipse.lsp4j.jsonrpc.ResponseErrorException: pants.source.source_root.NoSourceRootError: No source root found for `tests/jvm/org/pantsbuild/example/lib/ExampleLibSpec.scala`. See https://www.pantsbuild.org/v2.12/docs/source-roots for how to define source roots.

That one is addressed in pantsbuild/example-jvm#15 by adding the source root to pants.toml.

[stuhood]

Seems to occur with tests/jvm:: and BSP works fine if that glob is removed.

AFAICT, there is some amount of caching of the BSP protocol state in IntelliJ. Clicking:

...to stop the connection, and then refreshing in:

...seems to reliably get me errors.

---

The underlying cause of having an empty list here might be a bug in #15064: targets with a default resolve don't match anything. Will fix both issues.