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@mbland mbland commented May 7, 2025

Description

Makes it clear that WORKSPACE users must use a target Label string with the default_config option for the scalafmt argument of scala_toolchains. Notes that the specified config file must exist within a package, including but not limited to having a BUILD file in the repository root.

Motivation

@gergelyfabian noticed this while building gergelyfabian/bazel-scala-example after #1730 landed.

This isn't fixable in code. With this call:

scala_toolchains(
    # Other toolchains...
    scalafmt = {"default_config": ".scalafmt.conf"},
)
  • scala_toolchains looks for the file under external/.scalafmt.conf.

  • Updating scala_toolchains to wrap default_config in a Label makes it relative to @rules_scala//scala. This because scala_toolchains resides in @rules_scala//scala:toolchains.bzl.

  • native.package_relative_label is only available when called from a BUILD file.

Hence default_config values under WORKSPACE must be valid target labels.

The problem doesn't exist under Bzlmod; plain file paths will work fine, so long as a BUILD file exists at the repository root.

Makes it clear that `WORKSPACE` users must use a target `Label` string
with the `default_config` option for the `scalafmt` argument of
`scala_toolchains`. Notes that the specified config file must exist
within a package, including but not limited to having a `BUILD` file in
the repository root.

---

@gergelyfabian noticed this while building
gergelyfabian/bazel-scala-example after bazel-contrib#1730 landed.

This isn't fixable in code. With this call:

```py
scala_toolchains(
    # Other toolchains...
    scalafmt = {"default_config": ".scalafmt.conf"},
)
```

- `scala_toolchains` looks for the file under `external/.scalafmt.conf`.

- Updating `scala_toolchains` to wrap `default_config` in a `Label`
  makes it relative to `@rules_scala//scala`. This because
  `scala_toolchains` resides in `@rules_scala//scala:toolchains.bzl`.

- `native.package_relative_label` is only available when called from a
  `BUILD` file.

Hence `default_config` values under `WORKSPACE` must be valid target
labels.

The problem doesn't exist under Bzlmod; plain file paths will work fine,
so long as a `BUILD` file exists at the repository root.
@mbland mbland requested review from liucijus and simuons as code owners May 7, 2025 15:14
@gergelyfabian
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Thank you!

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@simuons simuons left a comment

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Thanks

@simuons simuons merged commit f2adbac into bazel-contrib:master May 7, 2025
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@mbland mbland deleted the scalafmt-default-config-doc branch May 7, 2025 21:06
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3 participants