A phase extension phase_scalafmt can format Scala source code via Scalafmt.
Add this snippet to WORKSPACE
load("//scala/scalafmt:scalafmt_repositories.bzl", "scalafmt_default_config", "scalafmt_repositories")
scalafmt_default_config()
scalafmt_repositories()
To add this phase to a rule, you have to pass the extension to a rule macro. Take scala_binary for example,
load("//scala:advanced_usage/scala.bzl", "make_scala_binary")
load("//scala/scalafmt:phase_scalafmt_ext.bzl", "ext_scalafmt")
scalafmt_scala_binary = make_scala_binary(ext_scalafmt)
Then use scalafmt_scala_binary as normal.
The extension adds 2 additional attributes to the rule
format: enable formattingconfig: the Scalafmt configuration file
When format is set to true, you can do
bazel run <TARGET>.format
to format the source code, and do
bazel run <TARGET>.format-test
to check the format (without modifying source code).
The extension provides default configuration, but there are 2 ways to use custom configuration
- Put
.scalafmt.confat root of your workspace - Pass
.scalafmt.confin viaconfigattribute
If using scala 3 you must append runner.dialect = scala3 to .scalafmt.conf
If you use IntelliJ Bazel plugin, then you should check the Customizable Phase page.
TL;DR: you should try naming your scalafmt rules the same way as the default rules_scala rules are named (in your own
scope), otherwise external dependency loading won't work in IntelliJ for your Scala targets. E.g.:
# Using this rule won't let you see external dependencies:
scalafmt_scala_binary = make_scala_binary(ext_scalafmt)
# But this will work:
scala_binary = make_scala_binary(ext_scalafmt)