scala_toolchain.md

scala_toolchain

scala_toolchain allows you to define global configuration to all Scala targets.

Some scala_toolchain must be registered!

Several options to configure scala_toolchain:

A) Use the default scala_toolchain:

In your workspace file add the following lines:

# WORKSPACE
# register default scala toolchain
load("@io_bazel_rules_scala//scala:toolchains.bzl", "scala_register_toolchains")
scala_register_toolchains()

B) Defining your own scala_toolchain requires 2 steps:

1. Add your own definition of scala_toolchain to a BUILD file: Example assumes external libraries are resolved with rules_jvm_external

   # //toolchains/BUILD
   load("//scala:scala.bzl", "setup_scala_toolchain")
   
   setup_scala_toolchain(
       name = "my_toolchain",
       # configure toolchain dependecies
       parser_combinators_deps = [
           "@maven//:org_scala_lang_modules_scala_parser_combinators_2_12",
       ],
       scala_compile_classpath = [
           "@maven//:org_scala_lang_scala_compiler",
           "@maven//:org_scala_lang_scala_library",
           "@maven//:org_scala_lang_scala_reflect",
       ],
       scala_library_classpath = [
           "@maven//:org_scala_lang_scala_library",
           "@maven//:org_scala_lang_scala_reflect",
       ],
       scala_macro_classpath = [
           "@maven//:org_scala_lang_scala_library",
           "@maven//:org_scala_lang_scala_reflect",
       ],
       scala_xml_deps = [
           "@maven//:org_scala_lang_modules_scala_xml_2_12",
       ],
       # example of setting attribute values
       scalacopts = ["-Ywarn-unused"],
       unused_dependency_checker_mode = "off",
       visibility = ["//visibility:public"]
   )

2. Register your custom toolchain from WORKSPACE:

   # WORKSPACE
   register_toolchains("//toolchains:my_scala_toolchain")

Attributes
dep_providers	List of labels; optional Allows to configure dependencies lists by configuring DepInfo provider targets. Currently supported dep ids: scala_compile_classpath, scala_library_classpath, scala_macro_classpath, scala_xml, parser_combinators.
scalacopts	List of strings; optional Extra compiler options for this binary to be passed to scalac.
scalac_jvm_flags	List of strings; optional List of JVM flags to be passed to scalac. For example ["-Xmx5G"] could be passed to control memory usage of Scalac. This is overridden by the scalac_jvm_flags attribute on individual targets.
scala_test_jvm_flags	List of strings; optional List of JVM flags to be passed to the ScalaTest runner. For example ["-Xmx5G"] could be passed to control memory usage of the ScalaTest runner. This is overridden by the jvm_flags attribute on individual targets.
unused_dependency_checker_mode	String; optional Enable unused dependency checking (see Unused dependency checking). Possible values are: off, warn and error.
dependency_tracking_strict_deps_patterns	List of Strings; optional List of target prefixes included for strict deps analysis. Exclude patetrns with '-'
dependency_tracking_unused_deps_patterns	List of Strings; optional List of target prefixes included for unused deps analysis. Exclude patetrns with '-'