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:

   # //toolchains/BUILD
   load("@io_bazel_rules_scala//scala:scala_toolchain.bzl", "scala_toolchain")
   load("@io_bazel_rules_scala//scala:providers.bzl", "declare_deps_provider")
   
   scala_toolchain(
       name = "my_toolchain_impl",
       dep_providers = [
           ":my_scala_compile_classpath_provider",
           ":my_scala_library_classpath_provider",
           ":my_scala_macro_classpath_provider",
           ":my_scala_xml_provider",
           ":my_parser_combinators_provider",
       ],
       scalacopts = ["-Ywarn-unused"],
       unused_dependency_checker_mode = "off",
       visibility = ["//visibility:public"]
   )
   
   toolchain(
       name = "my_scala_toolchain",
       toolchain_type = "@io_bazel_rules_scala//scala:toolchain_type",
       toolchain = "my_toolchain_impl",
       visibility = ["//visibility:public"]
   )
   
   declare_deps_provider(
       name = "my_scala_compile_classpath_provider",
       deps_id = "scala_compile_classpath",
       visibility = ["//visibility:public"],
       deps = [
           "@io_bazel_rules_scala_scala_compiler",
           "@io_bazel_rules_scala_scala_library",
           "@io_bazel_rules_scala_scala_reflect",
       ],
   )
   
   declare_deps_provider(
       name = "my_scala_library_classpath_provider",
       deps_id = "scala_library_classpath",
       deps = [
           "@io_bazel_rules_scala_scala_library",
           "@io_bazel_rules_scala_scala_reflect",
       ],
   )
   
   declare_deps_provider(
       name = "my_scala_macro_classpath_provider",
       deps_id = "scala_macro_classpath",
       deps = [
           "@io_bazel_rules_scala_scala_library",
           "@io_bazel_rules_scala_scala_reflect",
       ],
   )
    
   declare_deps_provider(
       name = "my_scala_xml_provider",
       deps_id = "scala_xml",
       deps = ["@scala_xml_dep"],
   )
   
   declare_deps_provider(
       name = "my_parser_combinators_provider",
       deps_id = "parser_combinators",
       deps = ["@parser_combinators_dep"],
   )

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 depset 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 '-'