Made the default toolchain configurable

WORKSPACE

@@ -119,7 +119,7 @@ load("@annex//:defs.bzl", annex_pinned_maven_install = "pinned_maven_install")
 
 annex_pinned_maven_install()
 
-scala_register_toolchains()
+scala_register_toolchains(default_scala_toolchain_name = "zinc_2_13")
 
 #  Scala 2.12
 

rules/register_toolchain.bzl

@@ -188,7 +188,7 @@ def _make_register_toolchain(configuration_rule):
         native.config_setting(
             name = "{}-setting".format(name),
             flag_values = {
-                "@rules_scala_annex//rules/scala:scala-toolchain": name,
+                "@rules_scala_annex_scala_toolchain//:scala-toolchain": name,
             },
         )
 
@@ -210,13 +210,13 @@ def _scala_toolchain_transition_impl(_, attr):
         return {}
 
     return {
-        "//rules/scala:scala-toolchain": attr.scala_toolchain_name,
+        "@rules_scala_annex_scala_toolchain//:scala-toolchain": attr.scala_toolchain_name,
     }
 
 scala_toolchain_transition = transition(
     implementation = _scala_toolchain_transition_impl,
     inputs = [],
-    outputs = ["//rules/scala:scala-toolchain"],
+    outputs = ["@rules_scala_annex_scala_toolchain//:scala-toolchain"],
 )
 
 scala_toolchain_transition_attributes = {

rules/scala/BUILD

@@ -1,17 +1,9 @@
-load("@bazel_skylib//rules:common_settings.bzl", "string_setting")
-
 filegroup(
     name = "bzl",
     srcs = glob(["**/*.bzl"]),
     visibility = ["//rules:__pkg__"],
 )
 
-string_setting(
-    name = "scala-toolchain",
-    build_setting_default = "zinc_3",
-    visibility = ["//visibility:public"],
-)
-
 toolchain_type(
     name = "toolchain_type",
     visibility = ["//visibility:public"],

rules/scala/workspace.bzl

@@ -79,11 +79,38 @@ def scala_repositories(
         ],
     )
 
-def scala_register_toolchains(*args):
+def _toolchain_configuration_repository_impl(repository_ctx):
+    repository_ctx.file(
+        "BUILD",
+        """\
+load("@bazel_skylib//rules:common_settings.bzl", "string_setting")
+
+string_setting(
+    name = "scala-toolchain",
+    build_setting_default = "{}",
+    visibility = ["//visibility:public"],
+)
+""".format(repository_ctx.attr.default_scala_toolchain_name),
+    )
+
+_toolchain_configuration_repository = repository_rule(
+    attrs = {
+        "default_scala_toolchain_name": attr.string(mandatory = True),
+    },
+    doc = "Defines a setting for the Scala toolchain to use. This is done in a separate repository so we can provide the default dynamically.",
+    implementation = _toolchain_configuration_repository_impl,
+)
+
+def scala_register_toolchains(default_scala_toolchain_name, toolchains = []):
+    _toolchain_configuration_repository(
+        name = "rules_scala_annex_scala_toolchain",
+        default_scala_toolchain_name = default_scala_toolchain_name,
+    )
+
     native.register_toolchains(
         "//src/main/scala:bootstrap_2_13",
         "//src/main/scala:bootstrap_3",
         "//src/main/scala:zinc_2_13",
         "//src/main/scala:zinc_3",
-        *args,
+        *toolchains
     )

tests/WORKSPACE

@@ -94,17 +94,20 @@ load("@annex//:defs.bzl", annex_pinned_maven_install = "pinned_maven_install")
 annex_pinned_maven_install()
 
 scala_register_toolchains(
-    "@@//dependencies/indirect:test_zinc_2_13_direct_deps_off",
-    "@@//dependencies/indirect:test_zinc_2_13_used_deps_off",
-    "@@//plugins/kind-projector:test_zinc_2_13_with_kind_projector",
-    "@@//scala:test_bootstrap_2_12",
-    "@@//scala:test_bootstrap_2_13",
-    "@@//scala:test_bootstrap_3",
-    "@@//scala:test_zinc_2_12",
-    "@@//scala:test_zinc_2_13",
-    "@@//scala:test_zinc_3",
-    "@@//scala:test_zinc_2_13_fatal_deprecation_opt",
-    "@@//scala:test_zinc_2_13_log_level_debug",
+    default_scala_toolchain_name = "test_zinc_2_13",
+    toolchains = [
+        "@@//dependencies/indirect:test_zinc_2_13_direct_deps_off",
+        "@@//dependencies/indirect:test_zinc_2_13_used_deps_off",
+        "@@//plugins/kind-projector:test_zinc_2_13_with_kind_projector",
+        "@@//scala:test_bootstrap_2_12",
+        "@@//scala:test_bootstrap_2_13",
+        "@@//scala:test_bootstrap_3",
+        "@@//scala:test_zinc_2_12",
+        "@@//scala:test_zinc_2_13",
+        "@@//scala:test_zinc_3",
+        "@@//scala:test_zinc_2_13_fatal_deprecation_opt",
+        "@@//scala:test_zinc_2_13_log_level_debug",
+    ],
 )
 
 #  Scala 2.12