Move resolved_toolchain into the main workspace (bazelbuild#48)

mylang/BUILD.bazel

@@ -1,4 +1,5 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+load("//mylang/private:resolved_toolchain.bzl", "resolved_toolchain")
 
 # For stardoc to reference the files
 exports_files(["defs.bzl"])
@@ -11,6 +12,14 @@ toolchain_type(
     visibility = ["//visibility:public"],
 )
 
+resolved_toolchain(
+    name = "resolved_toolchain",
+    # Marked manual so that `bazel test //...` passes
+    # even if no toolchain is registered.
+    tags = ["manual"],
+    visibility = ["//visibility:public"],
+)
+
 bzl_library(
     name = "repositories",
     srcs = ["repositories.bzl"],

mylang/private/BUILD.bazel

@@ -11,3 +11,9 @@ bzl_library(
     srcs = ["versions.bzl"],
     visibility = ["//mylang:__subpackages__"],
 )
+
+bzl_library(
+    name = "resolved_toolchain",
+    srcs = ["resolved_toolchain.bzl"],
+    visibility = ["//mylang:__subpackages__"],
+)

mylang/private/resolved_toolchain.bzl

@@ -0,0 +1,27 @@
+"""This module implements an alias rule to the resolved toolchain.
+"""
+
+DOC = """\
+Exposes a concrete toolchain which is the result of Bazel resolving the
+toolchain for the execution or target platform.
+Workaround for https://github.com/bazelbuild/bazel/issues/14009
+"""
+
+# Forward all the providers
+def _resolved_toolchain_impl(ctx):
+    toolchain_info = ctx.toolchains["//mylang:toolchain_type"]
+    return [
+        toolchain_info,
+        toolchain_info.default,
+        toolchain_info.mylanginfo,
+        toolchain_info.template_variables,
+    ]
+
+# Copied from java_toolchain_alias
+# https://cs.opensource.google/bazel/bazel/+/master:tools/jdk/java_toolchain_alias.bzl
+resolved_toolchain = rule(
+    implementation = _resolved_toolchain_impl,
+    toolchains = ["//mylang:toolchain_type"],
+    incompatible_use_toolchain_transition = True,
+    doc = DOC,
+)

mylang/private/toolchains_repo.bzl

@@ -47,41 +47,12 @@ PLATFORMS = {
 }
 
 def _toolchains_repo_impl(repository_ctx):
-    # Expose a concrete toolchain which is the result of Bazel resolving the toolchain
-    # for the execution or target platform.
-    # Workaround for https://github.com/bazelbuild/bazel/issues/14009
-    starlark_content = """# Generated by toolchains_repo.bzl
-
-# Forward all the providers
-def _resolved_toolchain_impl(ctx):
-    toolchain_info = ctx.toolchains["@com_myorg_rules_mylang//mylang:toolchain_type"]
-    return [
-        toolchain_info,
-        toolchain_info.default,
-        toolchain_info.mylanginfo,
-        toolchain_info.template_variables,
-    ]
-
-# Copied from java_toolchain_alias
-# https://cs.opensource.google/bazel/bazel/+/master:tools/jdk/java_toolchain_alias.bzl
-resolved_toolchain = rule(
-    implementation = _resolved_toolchain_impl,
-    toolchains = ["@com_myorg_rules_mylang//mylang:toolchain_type"],
-    incompatible_use_toolchain_transition = True,
-)
-"""
-    repository_ctx.file("defs.bzl", starlark_content)
-
     build_content = """# Generated by toolchains_repo.bzl
 #
 # These can be registered in the workspace file or passed to --extra_toolchains flag.
 # By default all these toolchains are registered by the mylang_register_toolchains macro
 # so you don't normally need to interact with these targets.
 
-load(":defs.bzl", "resolved_toolchain")
-
-resolved_toolchain(name = "resolved_toolchain", visibility = ["//visibility:public"])
-
 """
 
     for [platform, meta] in PLATFORMS.items():