Expose kotlinc's -Xfriend-paths to all jvm/android kt rules under the attribute 'assocates='

.bazelci/presubmit.yml

@@ -18,7 +18,7 @@ tasks:
       - "//src/test/kotlin/io/bazel/kotlin/builder:builder_tests"
       # KotlinJvmDaggerExampleTest and KotlinJvmKaptAssertionTest are not remote
       # execution compatible, do not run them for now.
-      - "//src/test/kotlin/io/bazel/kotlin:KotlinJvmFriendsVisibilityTest"
+      - "//src/test/kotlin/io/bazel/kotlin:KotlinJvmAssociatesBasicVisibilityTest"
       - "//src/test/kotlin/io/bazel/kotlin:KotlinJvmBasicAssertionTest"
     test_flags:
       # Override the default worker strategy for remote builds (worker strategy
@@ -37,6 +37,16 @@ tasks:
       - "--override_repository=io_bazel_rules_kotlin=/tmp/rules_kotlin_release"
     test_targets:
       - //...
+  example-associates:
+    name: "Example - Associates"
+    platform: ubuntu1804
+    shell_commands:
+      - "cd ../.. && bazel build //:rules_kotlin_release && rm -rf /tmp/rules_kotlin_release && mkdir -p /tmp/rules_kotlin_release && tar -C /tmp/rules_kotlin_release -xvf bazel-bin/rules_kotlin_release.tgz"
+    working_directory: examples/associates
+    test_flags:
+      - "--override_repository=io_bazel_rules_kotlin=/tmp/rules_kotlin_release"
+    test_targets:
+      - //...
   example-anvil:
     name: "Example - Anvil"
     platform: ubuntu1804

.bazelignore

@@ -2,6 +2,7 @@
 # we don't break trying to build separate workspaces using wildcards like //...
 # examples/dagger doesn't have its own workspace, so don't do all of examples.
 examples/android
+examples/associates
 examples/jetpack_compose
 examples/node
 examples/trivial

README.md

@@ -45,8 +45,8 @@ and `kt_js`, and `kt_android` typically applied to the rules (the exception bein
 `kt_android_local_test`, which doesn't exist. Use an `android_local_test` that takes a 
 `kt_android_library` as a dependency).
 
-Limited "friend" support is available, in the form of tests being friends of their library for the
-system under test, allowing `internal` access to types and functions.
+Support for kotlin's -Xfriend-paths via the `associates=` attribute in the jvm allow access to
+`internal` members.
 
 Also, `kt_jvm_*` rules support the following standard `java_*` rules attributes:
   * `data`

examples/associates/.bazelversion

@@ -0,0 +1 @@
+../../.bazelversion

examples/associates/WORKSPACE

@@ -0,0 +1,44 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+local_repository(
+    name = "io_bazel_rules_kotlin",
+    path = "../..",
+)
+
+load("@io_bazel_rules_kotlin//kotlin:dependencies.bzl", "kt_download_local_dev_dependencies")
+
+kt_download_local_dev_dependencies()
+
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kotlin_repositories", "kt_register_toolchains")
+
+kotlin_repositories()
+
+kt_register_toolchains()
+
+RULES_JVM_EXTERNAL_TAG = "2.7"
+
+RULES_JVM_EXTERNAL_SHA = "f04b1466a00a2845106801e0c5cec96841f49ea4e7d1df88dc8e4bf31523df74"
+
+http_archive(
+    name = "rules_jvm_external",
+    sha256 = RULES_JVM_EXTERNAL_SHA,
+    strip_prefix = "rules_jvm_external-%s" % RULES_JVM_EXTERNAL_TAG,
+    url = "https://github.com/bazelbuild/rules_jvm_external/archive/%s.zip" % RULES_JVM_EXTERNAL_TAG,
+)
+
+load("@rules_jvm_external//:defs.bzl", "maven_install")
+
+maven_install(
+    artifacts = [
+        "junit:junit:4.13",
+    ],
+    repositories = [
+        "https://repo1.maven.org/maven2",
+    ],
+)
+
+http_archive(
+    name = "rules_pkg",
+    sha256 = "4ba8f4ab0ff85f2484287ab06c0d871dcb31cc54d439457d28fd4ae14b18450a",
+    url = "https://github.com/bazelbuild/rules_pkg/releases/download/0.2.4/rules_pkg-0.2.4.tar.gz",
+)

examples/associates/projects/core/api/BUILD.bazel

@@ -0,0 +1,9 @@
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_jvm_library")
+
+package(default_visibility = ["//visibility:public"])
+
+kt_jvm_library(
+    name = "api",
+    srcs = glob(["src/main/kotlin/**/*.kt"]),
+    deps = [],
+)

examples/associates/projects/core/api/src/main/kotlin/core/api/api.kt

@@ -0,0 +1,16 @@
+package core.api
+
+interface SomeInterface {
+  val name: String
+  val camelName: String
+}
+
+data class MyType(
+  override val name: String
+) : SomeInterface {
+  override val camelName: String = name.camelCase()
+}
+
+internal fun String.camelCase() = this.split("_").joinToString("") {
+  "${it[0].toUpperCase()}${it.substring(1)}"
+}

examples/associates/projects/core/api/src/test/kotlin/core/api/BUILD.bazel

@@ -0,0 +1,10 @@
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_jvm_test")
+
+kt_jvm_test(
+    name = "CoreApiTest",
+    srcs = ["CoreApiTest.kt"],
+    friends = ["//projects/core/api"],  # Deprecated - here to ensure it still works.
+    deps = [
+        "@maven//:junit_junit",
+    ],
+)

examples/associates/projects/core/api/src/test/kotlin/core/api/CoreApiTest.kt

@@ -0,0 +1,15 @@
+package core.api
+
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class CoreApiTest {
+  @Test fun testCamelCaseVar() {
+    val foo = MyType("foo_bar")
+    assertEquals("FooBar", foo.camelName)
+  }
+
+  @Test fun testCamelCaseFun() {
+    assertEquals("FooBar", "foo_bar".camelCase())
+  }
+}

examples/associates/projects/core/impl/BUILD.bazel

@@ -0,0 +1,13 @@
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_jvm_library")
+
+kt_jvm_library(
+    name = "impl",
+    srcs = glob(["src/main/kotlin/**/*.kt"]),
+    associates = ["//projects/core/api"],
+    visibility = [
+        "//projects/core:__subpackages__",
+    ],
+    deps = [
+        # All my deps are associates.
+    ],
+)

examples/associates/projects/core/impl/src/main/kotlin/core/impl/impl.kt

@@ -0,0 +1,13 @@
+package core.impl
+
+import core.api.SomeInterface
+import core.api.camelCase
+
+internal data class ImplType(
+  override val name: String
+) : SomeInterface {
+  override val camelName: String = name.camelCase()
+  val customName = name.customStuff()
+}
+
+internal fun String.customStuff() = "${hashCode()}"

examples/associates/projects/core/impl/src/test/kotlin/core/impl/BUILD.bazel

@@ -0,0 +1,13 @@
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_jvm_test")
+
+kt_jvm_test(
+    name = "CoreImplTest",
+    srcs = ["CoreImplTest.kt"],
+    associates = [
+        "//projects/core/api",
+        "//projects/core/impl",
+    ],
+    deps = [
+        "@maven//:junit_junit",
+    ],
+)

examples/associates/projects/core/impl/src/test/kotlin/core/impl/CoreImplTest.kt

@@ -0,0 +1,17 @@
+package core.impl
+
+import core.api.camelCase
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class CoreImplTest {
+  @Test fun testCamelCaseVar() {
+    val foo = ImplType("foo_bar")
+    assertEquals("FooBar", foo.camelName)
+  }
+
+  @Test fun testCamelCaseFun() {
+    // Testing transitivity here. TODO: Once strict deps are in place, delete this case.
+    assertEquals("FooBar", "foo_bar".camelCase())
+  }
+}

kotlin/internal/defs.bzl

@@ -25,6 +25,7 @@ KT_COMPILER_REPO = "com_github_jetbrains_kotlin"
 KtJvmInfo = provider(
     fields = {
         "module_name": "the module name",
+        "module_jars": "Jars comprising the module (logical compilation unit), a.k.a. associates",
         "exported_compiler_plugins": "compiler plugins to be invoked by targets depending on this.",
         "srcs": "the source files. [intelij-aspect]",
         "outputs": "output jars produced by this rule. [intelij-aspect]",

kotlin/internal/jvm/android.bzl

@@ -18,7 +18,17 @@ load(
 
 _ANDROID_SDK_JAR = "%s" % Label("//third_party:android_sdk")
 
-def _kt_android_artifact(name, srcs = [], deps = [], plugins = [], friends = [], kotlinc_opts = None, javac_opts = None, enable_data_binding = False, **kwargs):
+def _kt_android_artifact(
+        name,
+        srcs = [],
+        deps = [],
+        plugins = [],
+        friends = None,
+        associates = [],
+        kotlinc_opts = None,
+        javac_opts = None,
+        enable_data_binding = False,
+        **kwargs):
     """Delegates Android related build attributes to the native rules but uses the Kotlin builder to compile Java and
     Kotlin srcs. Returns a sequence of labels that a wrapping macro should export.
     """
@@ -42,6 +52,7 @@ def _kt_android_artifact(name, srcs = [], deps = [], plugins = [], friends = [],
         deps = base_deps + [base_name],
         plugins = plugins,
         friends = friends,
+        associates = associates,
         testonly = kwargs.get("testonly", default = False),
         visibility = ["//visibility:private"],
         kotlinc_opts = kotlinc_opts,

kotlin/internal/jvm/associates.bzl

@@ -0,0 +1,83 @@
+# Copyright 2020 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+load(
+    "//kotlin/internal:defs.bzl",
+    _KtJvmInfo = "KtJvmInfo",
+)
+load(
+    "//kotlin/internal/utils:sets.bzl",
+    _sets = "sets",
+)
+load(
+    "//kotlin/internal/utils:utils.bzl",
+    _utils = "utils",
+)
+
+def _get_associates(ctx):
+    """Creates a struct of associates meta data"""
+
+    friends_legacy = getattr(ctx.attr, "friends", [])
+    associates = getattr(ctx.attr, "associates", [])
+
+    if friends_legacy:
+        print("WARNING: friends=[...] is deprecated, please prefer associates=[...] instead.")
+        if associates:
+            fail("friends= may not be used together with associates=. Use one or the other.")
+        elif ctx.attr.testonly == False:
+            fail("Only testonly targets can use the friends attribute. ")
+        else:
+            associates = friends_legacy
+
+    if not bool(associates):
+        return struct(
+            targets = [],
+            module_name = _utils.derive_module_name(ctx),
+            jars = [],
+        )
+    elif ctx.attr.module_name:
+        fail("if associates have been set then module_name cannot be provided")
+    else:
+        jars = [depset([a], transitive = a[_KtJvmInfo].module_jars) for a in associates]
+        module_names = _sets.copy_of([x[_KtJvmInfo].module_name for x in associates])
+        if len(module_names) > 1:
+            fail("Dependencies from several different kotlin modules cannot be associated. " +
+                 "Associates can see each other's \"internal\" members, and so must only be " +
+                 "used with other targets in the same module: \n%s" % module_names)
+        if len(module_names) < 1:
+            # This should be impossible
+            fail("Error in rules - a KtJvmInfo was found which did not have a module_name")
+        return struct(
+            targets = associates,
+            jars = jars,
+            module_name = list(module_names)[0],
+        )
+
+def _flatten_jars(nested_jars_depset):
+    """Returns a list of strings containing the compile_jars for depset of targets.
+
+    This ends up unwinding the nesting of depsets, since compile_jars contains depsets inside
+    the nested_jars targets, which themselves are depsets.  This function is intended to be called
+    lazily form within Args.add_all(map_each) as it collapses depsets.
+    """
+    compile_jars_depsets = [
+        target[JavaInfo].compile_jars
+        for target in nested_jars_depset.to_list()
+        if target[JavaInfo].compile_jars
+    ]
+    return [file.path for file in depset(transitive = compile_jars_depsets).to_list()]
+
+associate_utils = struct(
+    get_associates = _get_associates,
+    flatten_jars = _flatten_jars,
+)