Add support for Kotlin JARs with inlined functions, and an Android Kotlin example app

.bazelci/examples.yml

@@ -38,8 +38,6 @@ tasks:
     working_directory: examples/android_instrumentation_test
     # Android instrumentation tests don't work on Windows yet.
     build_targets:
-      - "//src/main:greeter_app"
-      - "//src/test:greeter_test_app"
   android-local-test-linux:
     name: "Android Robolectric test example"
     platform: ubuntu1804
@@ -60,3 +58,24 @@ tasks:
     # See https://github.com/bazelbuild/bazel/issues/7809
     build_targets:
       - "//..."
+  android-kotlin-linux:
+    name: "Android Kotlin example"
+    platform: ubuntu1804
+    working_directory: examples/android_kotlin_app
+    build_targets:
+    - "//:app"
+  android-kotlin-macos:
+    name: "Android Kotlin example"
+    platform: macos
+    working_directory: examples/android_kotlin_app
+    build_targets:
+    - "//:app"
+  # rules_kotlin does not work on Windows.
+  # https://github.com/bazelbuild/rules_kotlin/issues/179
+  # https://github.com/bazelbuild/rules_kotlin/blob/master/.bazelci/presubmit.yml
+  # android-kotlin-windows:
+  #   name: "Android Kotlin example"
+  #   platform: windows
+  #   working_directory: examples/android_kotlin_app
+  #   build_targets:
+  #   - "//:app"

.bazelci/presubmit.yml

@@ -44,4 +44,9 @@ platforms:
     # TODO(jin): fix long paths issue on Windows
     # - "//examples:app"
     test_targets:
+    - "--"
     - "//tests/unit/..."
+    # rules_kotlin is not tested / does not work on Windows.
+    # https://github.com/bazelbuild/rules_kotlin/issues/179
+    # https://github.com/bazelbuild/rules_kotlin/blob/master/.bazelci/presubmit.yml
+    - "-//tests/unit/kotlin/..."

WORKSPACE

@@ -89,6 +89,17 @@ maven_install(
     use_unsafe_shared_cache = True,
 )
 
+maven_install(
+    name = "kotlin_tests",
+    artifacts = [
+        "junit:junit:4.12",
+        "org.jetbrains.kotlin:kotlin-test:1.3.21",
+    ],
+    repositories = [
+        "https://repo1.maven.org/maven2",
+    ],
+)
+
 # These artifacts helped discover limitations by the Maven resolver. Each
 # artifact listed here *must have* an accompanying issue. We build_test these
 # targets to ensure that they remain supported by the rule.
@@ -104,14 +115,32 @@ maven_install(
     ],
 )
 
+RULES_KOTLIN_VERSION = "da1232eda2ef90d4375e2d1677b32c7ddf09e8a1"
+
+http_archive(
+    name = "io_bazel_rules_kotlin",
+    sha256 = "0bbb0e5e536f0c775f37bded59d4f8cfb8556e6c3d926fcc0f58bf3489bff470",
+    strip_prefix = "rules_kotlin-%s" % RULES_KOTLIN_VERSION,
+    url = "https://github.com/bazelbuild/rules_kotlin/archive/%s.tar.gz" % RULES_KOTLIN_VERSION,
+)
+
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kotlin_repositories", "kt_register_toolchains")
+
+kotlin_repositories()
+
+kt_register_toolchains()
+
 BAZEL_SKYLIB_TAG = "0.7.0"
+
 http_archive(
     name = "bazel_skylib",
+    sha256 = "2c62d8cd4ab1e65c08647eb4afe38f51591f43f7f0885e7769832fa137633dcb",
     strip_prefix = "bazel-skylib-%s" % BAZEL_SKYLIB_TAG,
     url = "https://github.com/bazelbuild/bazel-skylib/archive/%s.tar.gz" % BAZEL_SKYLIB_TAG,
-    sha256 = "2c62d8cd4ab1e65c08647eb4afe38f51591f43f7f0885e7769832fa137633dcb",
 )
+
 load("@bazel_skylib//:workspace.bzl", "bazel_skylib_workspace")
+
 bazel_skylib_workspace()
 
 # End test dependencies

coursier.bzl

@@ -16,6 +16,9 @@ load("//:specs.bzl", "parse", "utils")
 
 _BUILD = """
 package(default_visibility = ["//visibility:public"])
+
+load("@{repository_name}//:jvm_import.bzl", "jvm_import")
+
 {imports}
 """
 
@@ -73,16 +76,17 @@ def _relativize_and_symlink_file(repository_ctx, absolute_path):
 # Get the reverse dependencies of an artifact from the Coursier parsed
 # dependency tree.
 def _get_reverse_deps(coord, dep_tree):
-  reverse_deps = []
-  # For all potential reverse dep artifacts,
-  for maybe_rdep in dep_tree["dependencies"]:
-      # For all dependencies of this artifact,
-      for maybe_rdep_coord in maybe_rdep["dependencies"]:
-          # If this artifact depends on the missing artifact,
-          if maybe_rdep_coord == coord:
-              # Then this artifact is an rdep :-)
-              reverse_deps.append(maybe_rdep)
-  return reverse_deps
+    reverse_deps = []
+
+    # For all potential reverse dep artifacts,
+    for maybe_rdep in dep_tree["dependencies"]:
+        # For all dependencies of this artifact,
+        for maybe_rdep_coord in maybe_rdep["dependencies"]:
+            # If this artifact depends on the missing artifact,
+            if maybe_rdep_coord == coord:
+                # Then this artifact is an rdep :-)
+                reverse_deps.append(maybe_rdep)
+    return reverse_deps
 
 # Generate BUILD file with java_import and aar_import for each artifact in
 # the transitive closure, with their respective deps mapped to the resolved
@@ -154,7 +158,10 @@ def generate_imports(repository_ctx, dep_tree, srcs_dep_tree = None):
             #
             packaging = artifact_relative_path.split(".").pop()
             if packaging == "jar":
-                target_import_string = ["java_import("]
+                # Regular `java_import` invokes ijar on all JARs, causing some Scala and
+                # Kotlin compile interface JARs to be incorrect. We replace java_import
+                # with a simple jvm_import Starlark rule that skips ijar.
+                target_import_string = ["jvm_import("]
             elif packaging == "aar":
                 target_import_string = ["aar_import("]
             else:
@@ -382,7 +389,7 @@ def _coursier_fetch_impl(repository_ctx):
     cmd = _generate_coursier_command(repository_ctx)
     cmd.extend(["fetch"])
     cmd.extend(artifact_coordinates)
-    cmd.extend(["--artifact-type", ",".join(_COURSIER_PACKAGING_TYPES)])
+    cmd.extend(["--artifact-type", ",".join(_COURSIER_PACKAGING_TYPES + ["src"])])
     cmd.append("--quiet")
     cmd.append("--no-default")
     cmd.extend(["--json-output-file", "dep-tree.json"])
@@ -439,9 +446,19 @@ def _coursier_fetch_impl(repository_ctx):
         srcs_dep_tree = srcs_dep_tree,
     )
 
+    repository_ctx.template(
+        "jvm_import.bzl",
+        repository_ctx.attr._jvm_import,
+        substitutions = {},
+        executable = False,  # not executable
+    )
+
     repository_ctx.file(
         "BUILD",
-        _BUILD.format(imports = generated_imports),
+        _BUILD.format(
+            repository_name = repository_ctx.name,
+            imports = generated_imports,
+        ),
         False,  # not executable
     )
 
@@ -457,7 +474,10 @@ def _coursier_fetch_impl(repository_ctx):
 
 coursier_fetch = repository_rule(
     attrs = {
-        "_coursier": attr.label(default = "//:third_party/coursier/coursier"),  # vendor coursier, it's just a jar
+        "_coursier": attr.label(
+            default = "//:third_party/coursier/coursier",
+        ),  # vendor coursier, it's just a jar
+        "_jvm_import": attr.label(default = "//:private/jvm_import.bzl"),
         "repositories": attr.string_list(),  # list of repository objects, each as json
         "artifacts": attr.string_list(),  # list of artifact objects, each as json
         "fetch_sources": attr.bool(default = False),

examples/android_kotlin_app/AndroidManifest.xml

@@ -0,0 +1,10 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.example.bazel"
+          android:versionCode="1"
+          android:versionName="1.0">
+
+    <uses-sdk
+        android:minSdkVersion="21"
+        android:targetSdkVersion="26" />
+
+</manifest>

examples/android_kotlin_app/BUILD

@@ -0,0 +1,8 @@
+android_binary(
+    name = "app",
+    manifest = "AndroidManifest.xml",
+    custom_package = "com.example.bazel",
+    deps = [
+        "//src:lib",
+    ],
+)

examples/android_kotlin_app/WORKSPACE

@@ -0,0 +1,37 @@
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+
+android_sdk_repository(name = "androidsdk")
+
+# BEGIN io_bazel_rules_kotlin
+
+RULES_KOTLIN_VERSION = "da1232eda2ef90d4375e2d1677b32c7ddf09e8a1"
+http_archive(
+    name = "io_bazel_rules_kotlin",
+    strip_prefix = "rules_kotlin-%s" % RULES_KOTLIN_VERSION,
+    url = "https://github.com/bazelbuild/rules_kotlin/archive/%s.tar.gz" % RULES_KOTLIN_VERSION,
+    sha256 = "0bbb0e5e536f0c775f37bded59d4f8cfb8556e6c3d926fcc0f58bf3489bff470",
+)
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kotlin_repositories", "kt_register_toolchains")
+
+kotlin_repositories()
+kt_register_toolchains()
+
+# END io_bazel_rules_kotlin
+
+local_repository(
+    name = "rules_jvm_external",
+    path = "../../",
+)
+
+load("@rules_jvm_external//:defs.bzl", "maven_install")
+
+maven_install(
+    artifacts = [
+        "androidx.appcompat:appcompat:1.0.2",
+        "androidx.core:core-ktx:1.0.1",
+    ],
+    repositories = [
+        "https://maven.google.com",
+        "https://repo1.maven.org/maven2",
+    ],
+)

examples/android_kotlin_app/src/AndroidManifest.xml

@@ -0,0 +1,22 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+          package="com.example.bazel"
+          android:versionCode="1"
+          android:versionName="1.0" >
+
+    <uses-sdk
+        android:minSdkVersion="21"
+        android:targetSdkVersion="26" />
+
+    <application
+        android:label="rules_jvm_external Kotlin App">
+        <activity
+            android:name=".MainActivity"
+            android:theme="@style/AppTheme"
+            android:label="rules_jvm_external Kotlin App">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>

examples/android_kotlin_app/src/BUILD

@@ -0,0 +1,20 @@
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_android_library")
+load("@rules_jvm_external//:defs.bzl", "artifact")
+
+kt_android_library(
+    name = "lib",
+    srcs = glob(["java/com/example/bazel/*.kt"]),
+    manifest = "AndroidManifest.xml",
+    custom_package = "com.example.bazel",
+    resource_files = glob(["res/**"]),
+    deps = [
+        "@maven//:androidx_appcompat_appcompat",
+        "@maven//:androidx_core_core",
+        "@maven//:androidx_core_core_ktx",
+        "@maven//:androidx_drawerlayout_drawerlayout",
+        "@maven//:androidx_fragment_fragment",
+        "@maven//:androidx_lifecycle_lifecycle_common",
+        "@maven//:androidx_lifecycle_lifecycle_viewmodel",
+    ],
+    visibility = ["//:__pkg__"]
+)

examples/android_kotlin_app/src/java/com/example/bazel/MainActivity.kt

@@ -0,0 +1,13 @@
+package com.example.bazel
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+
+class MainActivity : AppCompatActivity() {
+
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    this.setContentView(R.layout.activity_main)
+  }
+
+}

examples/android_kotlin_app/src/res/layout/activity_main.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+             xmlns:tools="http://schemas.android.com/tools"
+             android:id="@+id/container"
+             android:layout_width="match_parent"
+             android:layout_height="match_parent"
+             tools:context=".MainActivity"
+             tools:ignore="MergeRootFrame,UnusedIds" />

examples/android_kotlin_app/src/res/values/styles.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+
+    <!-- Base application theme. -->
+    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
+        <!--&lt;!&ndash; Customize your theme here. &ndash;&gt;-->
+    </style>
+
+</resources>

private/jvm_import.bzl

@@ -0,0 +1,55 @@
+# Stripped down version of a java_import Starlark rule, without invoking ijar
+# to create interface jars.
+
+# Inspired by Square's implementation of `raw_jvm_import` [0] and discussions
+# on the GitHub thread [1] about ijar's interaction with Kotlin JARs.
+#
+# [0]: https://github.com/square/bazel_maven_repository/pull/48
+# [1]: https://github.com/bazelbuild/bazel/issues/4549
+
+
+def _jvm_import_impl(ctx):
+  if len(ctx.files.jars) != 1:
+    fail("Please only specify one jar to import in the jars attribute.")
+
+  return [
+      DefaultInfo(
+          files = depset(ctx.files.jars)
+      ),
+      JavaInfo(
+          compile_jar = ctx.files.jars[0],
+          output_jar = ctx.files.jars[0],
+          source_jar = ctx.file.srcjar,
+          deps = [
+              dep[JavaInfo]
+              for dep
+              in ctx.attr.deps
+              if JavaInfo in dep
+          ],
+      )
+  ]
+
+
+jvm_import = rule(
+    attrs={
+        "jars":
+            attr.label_list(
+                allow_files=True,
+                mandatory=True,
+                cfg="target",
+            ),
+        "srcjar":
+            attr.label(
+                allow_single_file=True,
+                mandatory=False,
+                cfg="target",
+            ),
+        "deps":
+            attr.label_list(
+                default=[],
+                providers=[JavaInfo],
+            ),
+    },
+    implementation=_jvm_import_impl,
+    provides=[JavaInfo],
+)

tests/unit/kotlin/BUILD

@@ -0,0 +1,11 @@
+load("@io_bazel_rules_kotlin//kotlin:kotlin.bzl", "kt_jvm_test")
+
+kt_jvm_test(
+    name = "inline_function_test",
+    srcs = ["com/example/bazel/InlineFunctionTest.kt"],
+    test_class = "com.example.bazel.InlineFunctionTest",
+    deps = [
+        "@kotlin_tests//:junit_junit",
+        "@kotlin_tests//:org_jetbrains_kotlin_kotlin_test",
+    ]
+)