More accurate core library desugaring support

The main idea is to use a custom wrapper around Animal Sniffer (instead of the Gradle plugin) so that we can 

* change class names in signatures, e.g. `DesugarDate` -> `Date`
* relax the superclass validation when merging signatures (i.e. we don't care whether `Long8` extends `Object` or `Number` but Animal Sniffer normally does)

Additional changes include:

* Treat android sdk as a Gradle artifact. This involves setting up an Ivy repo to match the custom layout of the Google SDK repository and a Gradle artifact transform that can extract android.jar from the SDK archive and seamlessly expose it as a dependency. This ensures SDKs are cached between `gradle clean`s and removes a whole bunch of custom download / unzip logic (at the expense of a bunch of Gradle artifact handling code).
* Rename some modules to better describe their purpose (maybe?).

.circleci/config.yml

@@ -17,8 +17,6 @@ jobs:
           key: v1-gradle-wrapper-{{ checksum "gradle/wrapper/gradle-wrapper.properties" }}
       - restore_cache:
           key: v1-gradle-cache-{{ checksum "build.gradle.kts" }}
-      - restore_cache:
-          key: v1-sdk-cache-{{ checksum "build.gradle.kts" }}
 
       - run:
           name: Build and test
@@ -32,10 +30,6 @@ jobs:
           paths:
             - ~/.gradle/caches
           key: v1-gradle-cache-{{ checksum "build.gradle.kts" }}
-      - save_cache:
-          paths:
-            - build/sdk-archives
-          key: v1-sdk-cache-{{ checksum "build.gradle.kts" }}
 
       - run:
           name: Save test results
@@ -49,6 +43,9 @@ jobs:
       - store_artifacts:
           path: ~/test-results/junit
 
+      - run:
+          name: Deploy locally
+          command: ./gradlew publishToMavenLocal
       - run:
           name: Deploy (if release)
           command: "if [[ \"$CIRCLE_BRANCH\" == master ]]; then ./gradlew publish closeAndReleaseRepository -Dorg.gradle.internal.http.socketTimeout=120000 -Dorg.gradle.internal.network.retry.max.attempts=1 -Dorg.gradle.internal.publish.checksums.insecure=true; else echo skipping publishing; fi"

api/19/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-4.4.2",
-    sdkFile = "android-19_r04.zip",
+    sdk = "android-19:r04",
     coreLibDesugaring = true
 )

api/20/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-4.4W.2",
-    sdkFile = "android-20_r02.zip",
+    sdk = "android-20:r02",
     coreLibDesugaring = true
 )

api/21/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-5.0.1",
-    sdkFile = "android-21_r02.zip",
+    sdk = "android-21:r02",
     coreLibDesugaring = true
 )

api/22/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-5.1.1",
-    sdkFile = "android-22_r02.zip",
+    sdk = "android-22:r02",
     coreLibDesugaring = true
 )

api/23/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-6.0",
-    sdkFile = "platform-23_r03.zip",
+    sdk = "platform-23:r03",
     coreLibDesugaring = true
 )

api/24/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-7.0",
-    sdkFile = "platform-24_r02.zip",
+    sdk = "platform-24:r02",
     coreLibDesugaring = true
 )

api/25/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-7.1.1",
-    sdkFile = "platform-25_r03.zip",
+    sdk = "platform-25:r03",
     coreLibDesugaring = true
 )

api/26/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-8.0.0",
-    sdkFile = "platform-26_r02.zip",
+    sdk = "platform-26:r02",
     coreLibDesugaring = true
 )

api/27/build.gradle.kts

@@ -15,7 +15,6 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-8.1.0",
-    sdkFile = "platform-27_r03.zip",
+    sdk = "platform-27:r03",
     coreLibDesugaring = true
 )

api/28/build.gradle.kts

@@ -15,6 +15,5 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-9",
-    sdkFile = "platform-28_r06.zip"
+    sdk = "platform-28:r06"
 )

api/29/build.gradle.kts

@@ -15,6 +15,5 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-10",
-    sdkFile = "platform-29_r04.zip"
+    sdk = "platform-29:r04"
 )

api/30/build.gradle.kts

@@ -15,6 +15,5 @@
 
 buildSignatures(
     apiLevel = name,
-    sdkDir = "android-11",
-    sdkFile = "platform-30_r03.zip"
+    sdk = "platform-30:r03"
 )

basic-sugar/README.md

@@ -0,0 +1,5 @@
+# Standard Desugared APIs
+
+Contains stubs for APIs desugared by vanilla D8 in AGP 3.x+ without core library desugaring.
+
+Currently must be compiled with java 8.

sugar/src/main/java/java/lang/Boolean.java → basic-sugar/src/main/java/java/lang/Boolean.java

@@ -1,6 +1,6 @@
 package java.lang;
 
-public abstract class Boolean implements java.io.Serializable, Comparable<Boolean> {
+public abstract class Boolean {
     public static int hashCode(boolean b) {
         throw new RuntimeException();
     }

sugar/src/main/java/java/lang/Byte.java → basic-sugar/src/main/java/java/lang/Byte.java

@@ -1,6 +1,6 @@
 package java.lang;
 
-public abstract class Byte extends Number implements Comparable<Byte> {
+public abstract class Byte {
     public static int hashCode(byte i) {
         throw new RuntimeException();
     }

sugar/src/main/java/java/lang/Character.java → basic-sugar/src/main/java/java/lang/Character.java

@@ -1,6 +1,6 @@
 package java.lang;
 
-public abstract class Character implements java.io.Serializable, Comparable<Character> {
+public abstract class Character {
     public static int compare(char a, char b) {
         throw new RuntimeException();
     }

sugar/src/main/java/java/lang/Double.java → basic-sugar/src/main/java/java/lang/Double.java

@@ -1,6 +1,6 @@
 package java.lang;
 
-public abstract class Double extends Number implements Comparable<Double> {
+public abstract class Double {
     public static boolean isFinite(double d) {
         throw new RuntimeException();
     }

sugar/src/main/java/java/lang/Float.java → basic-sugar/src/main/java/java/lang/Float.java

@@ -1,6 +1,6 @@
 package java.lang;
 
-public abstract class Float extends Number implements Comparable<Float> {
+public abstract class Float {
     public static int hashCode(float d) {
         throw new RuntimeException();
     }

sugar/src/main/java/java/lang/Integer.java → basic-sugar/src/main/java/java/lang/Integer.java

@@ -1,6 +1,6 @@
 package java.lang;
 
-public abstract class Integer extends Number implements Comparable<Integer> {
+public abstract class Integer {
     public static int hashCode(int value) {
         throw new RuntimeException();
     }

sugar/src/main/java/java/lang/Long.java → basic-sugar/src/main/java/java/lang/Long.java

@@ -1,6 +1,6 @@
 package java.lang;
 
-public abstract class Long extends Number implements Comparable<Long> {
+public abstract class Long {
     public static int hashCode(long value) {
         throw new RuntimeException();
     }

sugar/src/main/java/java/lang/Short.java → basic-sugar/src/main/java/java/lang/Short.java

@@ -1,6 +1,6 @@
 package java.lang;
 
-public abstract class Short extends Number implements Comparable<Short> {
+public abstract class Short {
     public static int hashCode(short i) {
         throw new RuntimeException();
     }

build.gradle.kts

@@ -32,6 +32,8 @@ allprojects {
     repositories {
         google()
         jcenter()
+
+        androidSdk()
     }
 }
 

buildSrc/build.gradle.kts

@@ -23,7 +23,5 @@ plugins {
 }
 
 dependencies {
-    implementation("de.undercouch:gradle-download-task:4.0.2")
-    implementation("ru.vyarus:gradle-animalsniffer-plugin:1.5.0")
     implementation("io.codearte.gradle.nexus:gradle-nexus-staging-plugin:0.21.2")
 }

buildSrc/src/main/kotlin/Scopes.kt

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2020. Toast Inc.
+ *
+ * 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.
+ */
+
+object Scopes {
+    const val generator = "generator"
+    const val sdk = "sdk"
+    const val standardSugar = "sugar"
+    const val exerciseStandardSugar = "exerciseStandardSugar"
+    const val coreLibSugar = "coreLibSugar"
+}

buildSrc/src/main/kotlin/androidSdk.kt

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2020. Toast Inc.
+ *
+ * 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.
+ */
+
+import org.gradle.api.Project
+import org.gradle.api.artifacts.dsl.RepositoryHandler
+import org.gradle.api.artifacts.transform.InputArtifact
+import org.gradle.api.artifacts.transform.TransformAction
+import org.gradle.api.artifacts.transform.TransformOutputs
+import org.gradle.api.artifacts.transform.TransformParameters
+import org.gradle.api.attributes.Attribute
+import org.gradle.api.file.FileSystemLocation
+import org.gradle.api.provider.Provider
+import org.gradle.kotlin.dsl.dependencies
+import org.gradle.kotlin.dsl.registerTransform
+import java.util.zip.ZipFile
+
+const val SDK_GROUP = "com.google.android.sdk"
+
+private const val ANDROID_JAR = "android.jar"
+private val ARTIFACT_TYPE_ATTRIBUTE = Attribute.of("artifactType", String::class.java)
+private val UNPACKED_SDK_ATTRIBUTE = Attribute.of("unpackedSdk", Boolean::class.javaObjectType)
+
+/**
+ * This [artifact transform](https://docs.gradle.org/current/userguide/artifact_transforms.html)
+ * extracts android.jar from the Android SDK Platform zip archive.
+ */
+abstract class ExtractSdkTransform : TransformAction<TransformParameters.None> {
+    @get:InputArtifact
+    abstract val inputArtifact: Provider<FileSystemLocation>
+
+    override fun transform(outputs: TransformOutputs) {
+        val sdkArchive = ZipFile(inputArtifact.get().asFile)
+
+        val androidJarEntry = sdkArchive.entries().asSequence().find { it.name.endsWith(ANDROID_JAR) }
+
+        sdkArchive.getInputStream(androidJarEntry).use { i ->
+            outputs.file(ANDROID_JAR).outputStream().use { o ->
+                i.copyTo(o)
+            }
+        }
+    }
+}
+
+fun Project.extractSdk() {
+    configurations.named("sdk") {
+        attributes.attribute(UNPACKED_SDK_ATTRIBUTE, true)
+    }
+
+    dependencies {
+        attributesSchema {
+            attribute(UNPACKED_SDK_ATTRIBUTE)
+        }
+
+        artifactTypes.create("zip") {
+            attributes.attribute(UNPACKED_SDK_ATTRIBUTE, false)
+        }
+
+        registerTransform(ExtractSdkTransform::class) {
+            from.attribute(UNPACKED_SDK_ATTRIBUTE, false).attribute(ARTIFACT_TYPE_ATTRIBUTE, "zip")
+            to.attribute(UNPACKED_SDK_ATTRIBUTE, true).attribute(ARTIFACT_TYPE_ATTRIBUTE, "jar")
+        }
+    }
+}
+
+
+/**
+ * Enables Gradle to download artifacts from the Android SDK (non-Maven) repository.
+ */
+fun RepositoryHandler.androidSdk() {
+    ivy {
+        setUrl("https://dl.google.com/android/repository")
+
+        content {
+            includeGroup(SDK_GROUP)
+        }
+
+        patternLayout {
+            artifact("/[module]_[revision].[ext]")
+        }
+
+        metadataSources {
+            artifact()
+        }
+    }
+}

buildSrc/src/main/kotlin/dependencies.kt

@@ -14,16 +14,20 @@
  */
 
 object versions {
+    const val animalSniffer = "1.16"
+    const val clikt = "3.0.1"
     const val desugarJdkLibs = "1.0.10"
     const val r8 = "1.5.68"
-    const val kotlin = "1.3.60"
+    const val kotlin = "1.4.10"
     const val javapoet = "1.11.1"
     const val javassist = "3.26.0-GA"
     const val junit = "4.12"
     const val truth = "1.0"
 }
 
 object libraries {
+    val animalSniffer = "org.codehaus.mojo:animal-sniffer:${versions.animalSniffer}"
+    val clikt = "com.github.ajalt.clikt:clikt:${versions.clikt}"
     val desugarJdkLibs = "com.android.tools:desugar_jdk_libs:${versions.desugarJdkLibs}"
     val r8 = "com.android.tools:r8:${versions.r8}"
     val javapoet = "com.squareup:javapoet:${versions.javapoet}"