Support namespace Android Gradle Plugin BaseExtension value.

This is in addition to supporting the `package` attribute in
AndroidManifest.xml.

In AGP 7 developers can use `namespace` instead of the manifest
attribute. In AGP 8 it will no longer be possible to use the `package`
attribute in AndroidManifest.xml.

^KT-50887 Fixed

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/AbstractKotlinAndroidGradleTests.kt

@@ -514,6 +514,17 @@ open class KotlinAndroid70GradleIT : KotlinAndroid36GradleIT() {
             assertCompiledKotlinSources(project.relativize(affectedSources))
         }
     }
+
+    @Test
+    fun testNamespaceDSLInsteadOfPackageAttributeInManifest() {
+        val project = Project("AndroidExtensionsProjectAGP7")
+        val options = defaultBuildOptions().copy(incremental = false)
+
+        project.build("assembleDebug", options = options) {
+            assertSuccessful()
+            assertContains("The 'kotlin-android-extensions' Gradle plugin is deprecated")
+        }
+    }
 }
 
 open class KotlinAndroid71GradleIT : KotlinAndroid70GradleIT() {

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/app/build.gradle

@@ -0,0 +1,25 @@
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+
+android {
+    compileSdkVersion 23
+    buildToolsVersion "25.0.2"
+    namespace "com.example.androidextensions"
+
+    defaultConfig {
+        applicationId "com.example.dagger.kotlin"
+        minSdkVersion 14
+        targetSdkVersion 23
+        versionCode 1
+        versionName "1.0"
+    }
+    sourceSets {
+        main.java.srcDirs += 'src/main/kotlin'
+    }
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/app/src/main/AndroidManifest.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <application android:label="app_name">
+        <activity
+            android:label="app_name"
+            android:name="com.example.androidextensions.MyActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+                <category android:name="android.intent.category.DEFAULT"/>
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/app/src/main/java/com/example/androidextensions/MyActivity.kt

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * 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.
+ */
+
+package com.example.androidextensions
+
+import android.os.Bundle
+import android.app.Activity
+import kotlinx.android.synthetic.main.activity_main.textView
+
+class HomeActivity : Activity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        myUtilFunction()
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_main)
+        
+        this.textView.setText("Hello, world!")
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/app/src/main/java/com/example/androidextensions/noLayoutUsages.kt

@@ -0,0 +1,3 @@
+package com.example.androidextensions
+
+fun myUtilFunction() = "OK"

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/app/src/main/res/layout/activity_main.xml

@@ -0,0 +1,9 @@
+<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <TextView android:id="@+id/textView"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content" />
+
+</RelativeLayout>

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/app/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">kotlin</string>
+</resources>

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/build.gradle

@@ -0,0 +1,24 @@
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+
+buildscript {
+    repositories {
+        mavenLocal()
+        maven { url 'https://maven.google.com' }
+        mavenCentral()
+        maven { url = uri("https://jcenter.bintray.com/") }
+    }
+
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+        classpath "com.android.tools.build:gradle:$android_tools_version"
+    }
+}
+
+allprojects {
+    repositories {
+        mavenLocal()
+        maven { url 'https://maven.google.com' }
+        mavenCentral()
+        maven { url = uri("https://jcenter.bintray.com/") }
+    }
+}

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/gradle.properties

@@ -0,0 +1 @@
+org.gradle.jvmargs=-XX:MaxPermSize=512m

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/AndroidExtensionsProjectAGP7/settings.gradle

@@ -0,0 +1 @@
+include ':app'

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/android/internal/AndroidSubplugin.kt

@@ -116,7 +116,7 @@ class AndroidSubplugin :
 
         val mainSourceSet = sourceSets.getByName("main")
         val manifestFile = mainSourceSet.manifest.srcFile
-        val applicationPackage = getApplicationPackageFromManifest(manifestFile) ?: run {
+        val applicationPackage = getApplicationPackage(androidExtension, manifestFile) ?: run {
             project.logger.warn(
                 "Application package name is not present in the manifest file (${manifestFile.absolutePath})"
             )
@@ -182,7 +182,7 @@ class AndroidSubplugin :
         )
 
         val mainSourceSet = androidExtension.sourceSets.getByName("main")
-        pluginOptions += SubpluginOption("package", getApplicationPackage(project, mainSourceSet))
+        pluginOptions += SubpluginOption("package", getApplicationPackage(androidExtension, project, mainSourceSet))
 
         fun addVariant(name: String, resDirectories: FileCollection) {
             val optionValue = lazy {
@@ -270,9 +270,9 @@ class AndroidSubplugin :
         return project.files(Callable { lazyFiles.value })
     }
 
-    private fun getApplicationPackage(project: Project, mainSourceSet: AndroidSourceSet): String {
+    private fun getApplicationPackage(androidExtension: BaseExtension, project: Project, mainSourceSet: AndroidSourceSet): String {
         val manifestFile = mainSourceSet.manifest.srcFile
-        val applicationPackage = getApplicationPackageFromManifest(manifestFile)
+        val applicationPackage = getApplicationPackage(androidExtension, manifestFile)
 
         if (applicationPackage == null) {
             project.logger.warn(
@@ -286,7 +286,34 @@ class AndroidSubplugin :
         }
     }
 
-    private fun getApplicationPackageFromManifest(manifestFile: File): String? {
+    private fun getApplicationPackage(androidExtension: BaseExtension, manifestFile: File): String? {
+        // Starting AGP 7 the package can be set via the DSL namespace value:
+        //
+        // android {
+        //   namespace "com.example"
+        // }
+        //
+        // instead of via the "package" attribute in the manifest file.
+        //
+        // Starting AGP 8, the package *must* be set via the DSL and the manifest file
+        // attribute cannot be used.
+        //
+        // See https://issuetracker.google.com/issues/172361895
+        //
+        // Therefore, we try to get the package from there first. Since we support AGP versions
+        // prior to AGP 7, we need to reflectively find and call it.
+        try {
+            val method = androidExtension.javaClass.getDeclaredMethod("getNamespace")
+            val result = method.invoke(androidExtension)
+            if (result is String && result.isNotEmpty()) {
+                return result
+            }
+        } catch (e: ReflectiveOperationException) {
+            // Ignore and try parsing manifest.
+        }
+
+        // Didn't find the namespace getter, or it was not set. Try parsing the
+        // manifest to find the "package" attribute from there.
         try {
             return manifestFile.parseXml().documentElement.getAttribute("package")
         } catch (e: Exception) {