Android: Standardize the use of application id and namespace (#5210)

This PR standardises the use of application id and namespace. It is also
one of the pre-requisites of making hilt instrumented tests to work.

The application id is a unique id for every android app , so the android
manifest package depends on it.

The android manifest package is also used whenever there's a relative
path for Applications and activities so

```xml
<manifest package="com.foo">
    <application android:name=".TodoApplication"/>
</manifest>
```

Becomes 

```xml
<manifest package="com.foo">
    <application android:name="com.foo.TodoApplication"/>
</manifest>
```

During manifest merging. Because this happens when the manifest is
loaded (before everything is merged) we start with the manifest package
being the android namespace. We then pass the package property to the
merger to be the application id (the package for each up is unique).
This is what appears to be happening in AGP as well. (It is also the
reason why I was confused when reverse engineering the AGP behaviour and
was alternating between namespace and application id)


I've also cleaned up some of the xml manual modifications that are not
needed anymore as are handled by the merger tool

Author: vaslabs

example/thirdparty/androidtodo/build.mill

@@ -26,7 +26,7 @@ object app extends AndroidAppKotlinModule with AndroidBuildConfig with AndroidHi
 
   def androidApplicationNamespace = "com.example.android.architecture.blueprints.todoapp"
   // TODO change this to com.example.android.architecture.blueprints.main when mill supports build variants
-  def androidApplicationId = "com.example.android.architecture.blueprints.todoapp"
+  def androidApplicationId = "com.example.android.architecture.blueprints.main"
 
   def androidSdkModule = mill.define.ModuleRef(androidSdkModule0)
 
@@ -177,10 +177,10 @@ object `shared-test` extends AndroidKotlinModule with AndroidHiltSupport {
 
 > ./mill show app.androidRun --activity com.example.android.architecture.blueprints.todoapp.TodoActivity
 [
-  "Starting: Intent { cmp=com.example.android.architecture.blueprints.todoapp/.TodoActivity }",
+  "Starting: Intent { cmp=com.example.android.architecture.blueprints.main/com.example.android.architecture.blueprints.todoapp.TodoActivity }",
   "Status: ok",
   "LaunchState: COLD",
-  "Activity: com.example.android.architecture.blueprints.todoapp/.TodoActivity",
+  "Activity: com.example.android.architecture.blueprints.main/com.example.android.architecture.blueprints.todoapp.TodoActivity",
   "TotalTime: ...",
   "WaitTime: ...",
   "Complete"

libs/androidlib/src/mill/androidlib/AndroidAppModule.scala

@@ -60,10 +60,10 @@ trait AndroidAppModule extends AndroidModule { outer =>
   protected val debugKeyPass = "mill-android"
 
   /**
-   * The namespace of the android application which is used
-   * to specify the fully qualified classpath of the activity.
+   *   Every Android module has a namespace,
+   *   which is used as the Kotlin or Java package name for its generated R and BuildConfig classes.
    *
-   * For instance, it is used as the package name in Android Manifest
+   * See more in [[https://developer.android.com/build/configure-app-module#set-namespace]]
    */
   def androidApplicationNamespace: String
 
@@ -74,10 +74,8 @@ trait AndroidAppModule extends AndroidModule { outer =>
   override final def androidNamespace: String = androidApplicationNamespace
 
   /**
-   * Android Application Id which is typically package.main .
-   * Can be used for build variants.
-   *
-   * Build variant feature is not yet implemented!
+   * Android Application Id unique to every android application.
+   * See more in [[https://developer.android.com/build/configure-app-module#set-application-id]]
    */
   def androidApplicationId: String
 
@@ -92,19 +90,15 @@ trait AndroidAppModule extends AndroidModule { outer =>
    * TODO dynamically add android:debuggable
    */
   override def androidManifest: T[PathRef] = Task {
-    val manifestFromSourcePath = moduleDir / "src/main/AndroidManifest.xml"
+    val manifestFromSourcePath = androidManifestLocation().path
 
     val manifestElem = XML.loadFile(manifestFromSourcePath.toString())
     // add the application package
     val manifestWithPackage =
-      manifestElem % Attribute(None, "package", Text(androidApplicationNamespace), Null)
-
-    val manifestWithUsesSdk = manifestWithPackage.copy(
-      child = androidManifestUsesSdkSection() ++ manifestWithPackage.child
-    )
+      manifestElem % Attribute(None, "package", Text(androidNamespace), Null)
 
     val generatedManifestPath = Task.dest / "AndroidManifest.xml"
-    os.write(generatedManifestPath, manifestWithUsesSdk.mkString)
+    os.write(generatedManifestPath, manifestWithPackage.mkString)
 
     PathRef(generatedManifestPath)
   }
@@ -294,6 +288,10 @@ trait AndroidAppModule extends AndroidModule { outer =>
         s"version_code=${androidVersionCode()}",
         "--property",
         s"version_name=${androidVersionName()}",
+        "--property",
+        s"package=${androidApplicationId}",
+        "--manifest-placeholders",
+        s"applicationId=${androidApplicationId}",
         "--out",
         mergedManifestPath.toString()
       ) ++ libManifests.flatMap(m => Seq("--libs", m.path.toString())),
@@ -671,7 +669,7 @@ trait AndroidAppModule extends AndroidModule { outer =>
         "am",
         "start",
         "-n",
-        s"${androidApplicationNamespace}/${activity}",
+        s"${androidApplicationId}/${activity}",
         "-W"
       )
     ).out.lines()
@@ -683,7 +681,7 @@ trait AndroidAppModule extends AndroidModule { outer =>
    */
   def androidReleaseKeyPath: T[Seq[PathRef]] = {
     val subPaths = androidReleaseKeyName.map(os.sub / _).toSeq
-    Task.Sources(subPaths: _*)
+    Task.Sources(subPaths*)
   }
 
   /*
@@ -1057,7 +1055,7 @@ trait AndroidAppModule extends AndroidModule { outer =>
     override def androidSdkModule: ModuleRef[AndroidSdkModule] = outer.androidSdkModule
     override def androidManifest: T[PathRef] = outer.androidManifest()
 
-    override def androidApplicationId: String = outer.androidApplicationId
+    override def androidApplicationId: String = s"${outer.androidApplicationId}.test"
 
     override def androidApplicationNamespace: String = s"${outer.androidApplicationNamespace}.test"
 
@@ -1086,7 +1084,7 @@ trait AndroidAppModule extends AndroidModule { outer =>
 
     override def resolutionParams: Task[ResolutionParams] = Task.Anon(outer.resolutionParams())
 
-    override def androidApplicationId: String = s"${outer.androidApplicationId}"
+    override def androidApplicationId: String = s"${outer.androidApplicationId}.test"
     override def androidApplicationNamespace: String = s"${outer.androidApplicationNamespace}.test"
 
     override def androidReleaseKeyAlias: T[Option[String]] = outer.androidReleaseKeyAlias()
@@ -1105,7 +1103,7 @@ trait AndroidAppModule extends AndroidModule { outer =>
 
     private def androidInstrumentedTestsBaseManifest: Task[Elem] = Task.Anon {
       <manifest xmlns:android="http://schemas.android.com/apk/res/android" package={
-        androidApplicationNamespace
+        androidApplicationId
       }>
         {androidManifestUsesSdkSection()}
       </manifest>
@@ -1129,7 +1127,6 @@ trait AndroidAppModule extends AndroidModule { outer =>
       val destManifest = Task.dest / "AndroidManifest.xml"
       os.write(destManifest, manifestWithInstrumentation.toString)
       PathRef(destManifest)
-
     }
 
     override def androidVirtualDeviceIdentifier: String = outer.androidVirtualDeviceIdentifier

libs/androidlib/src/mill/androidlib/AndroidModule.scala

@@ -47,31 +47,23 @@ trait AndroidModule extends JavaModule {
    */
   def androidSdkModule: ModuleRef[AndroidSdkModule]
 
-  private def androidManifestUsesSdkSection: Task[Elem] = Task.Anon {
-    val minSdkVersion = androidMinSdk().toString
-    val targetSdkVersion = androidTargetSdk().toString
-    <uses-sdk android:minSdkVersion={minSdkVersion} />
-  }
+  def androidManifestLocation: T[PathRef] = Task.Source("src/main/AndroidManifest.xml")
 
   /**
    * Provides os.Path to an XML file containing configuration and metadata about your android application.
    * TODO dynamically add android:debuggable
    */
   def androidManifest: T[PathRef] = Task {
-    val manifestFromSourcePath = moduleDir / "src/main/AndroidManifest.xml"
+    val manifestFromSourcePath = androidManifestLocation().path
 
     val manifestElem = XML.loadFile(manifestFromSourcePath.toString()) %
       Attribute(None, "xmlns:android", Text("http://schemas.android.com/apk/res/android"), Null)
     // add the application package
     val manifestWithPackage =
       manifestElem % Attribute(None, "package", Text(androidNamespace), Null)
 
-    val manifestWithUsesSdk = manifestWithPackage.copy(
-      child = androidManifestUsesSdkSection() ++ manifestWithPackage.child
-    )
-
     val generatedManifestPath = Task.dest / "AndroidManifest.xml"
-    os.write(generatedManifestPath, manifestWithUsesSdk.mkString)
+    os.write(generatedManifestPath, manifestWithPackage.mkString)
 
     PathRef(generatedManifestPath)
   }

libs/androidlib/src/mill/androidlib/AndroidSdkModule.scala

@@ -40,7 +40,7 @@ trait AndroidSdkModule extends Module {
   /**
    * Specifies the version of the Manifest Merger.
    */
-  def manifestMergerVersion: T[String] = "31.7.3"
+  def manifestMergerVersion: T[String] = "31.10.0"
 
   /**
    * Specifies the version of the Android build tools to be used.