android: fix all linter warnings and treat warnings as errors (#521)

#Updates tailscale/corp#22284

Fixes and/or explicitly suppresses all linter warnings and
we will now fail the build if new warnings are introduced.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>

android/build.gradle

@@ -54,6 +54,10 @@ android {
         targetCompatibility JavaVersion.VERSION_17
     }
 
+    lintOptions {
+        warningsAsErrors true
+    }
+
     kotlinOptions {
         jvmTarget = "17"
     }

android/src/main/java/com/tailscale/ipn/AppSourceChecker.kt

@@ -15,10 +15,11 @@ object AppSourceChecker {
     val packageName = context.packageName
     Log.d(TAG, "Package name: $packageName")
 
-    val installerPackageName = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
+    val installerPackageName =
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
           packageManager.getInstallSourceInfo(packageName).installingPackageName
         } else {
-        packageManager.getInstallerPackageName(packageName)
+          @Suppress("deprecation") packageManager.getInstallerPackageName(packageName)
         }
 
     Log.d(TAG, "Installer package name: $installerPackageName")
@@ -30,5 +31,5 @@ object AppSourceChecker {
       null -> "unknown"
       else -> "unknown($installerPackageName)"
     }
-}
+  }
 }

android/src/main/java/com/tailscale/ipn/QuickToggleService.java

@@ -60,6 +60,7 @@ public class QuickToggleService extends TileService {
         }
     }
 
+    @SuppressWarnings("deprecation")
     @Override
     public void onClick() {
         boolean r;
@@ -77,6 +78,7 @@ public class QuickToggleService extends TileService {
                 // Request code for opening activity.
                 startActivityAndCollapse(PendingIntent.getActivity(this, 0, i, PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_IMMUTABLE));
             } else {
+                // Deprecated, but still required for older versions.
                 startActivityAndCollapse(i);
             }
         }

android/src/main/java/com/tailscale/ipn/ui/model/Permissions.kt

@@ -22,7 +22,7 @@ object Permissions {
     @Composable
     get() {
       val permissionStates = rememberMultiplePermissionsState(permissions = all.map { it.name })
-      return all.zip(permissionStates.permissions).filter { (permission, state) ->
+      return all.zip(permissionStates.permissions).filter { (_, state) ->
         !state.status.isGranted && !state.status.shouldShowRationale
       }
     }

android/src/main/java/com/tailscale/ipn/ui/theme/Theme.kt

@@ -44,7 +44,8 @@ fun AppTheme(useDarkTheme: Boolean = isSystemInDarkTheme(), content: @Composable
           // margins in list items.
           bodyMedium = MaterialTheme.typography.bodyMedium.copy(fontSize = 16.sp))
 
-  val systemUiController = rememberSystemUiController()
+  // TODO: Migrate to Activity.enableEdgeToEdge
+  @Suppress("deprecation") val systemUiController = rememberSystemUiController()
 
   DisposableEffect(systemUiController, useDarkTheme) {
     systemUiController.setStatusBarColor(color = colors.surfaceContainer)
@@ -446,7 +447,6 @@ val ColorScheme.disabled: Color
 val ColorScheme.searchBarColors: TextFieldColors
   @Composable
   get() {
-    val defaults = OutlinedTextFieldDefaults.colors()
     return OutlinedTextFieldDefaults.colors(
         focusedLeadingIconColor = MaterialTheme.colorScheme.onSurface,
         unfocusedLeadingIconColor = MaterialTheme.colorScheme.onSurface,

android/src/main/java/com/tailscale/ipn/ui/util/AndroidTVUtil.kt

@@ -15,7 +15,7 @@ import com.tailscale.ipn.ui.util.AndroidTVUtil.isAndroidTV
 object AndroidTVUtil {
   fun isAndroidTV(): Boolean {
     val pm = UninitializedApp.get().packageManager
-    return (pm.hasSystemFeature(PackageManager.FEATURE_TELEVISION) ||
+    return (pm.hasSystemFeature(@Suppress("deprecation") PackageManager.FEATURE_TELEVISION) ||
         pm.hasSystemFeature(PackageManager.FEATURE_LEANBACK))
   }
 }

android/src/main/java/com/tailscale/ipn/ui/view/ExitNodePicker.kt

@@ -61,7 +61,7 @@ fun ExitNodePicker(
           if (forcedExitNodeId != null) {
             Text(
                 text =
-                    managedByOrganization?.let {
+                    managedByOrganization.value?.let {
                       stringResource(R.string.exit_node_mdm_orgname, it)
                     } ?: stringResource(R.string.exit_node_mdm),
                 style = MaterialTheme.typography.bodyMedium,

android/src/main/java/com/tailscale/ipn/ui/view/MDMSettingsDebugView.kt

@@ -25,7 +25,10 @@ import com.tailscale.ipn.ui.viewModel.IpnViewModel
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun MDMSettingsDebugView(backToSettings: BackNavigation, model: IpnViewModel = viewModel()) {
+fun MDMSettingsDebugView(
+    backToSettings: BackNavigation,
+    @Suppress("UNUSED_PARAMETER") model: IpnViewModel = viewModel()
+) {
   Scaffold(topBar = { Header(R.string.current_mdm_settings, onBack = backToSettings) }) {
       innerPadding ->
     LazyColumn(modifier = Modifier.padding(innerPadding)) {

android/src/main/java/com/tailscale/ipn/ui/view/MainView.kt

@@ -251,7 +251,7 @@ fun MainView(
             }
           }
 
-      currentPingDevice?.let { peer ->
+      currentPingDevice?.let { _ ->
         ModalBottomSheet(onDismissRequest = { viewModel.onPingDismissal() }) {
           PingView(model = viewModel.pingViewModel)
         }

android/src/main/java/com/tailscale/ipn/ui/view/ManagedByView.kt

@@ -23,14 +23,16 @@ import com.tailscale.ipn.R
 import com.tailscale.ipn.mdm.MDMSettings
 import com.tailscale.ipn.ui.viewModel.IpnViewModel
 
+@Suppress("UNUSED_PARAMETER")
 @Composable
 fun ManagedByView(backToSettings: BackNavigation, model: IpnViewModel = viewModel()) {
-  Scaffold(topBar = { Header(R.string.managed_by, onBack = backToSettings) }) { innerPadding ->
+  Scaffold(topBar = { Header(R.string.managed_by, onBack = backToSettings) }) { _ ->
     Column(
         verticalArrangement =
             Arrangement.spacedBy(space = 20.dp, alignment = Alignment.CenterVertically),
         horizontalAlignment = Alignment.Start,
-        modifier = Modifier.fillMaxWidth().safeContentPadding().verticalScroll(rememberScrollState())) {
+        modifier =
+            Modifier.fillMaxWidth().safeContentPadding().verticalScroll(rememberScrollState())) {
           val managedByOrganization =
               MDMSettings.managedByOrganizationName.flow.collectAsState().value.value
           val managedByCaption = MDMSettings.managedByCaption.flow.collectAsState().value.value

android/src/main/java/com/tailscale/ipn/ui/viewModel/MainViewModel.kt

@@ -32,6 +32,7 @@ import kotlinx.coroutines.launch
 import java.time.Duration
 
 class MainViewModelFactory(private val vpnViewModel: VpnViewModel) : ViewModelProvider.Factory {
+  @Suppress("UNCHECKED_CAST")
   override fun <T : ViewModel> create(modelClass: Class<T>): T {
     if (modelClass.isAssignableFrom(MainViewModel::class.java)) {
       return MainViewModel(vpnViewModel) as T