[flutter_tools] flutter precache downloads all enabled platforms if no flags are provided (#73733)

packages/flutter_tools/lib/src/commands/precache.dart

diff --git a/packages/flutter_tools/lib/src/commands/precache.dart b/packages/flutter_tools/lib/src/commands/precache.dart
index 6854fb8..58b151b 100644
--- a/packages/flutter_tools/lib/src/commands/precache.dart
+++ b/packages/flutter_tools/lib/src/commands/precache.dart
@@ -28,19 +28,19 @@
         help: 'Precache artifacts for all host platforms.');
     argParser.addFlag('force', abbr: 'f', negatable: false,
         help: 'Force re-downloading of artifacts.');
-    argParser.addFlag('android', negatable: true, defaultsTo: true,
+    argParser.addFlag('android', negatable: true, defaultsTo: false,
         help: 'Precache artifacts for Android development.',
         hide: verboseHelp);
-    argParser.addFlag('android_gen_snapshot', negatable: true, defaultsTo: true,
+    argParser.addFlag('android_gen_snapshot', negatable: true, defaultsTo: false,
         help: 'Precache gen_snapshot for Android development.',
         hide: !verboseHelp);
-    argParser.addFlag('android_maven', negatable: true, defaultsTo: true,
+    argParser.addFlag('android_maven', negatable: true, defaultsTo: false,
         help: 'Precache Gradle dependencies for Android development.',
         hide: !verboseHelp);
     argParser.addFlag('android_internal_build', negatable: true, defaultsTo: false,
         help: 'Precache dependencies for internal Android development.',
         hide: !verboseHelp);
-    argParser.addFlag('ios', negatable: true, defaultsTo: true,
+    argParser.addFlag('ios', negatable: true, defaultsTo: false,
         help: 'Precache artifacts for iOS development.');
     argParser.addFlag('web', negatable: true, defaultsTo: false,
         help: 'Precache artifacts for web development.');
@@ -69,7 +69,9 @@
   final String name = 'precache';
 
   @override
-  final String description = "Populate the Flutter tool's cache of binary artifacts.";
+  final String description = "Populate the Flutter tool's cache of binary artifacts.\n\n"
+    'If no explicit platform flags are provided, this command will download the artifacts '
+    'for all currently enabled platforms';
 
   @override
   bool get shouldUpdateCache => false;
@@ -143,7 +145,12 @@
     if (boolArg('use-unsigned-mac-binaries')) {
       _cache.useUnsignedMacBinaries = true;
     }
-    _cache.platformOverrideArtifacts = _explicitArtifactSelections();
+    final Set<String> explicitlyEnabled = _explicitArtifactSelections();
+    _cache.platformOverrideArtifacts = explicitlyEnabled;
+
+    // If the user did not provide any artifact flags, then download
+    // all artifacts that correspond to an enabled platform.
+    final bool downloadDefaultArtifacts = explicitlyEnabled.isEmpty;
     final Map<String, String> umbrellaForArtifact = _umbrellaForArtifactMap();
     final Set<DevelopmentArtifact> requiredArtifacts = <DevelopmentArtifact>{};
     for (final DevelopmentArtifact artifact in DevelopmentArtifact.values) {
@@ -152,7 +159,7 @@
       }
 
       final String argumentName = umbrellaForArtifact[artifact.name] ?? artifact.name;
-      if (includeAllPlatforms || boolArg(argumentName)) {
+      if (includeAllPlatforms || boolArg(argumentName) || downloadDefaultArtifacts) {
         requiredArtifacts.add(artifact);
       }
     }

packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart

diff --git a/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart b/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
index 2a23db2..c5396e7 100644
--- a/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
+++ b/packages/flutter_tools/test/commands.shard/hermetic/precache_test.dart
@@ -268,6 +268,7 @@
       const <String>[
         'precache',
         '--no-ios',
+        '--android',
         '--android_gen_snapshot',
         '--android_maven',
         '--android_internal_build',
@@ -403,6 +404,34 @@
 
     verify(cache.clearStampFiles()).called(1);
   });
+
+  testUsingContext('precache downloads all enabled platforms if no flags are provided.', () async {
+    final PrecacheCommand command = PrecacheCommand(
+      cache: cache,
+      logger: BufferLogger.test(),
+      featureFlags: TestFeatureFlags(
+        isWebEnabled: true,
+        isLinuxEnabled: true,
+        isWindowsEnabled: true,
+        isMacOSEnabled: true,
+        isIOSEnabled: false,
+        isAndroidEnabled: false,
+      ),
+      platform: FakePlatform(environment: <String, String>{}),
+    );
+    await createTestCommandRunner(command).run(const <String>['precache']);
+
+    expect(
+      artifacts,
+      unorderedEquals(<DevelopmentArtifact>{
+        DevelopmentArtifact.web,
+        DevelopmentArtifact.macOS,
+        DevelopmentArtifact.windows,
+        DevelopmentArtifact.linux,
+        DevelopmentArtifact.universal,
+        // iOS and android specifically excluded
+      }));
+  });
 }
 
 class MockCache extends Mock implements Cache {}