Add build warning for non-debug desktop builds (#38932)

When building in profile or release mode on desktop, add a prominent
warning that it's actually a debug build. This is to help address issues
with people being unaware of the current state of builds due to
following third-party guides rather than official documentation.

macOS is not included since PRs are in flight for macOS release support.

packages/flutter_tools/lib/src/linux/build_linux.dart

@@ -38,6 +38,15 @@ export PROJECT_DIR=${linuxProject.project.directory.path}
     ..createSync(recursive: true)
     ..writeAsStringSync(buffer.toString());
 
+  if (!buildInfo.isDebug) {
+    const String warning = '🚧 ';
+    printStatus(warning * 20);
+    printStatus('Warning: Only debug is currently implemented for Linux. This is effectively a debug build.');
+    printStatus('See https://github.com/flutter/flutter/issues/38478 for details and updates.');
+    printStatus(warning * 20);
+    printStatus('');
+  }
+
   // Invoke make.
   final Stopwatch sw = Stopwatch()..start();
   final Process process = await processManager.start(<String>[

packages/flutter_tools/lib/src/windows/build_windows.dart

@@ -42,6 +42,15 @@ Future<void> buildWindows(WindowsProject windowsProject, BuildInfo buildInfo, {S
         'Please run `flutter doctor` for more details.');
   }
 
+  if (!buildInfo.isDebug) {
+    const String warning = '🚧 ';
+    printStatus(warning * 20);
+    printStatus('Warning: Only debug is currently implemented for Windows. This is effectively a debug build.');
+    printStatus('See https://github.com/flutter/flutter/issues/38477 for details and updates.');
+    printStatus(warning * 20);
+    printStatus('');
+  }
+
   final String buildScript = fs.path.join(
     Cache.flutterRoot,
     'packages',

packages/flutter_tools/test/general.shard/commands/build_linux_test.dart

@@ -7,10 +7,12 @@ import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
+import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/platform.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/build.dart';
 import 'package:flutter_tools/src/features.dart';
+import 'package:flutter_tools/src/globals.dart';
 import 'package:flutter_tools/src/linux/makefile.dart';
 import 'package:flutter_tools/src/project.dart';
 import 'package:mockito/mockito.dart';
@@ -131,6 +133,35 @@ BINARY_NAME=fizz_bar
   }, overrides: <Type, Generator>{
     FeatureFlags: () => TestFeatureFlags(isLinuxEnabled: false),
   });
+
+  testUsingContext('Release build prints an under-construction warning', () async {
+    final BuildCommand command = BuildCommand();
+    applyMocksToCommand(command);
+    fs.file('linux/build.sh').createSync(recursive: true);
+    fs.file('pubspec.yaml').createSync();
+    fs.file('.packages').createSync();
+    fs.file(fs.path.join('lib', 'main.dart')).createSync(recursive: true);
+
+    when(mockProcessManager.start(<String>[
+      'make',
+      '-C',
+      '/linux',
+    ], runInShell: true)).thenAnswer((Invocation invocation) async {
+      return mockProcess;
+    });
+
+    await createTestCommandRunner(command).run(
+      const <String>['build', 'linux']
+    );
+
+    final BufferLogger bufferLogger = logger;
+    expect(bufferLogger.statusText, contains('🚧'));
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem(),
+    ProcessManager: () => mockProcessManager,
+    Platform: () => linuxPlatform,
+    FeatureFlags: () => TestFeatureFlags(isLinuxEnabled: true),
+  });
 }
 
 class MockProcessManager extends Mock implements ProcessManager {}

packages/flutter_tools/test/general.shard/commands/build_windows_test.dart

@@ -6,10 +6,12 @@ import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/common.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
+import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/platform.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/build.dart';
 import 'package:flutter_tools/src/features.dart';
+import 'package:flutter_tools/src/globals.dart';
 import 'package:flutter_tools/src/windows/visual_studio.dart';
 import 'package:mockito/mockito.dart';
 import 'package:process/process.dart';
@@ -139,6 +141,38 @@ void main() {
     VisualStudio: () => mockVisualStudio,
     FeatureFlags: () => TestFeatureFlags(isWindowsEnabled: true),
   });
+
+  testUsingContext('Release build prints an under-construction warning', () async {
+    final BuildCommand command = BuildCommand();
+    applyMocksToCommand(command);
+    fs.file(solutionPath).createSync(recursive: true);
+    when(mockVisualStudio.vcvarsPath).thenReturn(vcvarsPath);
+    fs.file('pubspec.yaml').createSync();
+    fs.file('.packages').createSync();
+    fs.file(fs.path.join('lib', 'main.dart')).createSync(recursive: true);
+
+    when(mockProcessManager.start(<String>[
+      r'C:\packages\flutter_tools\bin\vs_build.bat',
+      vcvarsPath,
+      fs.path.basename(solutionPath),
+      'Release',
+    ], workingDirectory: fs.path.dirname(solutionPath))).thenAnswer((Invocation invocation) async {
+      return mockProcess;
+    });
+
+    await createTestCommandRunner(command).run(
+      const <String>['build', 'windows']
+    );
+
+    final BufferLogger bufferLogger = logger;
+    expect(bufferLogger.statusText, contains('🚧'));
+  }, overrides: <Type, Generator>{
+    FileSystem: () => memoryFilesystem,
+    ProcessManager: () => mockProcessManager,
+    Platform: () => windowsPlatform,
+    VisualStudio: () => mockVisualStudio,
+    FeatureFlags: () => TestFeatureFlags(isWindowsEnabled: true),
+  });
 }
 
 class MockProcessManager extends Mock implements ProcessManager {}