Revert "[flutter_tools] remove alternative build aot code path (#49577)" (#49641)

This reverts commit d1e25bf233e9d19a7f5fece0cf9c1fd263c0c0e4.

dev/bots/test.dart

@@ -328,17 +328,8 @@ Future<void> _runBuildTests() async {
 
 Future<void> _flutterBuildAot(String relativePathToApplication) async {
   print('${green}Testing AOT build$reset for $cyan$relativePathToApplication$reset...');
-  final String absoluteTarget = path.join(path.absolute(relativePathToApplication), 'lib', 'main.dart');
   await runCommand(flutter,
-    <String>[
+    <String>['build', 'aot', '-v'],
-      'assemble',
-      '-dTargetFile=$absoluteTarget',
-      '-dTargetPlatform=android',
-      '-dBuildMode=release',
-      '--output=build/aot',
-      'android_aot_bundle_release_android-arm64',
-      'android_aot_bundle_release_android-arm',
-    ],
     workingDirectory: path.join(flutterRoot, relativePathToApplication),
   );
 }

packages/flutter_tools/lib/src/aot.dart

@@ -6,13 +6,17 @@ import 'dart:async';
 
 import 'package:meta/meta.dart';
 
+import 'base/build.dart';
 import 'base/common.dart';
+import 'base/io.dart';
 import 'base/logger.dart';
+import 'base/process.dart';
 import 'build_info.dart';
 import 'build_system/build_system.dart';
 import 'build_system/targets/dart.dart';
 import 'build_system/targets/ios.dart';
 import 'cache.dart';
+import 'dart/package_map.dart';
 import 'globals.dart' as globals;
 import 'ios/bitcode.dart';
 import 'project.dart';
@@ -51,7 +55,123 @@ class AotBuilder {
       );
       return;
     }
-    throwToolExit('"flutter build aot" does not support configuration: $platform/$buildMode.');
+
+    if (bitcode) {
+      if (platform != TargetPlatform.ios) {
+        throwToolExit('Bitcode is only supported on iOS (TargetPlatform is $platform).');
+      }
+      await validateBitcode(buildMode, platform);
+    }
+
+    Status status;
+    if (!quiet) {
+      final String typeName = globals.artifacts.getEngineType(platform, buildMode);
+      status = globals.logger.startProgress(
+        'Building AOT snapshot in ${getFriendlyModeName(buildMode)} mode ($typeName)...',
+        timeout: timeoutConfiguration.slowOperation,
+      );
+    }
+    try {
+      final AOTSnapshotter snapshotter = AOTSnapshotter(reportTimings: reportTimings);
+
+      // Compile to kernel.
+      final String kernelOut = await snapshotter.compileKernel(
+        platform: platform,
+        buildMode: buildMode,
+        mainPath: mainDartFile,
+        packagesPath: PackageMap.globalPackagesPath,
+        trackWidgetCreation: false,
+        outputPath: outputPath,
+        extraFrontEndOptions: extraFrontEndOptions,
+        dartDefines: dartDefines,
+      );
+      if (kernelOut == null) {
+        throwToolExit('Compiler terminated unexpectedly.');
+        return;
+      }
+
+      // Build AOT snapshot.
+      if (platform == TargetPlatform.ios) {
+        // Determine which iOS architectures to build for.
+        final Map<DarwinArch, String> iosBuilds = <DarwinArch, String>{};
+        for (final DarwinArch arch in iosBuildArchs) {
+          iosBuilds[arch] = globals.fs.path.join(outputPath, getNameForDarwinArch(arch));
+        }
+
+        // Generate AOT snapshot and compile to arch-specific App.framework.
+        final Map<DarwinArch, Future<int>> exitCodes = <DarwinArch, Future<int>>{};
+        iosBuilds.forEach((DarwinArch iosArch, String outputPath) {
+          exitCodes[iosArch] = snapshotter.build(
+            platform: platform,
+            darwinArch: iosArch,
+            buildMode: buildMode,
+            mainPath: kernelOut,
+            packagesPath: PackageMap.globalPackagesPath,
+            outputPath: outputPath,
+            extraGenSnapshotOptions: extraGenSnapshotOptions,
+            bitcode: bitcode,
+            quiet: quiet,
+          ).then<int>((int buildExitCode) {
+            return buildExitCode;
+          });
+        });
+
+        // Merge arch-specific App.frameworks into a multi-arch App.framework.
+        if ((await Future.wait<int>(exitCodes.values)).every((int buildExitCode) => buildExitCode == 0)) {
+          final Iterable<String> dylibs = iosBuilds.values.map<String>(
+              (String outputDir) => globals.fs.path.join(outputDir, 'App.framework', 'App'));
+          globals.fs.directory(globals.fs.path.join(outputPath, 'App.framework'))..createSync();
+          await processUtils.run(
+            <String>[
+              'lipo',
+              ...dylibs,
+              '-create',
+              '-output', globals.fs.path.join(outputPath, 'App.framework', 'App'),
+            ],
+            throwOnError: true,
+          );
+        } else {
+          status?.cancel();
+          exitCodes.forEach((DarwinArch iosArch, Future<int> exitCodeFuture) async {
+            final int buildExitCode = await exitCodeFuture;
+            globals.printError('Snapshotting ($iosArch) exited with non-zero exit code: $buildExitCode');
+          });
+        }
+      } else {
+        // Android AOT snapshot.
+        final int snapshotExitCode = await snapshotter.build(
+          platform: platform,
+          buildMode: buildMode,
+          mainPath: kernelOut,
+          packagesPath: PackageMap.globalPackagesPath,
+          outputPath: outputPath,
+          extraGenSnapshotOptions: extraGenSnapshotOptions,
+          bitcode: false,
+        );
+        if (snapshotExitCode != 0) {
+          status?.cancel();
+          throwToolExit('Snapshotting exited with non-zero exit code: $snapshotExitCode');
+        }
+      }
+    } on ProcessException catch (error) {
+      // Catch the String exceptions thrown from the `runSync` methods below.
+      status?.cancel();
+      globals.printError(error.toString());
+      return;
+    }
+    status?.stop();
+
+    if (outputPath == null) {
+      throwToolExit(null);
+    }
+
+    final String builtMessage = 'Built to $outputPath${globals.fs.path.separator}.';
+    if (quiet) {
+      globals.printTrace(builtMessage);
+    } else {
+      globals.printStatus(builtMessage);
+    }
+    return;
   }
 
   bool _canUseAssemble(TargetPlatform targetPlatform) {