Reapply "Tweak public APIs and use them in patch_sdk, dart2js, and kernel-service.""

pkg/front_end/lib/src/base/processed_options.dart

Index: pkg/front_end/lib/src/base/processed_options.dart
diff --git a/pkg/front_end/lib/src/base/processed_options.dart b/pkg/front_end/lib/src/base/processed_options.dart
index a42d2b54caa8c554bb705ee450a79a3a61a8ab64..b2e93ab6008cb4553aec0ad17fb6d3d515a3733e 100644
--- a/pkg/front_end/lib/src/base/processed_options.dart
+++ b/pkg/front_end/lib/src/base/processed_options.dart
@@ -4,17 +4,27 @@
 
 import 'dart:async';
 
+import 'package:front_end/compilation_error.dart';
 import 'package:front_end/compiler_options.dart';
 import 'package:front_end/file_system.dart';
-import 'package:front_end/src/fasta/translate_uri.dart';
 import 'package:front_end/src/base/performace_logger.dart';
+import 'package:front_end/src/fasta/ticker.dart';
+import 'package:front_end/src/fasta/translate_uri.dart';
 import 'package:front_end/src/incremental/byte_store.dart';
-import 'package:front_end/src/simple_error.dart';
+import 'package:kernel/kernel.dart'
+    show Program, loadProgramFromBytes, CanonicalName;
+import 'package:kernel/target/targets.dart';
+import 'package:kernel/target/vm_fasta.dart';
 import 'package:package_config/packages_file.dart' as package_config;
-import 'package:kernel/kernel.dart' show Program, loadProgramFromBytes;
+import 'package:source_span/source_span.dart' show SourceSpan;
 
-/// Wrapper around [CompilerOptions] which exposes the options in a form useful
-/// to the front end implementation.
+/// All options needed for the front end implementation.
+///
+/// This includes: all of [CompilerOptions] in a form useful to the
+/// implementation, default values for options that were not provided,
+/// and information derived from how the compiler was invoked (like the
+/// entry-points given to the compiler and whether a modular or whole-program
+/// API was used).
 ///
 /// The intent is that the front end should immediately wrap any incoming
 /// [CompilerOptions] object in this class before doing further processing, and
@@ -34,19 +44,58 @@ class ProcessedOptions {
   TranslateUri _uriTranslator;
 
   /// The SDK summary, or `null` if it has not been read yet.
+  ///
+  /// A summary, also referred to as "outline" internally, is a [Program] where
+  /// all method bodies are left out. In essence, it contains just API
+  /// signatures and constants. When strong-mode is enabled, the summary already
+  /// includes inferred types.
   Program _sdkSummaryProgram;
 
   /// The summary for each uri in `options.inputSummaries`.
+  ///
+  /// A summary, also referred to as "outline" internally, is a [Program] where
+  /// all method bodies are left out. In essence, it contains just API
+  /// signatures and constants. When strong-mode is enabled, the summary already
+  /// includes inferred types.
   List<Program> _inputSummariesPrograms;
 
+  /// Other programs that are meant to be linked and compiled with the input
+  /// sources.
+  List<Program> _linkedDependencies;
+
   /// The location of the SDK, or `null` if the location hasn't been determined
   /// yet.
   Uri _sdkRoot;
-
   Uri get sdkRoot => _sdkRoot ??= _normalizeSdkRoot();
 
+  Uri _sdkSummary;
+  Uri get sdkSummary => _sdkSummary ??= _computeSdkSummaryUri();
+
+  Ticker ticker;
+
+  bool get verbose => _raw.verbose;
+
+  bool get verify => _raw.verify;
+
+  bool get debugDump => _raw.debugDump;
+
+  /// Like [CompilerOptions.chaseDependencies] but with the appropriate default
+  /// value filled in.
+  bool get chaseDependencies => _raw.chaseDependencies ?? !_modularApi;
+
+  /// Whether the compiler was invoked with a modular API.
+  ///
+  /// Used to determine the default behavior for [chaseDependencies].
+  final bool _modularApi;
+
+  /// The entry-points provided to the compiler.
+  final List<Uri> inputs;
+
   /// Initializes a [ProcessedOptions] object wrapping the given [rawOptions].
-  ProcessedOptions(CompilerOptions rawOptions) : this._raw = rawOptions;
+  ProcessedOptions(CompilerOptions rawOptions,
+      [this._modularApi = false, this.inputs = const []])
+      : this._raw = rawOptions,
+        ticker = new Ticker(isVerbose: rawOptions.verbose);
 
   /// The logger to report compilation progress.
   PerformanceLog get logger {
@@ -58,28 +107,40 @@ class ProcessedOptions {
     return _raw.byteStore;
   }
 
+  // TODO(sigmund): delete. We should use messages with error codes directly
+  // instead.
+  void reportError(String message) {
+    _raw.onError(new _CompilationError(message));
+  }
+
   /// Runs various validations checks on the input options. For instance,
   /// if an option is a path to a file, it checks that the file exists.
   Future<bool> validateOptions() async {
-    var fs = _raw.fileSystem;
-    var root = _raw.sdkRoot;
+    for (var source in inputs) {
+      if (source.scheme == 'file' &&
+          !await fileSystem.entityForUri(source).exists()) {
+        reportError("Entry-point file not found: $source");
+        return false;
+      }
+    }
 
-    bool _report(String msg) {
-      _raw.onError(new SimpleError(msg));
+    if (_raw.sdkRoot != null &&
+        !await fileSystem.entityForUri(sdkRoot).exists()) {
+      reportError("SDK root directory not found: ${sdkRoot}");
       return false;
     }
 
-    if (root != null && !await fs.entityForUri(root).exists()) {
-      return _report("SDK root directory not found: ${_raw.sdkRoot}");
+    var summary = sdkSummary;
+    if (summary != null && !await fileSystem.entityForUri(summary).exists()) {
+      reportError("SDK summary not found: ${summary}");
+      return false;
     }
 
-    var summary = _raw.sdkSummary;
-    if (summary != null && !await fs.entityForUri(summary).exists()) {
-      return _report("SDK summary not found: ${_raw.sdkSummary}");
+    if (compileSdk && summary != null) {
+      reportError(
+          "The compileSdk and sdkSummary options are mutually exclusive");
+      return false;
     }
-
-    // TODO(sigmund): add checks for options that are meant to be disjoint (like
-    // sdkRoot and sdkSummary).
     return true;
   }
 
@@ -87,43 +148,67 @@ class ProcessedOptions {
   /// whole-program.
   bool get compileSdk => _raw.compileSdk;
 
+  FileSystem _fileSystem;
+
   /// Get the [FileSystem] which should be used by the front end to access
   /// files.
   ///
   /// If the client supplied roots using [CompilerOptions.multiRoots], the
   /// returned [FileSystem] will automatically perform the appropriate mapping.
-  FileSystem get fileSystem {
-    // TODO(paulberry): support multiRoots.
-    assert(_raw.multiRoots.isEmpty);
-    return _raw.fileSystem;
-  }
+  FileSystem get fileSystem => _fileSystem ??= _createFileSystem();
 
   /// Whether to interpret Dart sources in strong-mode.
   bool get strongMode => _raw.strongMode;
 
-  /// Get an outline program that summarizes the SDK.
-  Future<Program> get sdkSummaryProgram async {
+  Target _target;
+  Target get target => _target ??=
+      _raw.target ?? new VmFastaTarget(new TargetFlags(strongMode: strongMode));
+
+  /// Get an outline program that summarizes the SDK, if any.
+  // TODO(sigmund): move, this doesn't feel like an "option".
+  Future<Program> loadSdkSummary(CanonicalName nameRoot) async {
     if (_sdkSummaryProgram == null) {
-      if (_raw.sdkSummary == null) return null;
-      _sdkSummaryProgram = await _loadProgram(_raw.sdkSummary);
+      if (sdkSummary == null) return null;
+      var bytes = await fileSystem.entityForUri(sdkSummary).readAsBytes();
+      _sdkSummaryProgram = loadProgram(bytes, nameRoot);
     }
     return _sdkSummaryProgram;
   }
 
   /// Get the summary programs for each of the underlying `inputSummaries`
   /// provided via [CompilerOptions].
-  Future<List<Program>> get inputSummariesPrograms async {
+  // TODO(sigmund): move, this doesn't feel like an "option".
+  Future<List<Program>> loadInputSummaries(CanonicalName nameRoot) async {
     if (_inputSummariesPrograms == null) {
       var uris = _raw.inputSummaries;
       if (uris == null || uris.isEmpty) return const <Program>[];
-      _inputSummariesPrograms = await Future.wait(uris.map(_loadProgram));
+      // TODO(sigmund): throttle # of concurrent opreations.
+      var allBytes = await Future
+          .wait(uris.map((uri) => fileSystem.entityForUri(uri).readAsBytes()));
+      _inputSummariesPrograms =
+          allBytes.map((bytes) => loadProgram(bytes, nameRoot)).toList();
     }
     return _inputSummariesPrograms;
   }
 
-  Future<Program> _loadProgram(Uri uri) async {
-    var bytes = await fileSystem.entityForUri(uri).readAsBytes();
-    return loadProgramFromBytes(bytes)..unbindCanonicalNames();
+  /// Load each of the [CompilerOptions.linkedDependencies] programs.
+  // TODO(sigmund): move, this doesn't feel like an "option".
+  Future<List<Program>> loadLinkDependencies(CanonicalName nameRoot) async {
+    if (_linkedDependencies == null) {
+      var uris = _raw.linkedDependencies;
+      if (uris == null || uris.isEmpty) return const <Program>[];
+      // TODO(sigmund): throttle # of concurrent opreations.
+      var allBytes = await Future
+          .wait(uris.map((uri) => fileSystem.entityForUri(uri).readAsBytes()));
+      _linkedDependencies =
+          allBytes.map((bytes) => loadProgram(bytes, nameRoot)).toList();
+    }
+    return _linkedDependencies;
+  }
+
+  /// Helper to load a .dill file from [uri] using the existing [nameRoot].
+  Program loadProgram(List<int> bytes, CanonicalName nameRoot) {
+    return loadProgramFromBytes(bytes, new Program(nameRoot: nameRoot));
   }
 
   /// Get the [TranslateUri] which resolves "package:" and "dart:" URIs.
@@ -135,13 +220,19 @@ class ProcessedOptions {
       await _getPackages();
       // TODO(scheglov) Load SDK libraries from whatever format we decide.
       // TODO(scheglov) Remove the field "_raw.dartLibraries".
-      _uriTranslator = new TranslateUri(
-          _packages, _raw.dartLibraries, const <String, List<Uri>>{});
-      _uriTranslator.dartLibraries.addAll(_raw.dartLibraries);
+      var libraries = _raw.dartLibraries ?? await _parseLibraries();
+      _uriTranslator =
+          new TranslateUri(_packages, libraries, const <String, List<Uri>>{});
+      ticker.logMs("Read packages file");
     }
     return _uriTranslator;
   }
 
+  Future<Map<String, Uri>> _parseLibraries() async {
+    Uri librariesJson = _raw.sdkRoot?.resolve("lib/libraries.json");
+    return await computeLibraries(fileSystem, librariesJson);
+  }
+
   /// Get the package map which maps package names to URIs.
   ///
   /// This is an asynchronous getter since file system operations may be
@@ -149,7 +240,8 @@ class ProcessedOptions {
   Future<Map<String, Uri>> _getPackages() async {
     if (_packages == null) {
       if (_raw.packagesFileUri == null) {
-        throw new UnimplementedError(); // TODO(paulberry): search for .packages
+        // TODO(sigmund,paulberry): implement
+        throw new UnimplementedError('search for .packages');
       } else if (_raw.packagesFileUri.path.isEmpty) {
         _packages = {};
       } else {
@@ -162,9 +254,6 @@ class ProcessedOptions {
   }
 
   /// Get the location of the SDK.
-  ///
-  /// This is an asynchronous getter since file system operations may be
-  /// required to locate the SDK.
   Uri _normalizeSdkRoot() {
     // If an SDK summary location was provided, the SDK itself should not be
     // needed.
@@ -172,12 +261,89 @@ class ProcessedOptions {
     if (_raw.sdkRoot == null) {
       // TODO(paulberry): implement the algorithm for finding the SDK
       // automagically.
-      throw new UnimplementedError();
+      throw new UnimplementedError('infer the default sdk location');
     }
     var root = _raw.sdkRoot;
     if (!root.path.endsWith('/')) {
-      root = root.replace(path: _sdkRoot.path + '/');
+      root = root.replace(path: root.path + '/');
     }
     return root;
   }
+
+  /// Get or infer the location of the SDK summary.
+  Uri _computeSdkSummaryUri() {
+    if (_raw.sdkSummary != null) return _raw.sdkSummary;
+
+    // Infer based on the sdkRoot, but only when `compileSdk` is false,
+    // otherwise the default intent was to compile the sdk from sources and not
+    // to load an sdk summary file.
+    if (_raw.compileSdk) return null;
+    return sdkRoot.resolve('outline.dill');
+  }
+
+  /// Create a [FileSystem] specific to the current options.
+  ///
+  /// If [chaseDependencies] is false, the resulting file system will be
+  /// hermetic.
+  FileSystem _createFileSystem() {
+    var result = _raw.fileSystem;
+    if (!chaseDependencies) {
+      var allInputs = inputs.toSet();
+      allInputs.addAll(_raw.inputSummaries);
+      allInputs.addAll(_raw.linkedDependencies);
+
+      if (sdkSummary != null) allInputs.add(sdkSummary);
+
+      if (_raw.sdkRoot != null) {
+        // TODO(sigmund): refine this, we should be more explicit about when
+        // sdkRoot and libraries.json are allowed to be used.
+        allInputs.add(sdkRoot);
+        allInputs.add(sdkRoot.resolve("lib/libraries.json"));
+      }
+
+      /// Note: Searching the file-system for the package-config is not
+      /// supported in hermetic builds.
+      if (_raw.packagesFileUri != null) allInputs.add(_raw.packagesFileUri);
+      result = new HermeticFileSystem(allInputs, result);
+    }
+    // TODO(paulberry): support multiRoots.
+    assert(_raw.multiRoots.isEmpty);
+    return result;
+  }
+}
+
+/// A [FileSystem] that only allows access to files that have been explicitly
+/// whitelisted.
+class HermeticFileSystem implements FileSystem {
+  final Set<Uri> includedFiles;
+  final FileSystem _realFileSystem;
+
+  HermeticFileSystem(this.includedFiles, this._realFileSystem);
+
+  FileSystemEntity entityForUri(Uri uri) {
+    if (includedFiles.contains(uri)) return _realFileSystem.entityForUri(uri);
+    throw new HermeticAccessException(uri);
+  }
+}
+
+class HermeticAccessException extends FileSystemException {
+  HermeticAccessException(Uri uri)
+      : super(
+            uri,
+            'Invalid access to $uri: '
+            'the file is accessed in a modular hermetic build, '
+            'but it was not explicitly listed as an input.');
+
+  @override
+  String toString() => message;
+}
+
+/// An error that only contains a message and no error location.
+class _CompilationError implements CompilationError {
+  String get correction => null;
+  SourceSpan get span => null;
+  final String message;
+  _CompilationError(this.message);
+
+  String toString() => message;
 }