Use sdk summaries in front_end/kernel_generator.

pkg/front_end/lib/kernel_generator.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Defines the front-end API for converting source code to Dart Kernel objects.
 library front_end.kernel_generator;
 
 import 'compilation_error.dart';
 import 'compiler_options.dart';
 import 'dart:async';
 
+import 'package:analyzer/src/generated/source.dart' show SourceKind;
+import 'package:analyzer/src/summary/package_bundle_reader.dart'
+    show InSummarySource;
 // TODO(sigmund): move loader logic under front_end/lib/src/kernel/
 import 'package:kernel/analyzer/loader.dart';
 import 'package:kernel/kernel.dart';
 import 'package:source_span/source_span.dart' show SourceSpan;
 
 /// Generates a kernel representation of the program whose main library is in
 /// the given [source].
 ///
 /// Intended for whole program (non-modular) compilation.
 ///
 /// Given the Uri of a file containing a program's `main` method, this function
 /// follows `import`, `export`, and `part` declarations to discover the whole
 /// program, and converts the result to Dart Kernel format.
 ///
+/// If `compileSdk` in [options] is true, the generated program will include
+/// code for the SDK.
+///
 /// If summaries are provided in [options], they may be used to speed up
-/// analysis, but they will not take the place of Dart source code (since the
-/// Dart source code is still needed to access the contents of method bodies).
-///
-/// TODO(paulberry): will the VM have a pickled version of the SDK inside it? If
-/// so, then maybe this method should not convert SDK libraries to kernel.
+/// analysis. If in addition `compileSdk` is false, this will speed up
+/// compilation, as no source of the sdk will be generated.  Note however, that
+/// summaries for application code can also speed up analysis, but they will not
+/// take the place of Dart source code (since the Dart source code is still
+/// needed to access the contents of method bodies).
 Future<Program> kernelForProgram(Uri source, CompilerOptions options) async {
-  var loader = await _createLoader(options);
-  Program program = loader.loadProgram(source);
+  var loader = await _createLoader(options, entry: source);
+  // TODO(sigmund): merge what we have in loadEverything and the logic below in
+  // kernelForBuildUnit so there is a single place where we crawl for
+  // dependencies.
+  Program program = loader.loadProgram(source, compileSdk: options.compileSdk);
   _reportErrors(loader.errors, options.onError);
   return program;
 }
 
-/// Generates a kernel representation of the build unit whose source files are
-/// in [sources].
+/// Generates a kernel representation for a build unit.
 ///
 /// Intended for modular compilation.
 ///
-/// [sources] should be the complete set of source files for a build unit
-/// (including both library and part files).  All of the library files are
-/// transformed into Dart Kernel Library objects.
+/// The build unit by default contains only the source files in [sources]
+/// (including library and part files), but if
+/// [CompilerOptions.chaseDependencies] is true, it may include some additional
+/// source files.  All of the library files are transformed into Dart Kernel
+/// Library objects.
 ///
-/// The compilation process is hermetic, meaning that the only files which will
-/// be read are those listed in [sources], [CompilerOptions.inputSummaries], and
-/// [CompilerOptions.sdkSummary].  If a source file attempts to refer to a file
-/// which is not obtainable from these paths, that will result in an error, even
-/// if the file exists on the filesystem.
+/// By default, the compilation process is hermetic, meaning that the only files
+/// which will be read are those listed in [sources],
+/// [CompilerOptions.inputSummaries], and [CompilerOptions.sdkSummary].  If a
+/// source file attempts to refer to a file which is not obtainable from these
+/// paths, that will result in an error, even if the file exists on the
+/// filesystem.
+///
+/// When [CompilerOptions.chaseDependencies] is true, this default behavior
+/// changes, and any dependency of [sources] that is not listed in
+/// [CompilerOptions.inputSummaries] and [CompilerOptions.sdkSummary] is treated
+/// as an additional source file for the build unit.
 ///
 /// Any `part` declarations found in [sources] must refer to part files which
-/// are also listed in [sources], otherwise an error results.  (It is not
-/// permitted to refer to a part file declared in another build unit).
+/// are also listed in the build unit sources, otherwise an error results.  (It
+/// is not permitted to refer to a part file declared in another build unit).
 ///
 /// The return value is a [Program] object with no main method set.
 /// TODO(paulberry): would it be better to define a data type in kernel to
 /// represent a bundle of all the libraries in a given build unit?
 ///
 /// TODO(paulberry): does additional information need to be output to allow the
 /// caller to match up referenced elements to the summary files they were
 /// obtained from?
 Future<Program> kernelForBuildUnit(
-        List<Uri> sources, CompilerOptions options) async {
+    List<Uri> sources, CompilerOptions options) async {
   var repository = new Repository();
   var loader = await _createLoader(options, repository: repository);
-  // TODO(sigmund): add special handling for part files.
-  sources.forEach(loader.loadLibrary);
+  var context = loader.context;
+
+  // Process every library in the build unit.
+  for (var uri in sources) {
+    var source = context.sourceFactory.forUri2(uri);
+    //  We ignore part files, those are handled by their enclosing library.
+    if (context.computeKindOf(source) == SourceKind.PART) {
+      // TODO(sigmund): record it and ensure that this part is within a provided
+      // library.
+      continue;
+    }
+    loader.loadLibrary(uri);
+  }
+
+  // Check whether all dependencies were included in [sources].
+  // TODO(sigmund): we should look for dependencies using import, export, and
+  // part directives intead of relying on the dartk-loader.  In particular, if a
+  // library is imported but not used, the logic below will not detect it.
+  for (int i = 0; i < repository.libraries.length; ++i) {
+    // Note: we don't use a for-in loop because repository.libraries grows as
+    // the loader processes libraries.
+    var lib = repository.libraries[i];
+    var source = context.sourceFactory.forUri2(lib.importUri);
+    if (source is InSummarySource) continue;
+    if (options.chaseDependencies) {
+      loader.ensureLibraryIsLoaded(lib);
+    } else if (lib.isExternal) {
+      // Default behavior: the build should be hermetic and all dependencies
+      // should be listed.
+      options.onError(new _DartkError('hermetic build error: '
+          'no source or summary was given for ${lib.importUri}'));
+    }
+  }
+
   Program program = new Program(repository.libraries);
   _reportErrors(loader.errors, options.onError);
   return program;
 }
 
+/// Create a [DartLoader] using the provided [options].
+///
+/// If [options] contain no configuration to resolve `.packages`, the [entry]
+/// file will be used to search for a `.packages` file.
 Future<DartLoader> _createLoader(CompilerOptions options,
-    {Repository repository}) async {
+    {Repository repository, Uri entry}) async {
   var kernelOptions = _convertOptions(options);
-  var packages = await createPackages(options.packagesFilePath);
+  var packages = await createPackages(options.packagesFilePath,
+      discoveryPath: entry?.path);
   return new DartLoader(
       repository ?? new Repository(), kernelOptions, packages);
 }
 
 DartOptions _convertOptions(CompilerOptions options) {
   return new DartOptions(
+      strongMode: options.strongMode,
       sdk: options.sdkPath,
+      // TODO(sigmund): make it possible to use summaries and still compile the
+      // sdk sources.
+      sdkSummary: options.compileSdk ? null : options.sdkSummary,
       packagePath: options.packagesFilePath,
       declaredVariables: options.declaredVariables);
 }
 
 void _reportErrors(List errors, ErrorHandler onError) {
   if (onError == null) return;
   for (var error in errors) {
     onError(new _DartkError(error));
   }
 }
 
 // TODO(sigmund): delete this class. Dartk should not format errors itself, we
 // should just pass them along.
 class _DartkError implements CompilationError {
   String get correction => null;
   SourceSpan get span => null;
   final String message;
   _DartkError(this.message);
 }