Transform async code only for source libraries.

pkg/front_end/lib/src/fasta/kernel/kernel_target.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.
 
 library fasta.kernel_target;
 
 import 'dart:async' show Future;
 
 import 'dart:io' show File;
 
@@ skipping 80 matching lines @@
   final FileSystem fileSystem;
 
   final bool strongMode;
 
   final DillTarget dillTarget;
 
   /// Shared with [CompilerContext].
   final Map<String, Source> uriToSource;
 
   SourceLoader<Library> loader;
-  Program _program;
+  Program program;
 
   final List<String> errors = <String>[];
 
   final TypeBuilder dynamicType =
       new KernelNamedTypeBuilder("dynamic", null, -1, null);
 
   KernelTarget(this.fileSystem, DillTarget dillTarget,
       TranslateUri uriTranslator, this.strongMode,
       [Map<String, Source> uriToSource])
       : dillTarget = dillTarget,
@@ skipping 104 matching lines @@
     builder.mixedInType = null;
   }
 
   void handleInputError(InputError error,
       {bool isFullProgram, bool trimDependencies: false}) {
     if (error != null) {
       String message = error.format();
       print(message);
       errors.add(message);
     }
-    _program = erroneousProgram(isFullProgram);
+    program = erroneousProgram(isFullProgram);
   }
 
   @override
   Future<Program> buildOutlines({CanonicalName nameRoot}) async {
     if (loader.first == null) return null;
     try {
       loader.createTypeInferenceEngine();
       await loader.buildOutlines();
       loader.coreLibrary
           .becomeCoreLibrary(const DynamicType(), const VoidType());
       dynamicType.bind(loader.coreLibrary["dynamic"]);
       loader.resolveParts();
       loader.computeLibraryScopes();
       loader.resolveTypes();
       loader.checkSemantics();
       loader.buildProgram();
       List<SourceClassBuilder> sourceClasses = collectAllSourceClasses();
       installDefaultSupertypes();
       installDefaultConstructors(sourceClasses);
       loader.resolveConstructors();
       loader.finishTypeVariables(objectClassBuilder);
-      _program =
+      program =
           link(new List<Library>.from(loader.libraries), nameRoot: nameRoot);
-      loader.computeHierarchy(_program);
+      loader.computeHierarchy(program);
       loader.checkOverrides(sourceClasses);
       loader.prepareInitializerInference();
       loader.performInitializerInference();
     } on InputError catch (e) {
       handleInputError(e, isFullProgram: false);
     } catch (e, s) {
       return reportCrash(e, s, loader?.currentUriForCrashReporting);
     }
-    return _program;
+    return program;
   }
 
   /// Build the kernel representation of the program loaded by this target. The
   /// program will contain full bodies for the code loaded from sources, and
   /// only references to the code loaded by the [DillTarget], which may or may
   /// not include method bodies (depending on what was loaded into that target,
   /// an outline or a full kernel program).
   ///
   /// When [trimDependencies] is true, this also runs a tree-shaker that deletes
   /// anything from the [DillTarget] that is not needed for the source program,
   /// this includes function bodies and types that are not reachable.
   ///
   /// If [verify], run the default kernel verification on the resulting program.
   @override
   Future<Program> buildProgram(
       {bool verify: false, bool trimDependencies: false}) async {
     if (loader.first == null) return null;
     if (errors.isNotEmpty) {
       handleInputError(null,
           isFullProgram: true, trimDependencies: trimDependencies);
       if (trimDependencies) trimDependenciesInProgram();
-      return _program;
+      return program;
     }
 
     try {
       await loader.buildBodies();
       loader.finishStaticInvocations();
       finishAllConstructors();
       loader.finishNativeMethods();
       runBuildTransformations();
 
       if (verify) this.verify();
       errors.addAll(loader.collectCompileTimeErrors().map((e) => e.format()));
       if (errors.isNotEmpty) {
         handleInputError(null,
             isFullProgram: true, trimDependencies: trimDependencies);
       }
     } on InputError catch (e) {
       handleInputError(e,
           isFullProgram: true, trimDependencies: trimDependencies);
     } catch (e, s) {
       return reportCrash(e, s, loader?.currentUriForCrashReporting);
     }
     if (trimDependencies) trimDependenciesInProgram();
-    return _program;
+    return program;
   }
 
   Future writeDepsFile(Uri output, Uri depsFile,
       {Iterable<Uri> extraDependencies}) async {
     String toRelativeFilePath(Uri uri) {
       // Ninja expects to find file names relative to the current working
       // directory. We've tried making them relative to the deps file, but that
       // doesn't work for downstream projects. Making them absolute also
       // doesn't work.
       //
@@ skipping 338 matching lines @@
   }
 
   /// Run all transformations that are needed when building a program for the
   /// first time.
   void runBuildTransformations() {
     transformMixinApplications();
     otherTransformations();
   }
 
   void transformMixinApplications() {
-    new MixinFullResolution(backendTarget).transform(_program);
+    new MixinFullResolution(backendTarget).transform(program);
     ticker.logMs("Transformed mixin applications");
   }
 
   void otherTransformations() {
     // TODO(ahe): Don't generate type variables in the first place.
     if (!strongMode) {
-      _program.accept(new Erasure());
+      program.accept(new Erasure());
       ticker.logMs("Erased type variables in generic methods");
     }
     // TODO(kmillikin): Make this run on a per-method basis.
-    transformAsync.transformProgram(_program);
+    transformAsync.transformProgram(program);
     ticker.logMs("Transformed async methods");
   }
 
   void verify() {
-    var verifyErrors = verifyProgram(_program);
+    var verifyErrors = verifyProgram(program);
     errors.addAll(verifyErrors.map((error) => '$error'));
     ticker.logMs("Verified program");
   }
 
   /// Tree-shakes most code from the [dillTarget] by visiting all other
-  /// libraries in [_program] and marking the APIs from the [dillTarget]
+  /// libraries in [program] and marking the APIs from the [dillTarget]
   /// libraries that are in use.
   trimDependenciesInProgram() {
     var toShake =
         dillTarget.loader.libraries.map((lib) => lib.importUri).toSet();
     var isIncluded = (Uri uri) => !toShake.contains(uri);
     var data = new RetainedDataBuilder();
     // TODO(sigmund): replace this step with data that is directly computed from
     // the builders: we should know the tree-shaking roots without having to do
     // a second visit over the tree.
-    new RootsMarker(data).run(_program, isIncluded);
-    trimProgram(_program, data, isIncluded);
+    new RootsMarker(data).run(program, isIncluded);
+    trimProgram(program, data, isIncluded);
   }
 
   /// Return `true` if the given [library] was built by this [KernelTarget]
   /// from sources, and not loaded from a [DillTarget].
   bool isSourceLibrary(Library library) {
     return loader.libraries.contains(library);
   }
 }
 
 /// Looks for a constructor call that matches `super()` from a constructor in
 /// [cls]. Such a constructor may have optional arguments, but no required
 /// arguments.
 Constructor defaultSuperConstructor(Class cls) {
   Class superclass = cls.superclass;
   while (superclass != null && superclass.isMixinApplication) {
     superclass = superclass.superclass;
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }