Transform async code only for source libraries.

pkg/front_end/lib/src/incremental_kernel_generator_impl.dart

Index: pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
diff --git a/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart b/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
index 05e88e2a392f24d2618374ace8f9a5bb9c041adf..bb8089ab8147d3204244c321d3e43990f2cca5c3 100644
--- a/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
+++ b/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
@@ -17,9 +17,14 @@ 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/incremental/file_state.dart';
+import 'package:kernel/ast.dart';
 import 'package:kernel/binary/ast_from_binary.dart';
 import 'package:kernel/binary/ast_to_binary.dart';
 import 'package:kernel/kernel.dart' hide Source;
+import 'package:kernel/transformations/continuation.dart' as transformAsync;
+import 'package:kernel/transformations/erasure.dart' as transformErasure;
+import 'package:kernel/transformations/mixin_full_resolution.dart'
+    as transformMixin;
 
 dynamic unimplemented() {
   // TODO(paulberry): get rid of this.
@@ -203,7 +208,7 @@ class IncrementalKernelGeneratorImpl implements IncrementalKernelGenerator {
       }
 
       // Create KernelTarget and configure it for compiling the cycle URIs.
-      KernelTarget kernelTarget = new KernelTarget(_fsState.fileSystemView,
+      var kernelTarget = new _IncrementalKernelTarget(_fsState.fileSystemView,
           dillTarget, _uriTranslator, _options.strongMode);
       for (FileState library in cycle.libraries) {
         kernelTarget.read(library.uri);
@@ -290,6 +295,24 @@ class IncrementalKernelGeneratorImpl implements IncrementalKernelGenerator {
   }
 }
 
+class _IncrementalKernelTarget extends KernelTarget {
+  _IncrementalKernelTarget(FileSystem fileSystem, DillTarget dillTarget,
+      TranslateUri uriTranslator, bool strongMode)
+      : super(fileSystem, dillTarget, uriTranslator, strongMode);
+
+  @override
+  void runBuildTransformations() {

[Siggi Cherem (dart-lang), 2017/05/23 22:06:17]

Not sure if we need this subclass: even outside the incremental generator, I
believe we should only apply transformations to sourcelibraries and not to code
loaded from the dillTarget (since we overall expect the dillTarget to only have
outlines anyways)

I'd be inclined to simply modify the call to transformProgram directly in
KernelTarget. Peter - do you agree?

+    // TODO(scheglov) apply only to source libraries
+    new transformMixin.MixinFullResolution(backendTarget).transform(program);
+    if (!strongMode) {
+      program.accept(new transformErasure.Erasure());
+    }
+    // Transform only source libraries.
+    // Dill libraries have already been transformed.
+    transformAsync.transformProgram(program, libraryFilter: isSourceLibrary);
+  }
+}
+
 /// Compilation result for a library cycle.
 class _LibraryCycleResult {
   final LibraryCycle cycle;