Improve recovery from compile-time errors.

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;
 
 import 'package:front_end/file_system.dart';
+
 import 'package:kernel/ast.dart'
     show
         Arguments,
         CanonicalName,
         Class,
         Constructor,
         DartType,
         DynamicType,
         EmptyStatement,
         Expression,
         ExpressionStatement,
         Field,
         FieldInitializer,
         FunctionNode,
         Initializer,
         InvalidInitializer,
         Library,
+        ListLiteral,
         Name,
         NamedExpression,
         NullLiteral,
         ProcedureKind,
         Program,
         Source,
         StringLiteral,
         SuperInitializer,
         Throw,
         TypeParameter,
@@ skipping 63 matching lines @@
   KernelTarget(
       this.fileSystem, DillTarget dillTarget, TranslateUri uriTranslator,
       [Map<String, Source> uriToSource])
       : dillTarget = dillTarget,
         uriToSource = uriToSource ?? CompilerContext.current.uriToSource,
         super(dillTarget.ticker, uriTranslator, dillTarget.backendTarget) {
     resetCrashReporting();
     loader = createLoader();
   }
 
-  bool get hasErrors {
-    return errors.isNotEmpty || loader.collectCompileTimeErrors().isNotEmpty;
-  }
-
   void addError(file, int charOffset, String message) {
     Uri uri = file is String ? Uri.parse(file) : file;
     InputError error = new InputError(uri, charOffset, message);
     String formatterMessage = error.format();
     print(formatterMessage);
     errors.add(formatterMessage);
   }
 
   SourceLoader<Library> createLoader() =>
       new SourceLoader<Library>(fileSystem, this);
@@ skipping 152 matching lines @@
       handleInputError(null,
           isFullProgram: true, trimDependencies: trimDependencies);
       return program;
     }
 
     try {
       await loader.buildBodies();
       loader.finishStaticInvocations();
       finishAllConstructors();
       loader.finishNativeMethods();
-      if (!hasErrors) {
-        runBuildTransformations();
-      }
+      runBuildTransformations();
 
       if (verify) this.verify();
-      errors.addAll(loader.collectCompileTimeErrors().map((e) => e.format()));
       if (errors.isNotEmpty) {
         handleInputError(null,
             isFullProgram: true, trimDependencies: trimDependencies);
       }
+      handleRecoverableErrors(loader.unhandledErrors);
     } on InputError catch (e) {
       handleInputError(e,
           isFullProgram: true, trimDependencies: trimDependencies);
     } catch (e, s) {
       return reportCrash(e, s, loader?.currentUriForCrashReporting);
     }
     if (trimDependencies) trimDependenciesInProgram();
     return program;
   }
 
@@ skipping 34 matching lines @@
     }
     for (String path in allDependencies) {
       sb.write(" ");
       sb.write(path);
     }
     sb.writeln();
     await new File.fromUri(depsFile).writeAsString("$sb");
     ticker.logMs("Wrote deps file");
   }
 
+  /// Adds a synthetic field named `#errors` to the main library that contains
+  /// [recoverableErrors] formatted.
+  ///
+  /// If [recoverableErrors] is empty, this method does nothing.
+  ///
+  /// If there's no main library, this method uses [erroneousProgram] to
+  /// replace [program].
+  void handleRecoverableErrors(List<InputError> recoverableErrors) {
+    if (recoverableErrors.isEmpty) return;
+    KernelLibraryBuilder mainLibrary = loader.first;
+    if (mainLibrary == null) {
+      program = erroneousProgram(true);
+      return;
+    }
+    List<Expression> expressions = <Expression>[];
+    for (InputError error in recoverableErrors) {
+      String message = error.format();
+      errors.add(message);
+      expressions.add(new StringLiteral(message));
+    }
+    mainLibrary.library.addMember(new Field(new Name("#errors"),
+        initializer: new ListLiteral(expressions, isConst: true),
+        isConst: true));
+  }
+
   Program erroneousProgram(bool isFullProgram) {
     Uri uri = loader.first?.uri ?? Uri.parse("error:error");
     Uri fileUri = loader.first?.fileUri ?? uri;
     KernelLibraryBuilder library =
         new KernelLibraryBuilder(uri, fileUri, loader, false);
     loader.first = library;
     if (isFullProgram) {
       // If this is an outline, we shouldn't add an executable main
       // method. Similarly considerations apply to separate compilation. It
       // could also make sense to add a way to mark .dill files as having
@@ skipping 343 matching lines @@
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }