Report errors on non-final fields in const classes.

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, IOSink;
 
@@ skipping 96 matching lines @@
 
   KernelTarget(DillTarget dillTarget, TranslateUri uriTranslator,
       [Map<String, Source> uriToSource])
       : dillTarget = dillTarget,
         uriToSource = uriToSource ?? CompilerContext.current.uriToSource,
         super(dillTarget.ticker, uriTranslator) {
     resetCrashReporting();
     loader = createLoader();
   }
 
+  void addError(file, int charOffset, String message) {
+    Uri uri = file is String ? Uri.parse(file) : file;
+    InputError error = new InputError(uri, charOffset, message);
+    print(error.format());
+    errors.add(error);
+  }
+
   SourceLoader<Library> createLoader() => new SourceLoader<Library>(this);
 
   void addSourceInformation(
       Uri uri, List<int> lineStarts, List<int> sourceCode) {
     String fileUri = relativizeUri(uri);
     uriToSource[fileUri] = new Source(lineStarts, sourceCode);
   }
 
   void read(Uri uri) {
     loader.read(uri);
@@ skipping 417 matching lines @@
     ticker.logMs("Finished constructors");
   }
 
   /// Ensure constructors of [cls] have the correct initializers and other
   /// requirements.
   void finishConstructors(Class cls) {
     /// Quotes below are from [Dart Programming Language Specification, 4th
     /// Edition](http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-408.pdf):
     Constructor superTarget;
     List<Field> uninitializedFields = <Field>[];
+    List<Field> nonFinalFields = <Field>[];
     for (Field field in cls.fields) {
+      if (field.isInstanceMember && !field.isFinal) {
+        nonFinalFields.add(field);
+      }
       if (field.initializer == null) {
         uninitializedFields.add(field);
       }
     }
     Map<Constructor, List<FieldInitializer>> fieldInitializers =
         <Constructor, List<FieldInitializer>>{};
     for (Constructor constructor in cls.constructors) {
       if (!isRedirectingGenerativeConstructor(constructor)) {
         /// >If no superinitializer is provided, an implicit superinitializer
         /// >of the form super() is added at the end of k’s initializer list,
         /// >unless the enclosing class is class Object.
         if (!constructor.initializers.any(isSuperinitializerOrInvalid)) {
           superTarget ??= defaultSuperConstructor(cls);
           Initializer initializer;
           if (superTarget == null) {
-            Uri uri = constructor.enclosingClass.fileUri == null
-                ? null
-                : Uri.parse(constructor.enclosingClass.fileUri);
-            InputError error = new InputError(
-                uri,
+            addError(
+                constructor.enclosingClass.fileUri,
                 constructor.fileOffset,
                 "${cls.superclass.name} has no constructor that takes zero"
                 " arguments.");
-            print(error.format());
-            errors.add(error);
             initializer = new InvalidInitializer();
           } else {
             initializer =
                 new SuperInitializer(superTarget, new Arguments.empty());
           }
           constructor.initializers.add(initializer);
           initializer.parent = constructor;
         }
         if (constructor.function.body == null) {
           /// >If a generative constructor c is not a redirecting constructor
           /// >and no body is provided, then c implicitly has an empty body {}.
           /// We use an empty statement instead.
           constructor.function.body = new EmptyStatement();
           constructor.function.body.parent = constructor.function;
         }
         List<FieldInitializer> myFieldInitializers = <FieldInitializer>[];
         for (Initializer initializer in constructor.initializers) {
           if (initializer is FieldInitializer) {
             myFieldInitializers.add(initializer);
           }
         }
         fieldInitializers[constructor] = myFieldInitializers;
+        if (constructor.isConst && nonFinalFields.isNotEmpty) {
+          addError(constructor.enclosingClass.fileUri, constructor.fileOffset,
+              "Constructor is marked 'const' so all fields must be final.");
+          for (Field field in nonFinalFields) {
+            addError(constructor.enclosingClass.fileUri, field.fileOffset,
+                "Field isn't final, but constructor is 'const'.");
+          }
+          nonFinalFields.clear();
+        }
       }
     }
     Set<Field> initializedFields;
     fieldInitializers.forEach(
         (Constructor constructor, List<FieldInitializer> initializers) {
       Iterable<Field> fields = initializers.map((i) => i.field);
       if (initializedFields == null) {
         initializedFields = new Set<Field>.from(fields);
       } else {
         initializedFields.addAll(fields);
@@ skipping 72 matching lines @@
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }