Avoid creating invalid TypeMask.nonNullExact

pkg/compiler/lib/src/universe/class_set.dart

 // Copyright (c) 2015, 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 dart2js.world.class_set;
 
 import 'dart:collection' show IterableBase;
 import '../elements/elements.dart' show ClassElement;
 import '../util/util.dart' show Link;
 
@@ skipping 84 matching lines @@
        bool strict: false}) {
     return new ClassHierarchyNodeIterable(
         this,
         includeRoot: !strict,
         includeDirectlyInstantiated: includeDirectlyInstantiated,
         includeIndirectlyInstantiated: includeIndirectlyInstantiated,
         includeUninstantiated: includeUninstantiated);
   }
 
   void printOn(StringBuffer sb, String indentation,
-               {bool instantiatedOnly: false}) {
+               {bool instantiatedOnly: false,
+                ClassElement withRespectTo}) {
+
+    bool isRelatedTo(ClassElement subclass) {
+      return subclass.implementsInterface(withRespectTo);
+    }
+
     sb.write('$indentation$cls');
     if (isDirectlyInstantiated) {
       sb.write(' directly');
     }
     if (isIndirectlyInstantiated) {
       sb.write(' indirectly');
     }
     sb.write(' [');
     if (_directSubclasses.isEmpty) {
       sb.write(']');
     } else {
       bool needsComma = false;
       for (Link<ClassHierarchyNode> link = _directSubclasses;
            !link.isEmpty;
            link = link.tail) {
-        if (instantiatedOnly && !link.head.isInstantiated) {
+        ClassHierarchyNode child = link.head;
+        if (instantiatedOnly && !child.isInstantiated) {
           continue;
         }
+        if (withRespectTo != null) {

[floitsch, 2015/10/13 12:15:42]

if (withRespectTo != null && !child.subclasses().any(isRelatedTo)) {
  continue;
}

[Johnni Winther, 2015/10/13 13:06:37]

Done.

+          if (!child.subclasses().any(isRelatedTo)) {
+            continue;
+          }
+        }
         if (needsComma) {
           sb.write(',\n');
         } else {
           sb.write('\n');
         }
-        link.head.printOn(
-            sb, '$indentation  ', instantiatedOnly: instantiatedOnly);
+        child.printOn(
+            sb,
+            '$indentation  ',
+            instantiatedOnly: instantiatedOnly,
+            withRespectTo: withRespectTo);
         needsComma = true;
       }
       if (needsComma) {
         sb.write('\n');
         sb.write('$indentation]');
       } else {
         sb.write(']');
       }
     }
   }
 
-  String dump({String indentation: '', bool instantiatedOnly: false}) {
+  String dump({String indentation: '',
+               bool instantiatedOnly: false,
+               ClassElement withRespectTo}) {
     StringBuffer sb = new StringBuffer();
-    printOn(sb, indentation, instantiatedOnly: instantiatedOnly);
+    printOn(sb, indentation,
+        instantiatedOnly: instantiatedOnly,
+        withRespectTo: withRespectTo);
     return sb.toString();
   }
 
   String toString() => cls.toString();
 }
 
 /// Object holding the subclass and subtype relation for a single
 /// [ClassElement].
 ///
 /// The subclass relation for a class `C` is modelled through a reference to
@@ skipping 337 matching lines @@
           includeDirectlyInstantiated: includeDirectlyInstantiated,
           includeIndirectlyInstantiated: includeIndirectlyInstantiated,
           includeUninstantiated: includeUninstantiated).iterator;
       if (elements.moveNext()) {
         return true;
       }
     }
     return false;
   }
 }