Issue 26096. Explicitly compute the result that ensures that directives are resolved in units.

pkg/analyzer/lib/src/task/dart.dart

Index: pkg/analyzer/lib/src/task/dart.dart
diff --git a/pkg/analyzer/lib/src/task/dart.dart b/pkg/analyzer/lib/src/task/dart.dart
index bd548cb59485e7d5b1d05e994782e4c888f81c67..88c44fe23c9c9f09e781f032794e80c21c95ed8b 100644
--- a/pkg/analyzer/lib/src/task/dart.dart
+++ b/pkg/analyzer/lib/src/task/dart.dart
@@ -223,6 +223,15 @@ final ResultDescriptor<bool> CREATED_RESOLVED_UNIT11 =
     new ResultDescriptor<bool>('CREATED_RESOLVED_UNIT11', false);
 
 /**
+ * The flag specifying that [RESOLVED_UNIT12] has been been computed for this
+ * compilation unit (without requiring that the AST for it still be in cache).
+ *
+ * The result is only available for [LibrarySpecificUnit]s.
+ */
+final ResultDescriptor<bool> CREATED_RESOLVED_UNIT12 =
+    new ResultDescriptor<bool>('CREATED_RESOLVED_UNIT12', false);
+
+/**
  * The flag specifying that [RESOLVED_UNIT2] has been been computed for this
  * compilation unit (without requiring that the AST for it still be in cache).
  *
@@ -642,8 +651,9 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT1 =
         cachingPolicy: AST_CACHING_POLICY);
 
 /**
- * The resolved [CompilationUnit] associated with a compilation unit, with
- * constants not yet resolved.
+ * The resolved [CompilationUnit] associated with a compilation unit in which
+ * the types of class members have been inferred in addition to everything that
+ * is true of a [RESOLVED_UNIT9].
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -653,7 +663,7 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT10 =
 
 /**
  * The resolved [CompilationUnit] associated with a compilation unit, with
- * constants resolved.
+ * constants not yet resolved.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -662,11 +672,20 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT11 =
         cachingPolicy: AST_CACHING_POLICY);
 
 /**
+ * The resolved [CompilationUnit] associated with a compilation unit, with
+ * constants resolved.
+ *
+ * The result is only available for [LibrarySpecificUnit]s.
+ */
+final ResultDescriptor<CompilationUnit> RESOLVED_UNIT12 =
+    new ResultDescriptor<CompilationUnit>('RESOLVED_UNIT12', null,
+        cachingPolicy: AST_CACHING_POLICY);
+
+/**
  * The partially resolved [CompilationUnit] associated with a compilation unit.
  *
- * Tasks that use this value as an input can assume that the [SimpleIdentifier]s
- * at all declaration sites have been bound to the element defined by the
- * declaration, including the constants defined in an 'enum' declaration.
+ * In addition to what is true of a [RESOLVED_UNIT1], tasks that use this value
+ * as an input can assume that its directives have been resolved.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -677,10 +696,9 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT2 =
 /**
  * The partially resolved [CompilationUnit] associated with a compilation unit.
  *
- * In addition to what is true of a [RESOLVED_UNIT2], tasks that use this value
- * as an input can assume that the types associated with declarations have been
- * resolved. This includes the types of superclasses, mixins, interfaces,
- * fields, return types, parameters, and local variables.
+ * Tasks that use this value as an input can assume that the [SimpleIdentifier]s
+ * at all declaration sites have been bound to the element defined by the
+ * declaration, including the constants defined in an 'enum' declaration.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -692,8 +710,9 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT3 =
  * The partially resolved [CompilationUnit] associated with a compilation unit.
  *
  * In addition to what is true of a [RESOLVED_UNIT3], tasks that use this value
- * as an input can assume that references to local variables and formal
- * parameters have been resolved.
+ * as an input can assume that the types associated with declarations have been
+ * resolved. This includes the types of superclasses, mixins, interfaces,
+ * fields, return types, parameters, and local variables.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -705,9 +724,8 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT4 =
  * The partially resolved [CompilationUnit] associated with a compilation unit.
  *
  * In addition to what is true of a [RESOLVED_UNIT4], tasks that use this value
- * as an input can assume that elements and types associated with expressions
- * outside of method bodies (essentially initializers) have been initially
- * resolved.
+ * as an input can assume that references to local variables and formal
+ * parameters have been resolved.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -719,8 +737,9 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT5 =
  * The partially resolved [CompilationUnit] associated with a compilation unit.
  *
  * In addition to what is true of a [RESOLVED_UNIT5], tasks that use this value
- * as an input can assume that the types of final variables have been
- * propagated.
+ * as an input can assume that elements and types associated with expressions
+ * outside of method bodies (essentially initializers) have been initially
+ * resolved.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -732,7 +751,8 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT6 =
  * The partially resolved [CompilationUnit] associated with a compilation unit.
  *
  * In addition to what is true of a [RESOLVED_UNIT6], tasks that use this value
- * as an input can assume that the types of static variables have been inferred.
+ * as an input can assume that the types of final variables have been
+ * propagated.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -744,8 +764,7 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT7 =
  * The partially resolved [CompilationUnit] associated with a compilation unit.
  *
  * In addition to what is true of a [RESOLVED_UNIT7], tasks that use this value
- * as an input can assume that the initializers of instance variables have been
- * re-resolved.
+ * as an input can assume that the types of static variables have been inferred.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -754,9 +773,11 @@ final ResultDescriptor<CompilationUnit> RESOLVED_UNIT8 =
         cachingPolicy: AST_CACHING_POLICY);
 
 /**
- * The resolved [CompilationUnit] associated with a compilation unit in which
- * the types of class members have been inferred in addition to everything that
- * is true of a [RESOLVED_UNIT8].
+ * The partially resolved [CompilationUnit] associated with a compilation unit.
+ *
+ * In addition to what is true of a [RESOLVED_UNIT8], tasks that use this value
+ * as an input can assume that the initializers of instance variables have been
+ * re-resolved.
  *
  * The result is only available for [LibrarySpecificUnit]s.
  */
@@ -1125,7 +1146,7 @@ class BuildEnumMemberElementsTask extends SourceBasedAnalysisTask {
       'BuildEnumMemberElementsTask',
       createTask,
       buildInputs,
-      <ResultDescriptor>[CREATED_RESOLVED_UNIT2, RESOLVED_UNIT2]);
+      <ResultDescriptor>[CREATED_RESOLVED_UNIT3, RESOLVED_UNIT3]);
 
   BuildEnumMemberElementsTask(
       InternalAnalysisContext context, AnalysisTarget target)
@@ -1160,8 +1181,8 @@ class BuildEnumMemberElementsTask extends SourceBasedAnalysisTask {
     //
     // Record outputs.
     //
-    outputs[CREATED_RESOLVED_UNIT2] = true;
-    outputs[RESOLVED_UNIT2] = unit;
+    outputs[CREATED_RESOLVED_UNIT3] = true;
+    outputs[RESOLVED_UNIT3] = unit;
   }
 
   /**
@@ -1173,7 +1194,7 @@ class BuildEnumMemberElementsTask extends SourceBasedAnalysisTask {
     LibrarySpecificUnit unit = target;
     return <String, TaskInput>{
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request),
-      UNIT_INPUT: RESOLVED_UNIT1.of(unit)
+      UNIT_INPUT: RESOLVED_UNIT2.of(unit)
     };
   }
 
@@ -1878,7 +1899,7 @@ class ComputeConstantValueTask extends ConstantEvaluationAnalysisTask {
 class ComputeInferableStaticVariableDependenciesTask
     extends InferStaticVariableTask {
   /**
-   * The name of the [RESOLVED_UNIT5] input.
+   * The name of the [RESOLVED_UNIT6] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -1932,7 +1953,7 @@ class ComputeInferableStaticVariableDependenciesTask
       CompilationUnitElementImpl unit = target
           .getAncestor((Element element) => element is CompilationUnitElement);
       return <String, TaskInput>{
-        UNIT_INPUT: RESOLVED_UNIT5
+        UNIT_INPUT: RESOLVED_UNIT6
             .of(new LibrarySpecificUnit(unit.librarySource, unit.source))
       };
     }
@@ -2062,7 +2083,7 @@ class ComputeLibraryCycleTask extends SourceBasedAnalysisTask {
 class ComputePropagableVariableDependenciesTask
     extends InferStaticVariableTask {
   /**
-   * The name of the [RESOLVED_UNIT5] input.
+   * The name of the [RESOLVED_UNIT6] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -2117,7 +2138,7 @@ class ComputePropagableVariableDependenciesTask
       CompilationUnitElementImpl unit = target
           .getAncestor((Element element) => element is CompilationUnitElement);
       return <String, TaskInput>{
-        UNIT_INPUT: RESOLVED_UNIT5
+        UNIT_INPUT: RESOLVED_UNIT6
             .of(new LibrarySpecificUnit(unit.librarySource, unit.source))
       };
     }
@@ -2483,11 +2504,11 @@ class DartErrorsTask extends SourceBasedAnalysisTask {
 }
 
 /**
- * A task that builds [RESOLVED_UNIT11] for a unit.
+ * A task that builds [RESOLVED_UNIT12] for a unit.
  */
 class EvaluateUnitConstantsTask extends SourceBasedAnalysisTask {
   /**
-   * The name of the [RESOLVED_UNIT10] input.
+   * The name of the [RESOLVED_UNIT11] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -2503,7 +2524,7 @@ class EvaluateUnitConstantsTask extends SourceBasedAnalysisTask {
       'EvaluateUnitConstantsTask',
       createTask,
       buildInputs,
-      <ResultDescriptor>[CREATED_RESOLVED_UNIT11, RESOLVED_UNIT11]);
+      <ResultDescriptor>[CREATED_RESOLVED_UNIT12, RESOLVED_UNIT12]);
 
   EvaluateUnitConstantsTask(AnalysisContext context, LibrarySpecificUnit target)
       : super(context, target);
@@ -2516,8 +2537,8 @@ class EvaluateUnitConstantsTask extends SourceBasedAnalysisTask {
     // No actual work needs to be performed; the task manager will ensure that
     // all constants are evaluated before this method is called.
     CompilationUnit unit = getRequiredInput(UNIT_INPUT);
-    outputs[RESOLVED_UNIT11] = unit;
-    outputs[CREATED_RESOLVED_UNIT11] = true;
+    outputs[RESOLVED_UNIT12] = unit;
+    outputs[CREATED_RESOLVED_UNIT12] = true;
   }
 
   /**
@@ -2529,7 +2550,7 @@ class EvaluateUnitConstantsTask extends SourceBasedAnalysisTask {
     LibrarySpecificUnit unit = target;
     return <String, TaskInput>{
       'libraryElement': LIBRARY_ELEMENT8.of(unit.library),
-      UNIT_INPUT: RESOLVED_UNIT10.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT11.of(unit),
       CONSTANT_VALUES:
           COMPILATION_UNIT_CONSTANTS.of(unit).toListOf(CONSTANT_VALUE),
       'constantExpressionsDependencies':
@@ -2552,7 +2573,7 @@ class EvaluateUnitConstantsTask extends SourceBasedAnalysisTask {
  */
 class GatherUsedImportedElementsTask extends SourceBasedAnalysisTask {
   /**
-   * The name of the [RESOLVED_UNIT10] input.
+   * The name of the [RESOLVED_UNIT11] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -2596,7 +2617,7 @@ class GatherUsedImportedElementsTask extends SourceBasedAnalysisTask {
    */
   static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
     LibrarySpecificUnit unit = target;
-    return <String, TaskInput>{UNIT_INPUT: RESOLVED_UNIT10.of(unit)};
+    return <String, TaskInput>{UNIT_INPUT: RESOLVED_UNIT11.of(unit)};
   }
 
   /**
@@ -2614,7 +2635,7 @@ class GatherUsedImportedElementsTask extends SourceBasedAnalysisTask {
  */
 class GatherUsedLocalElementsTask extends SourceBasedAnalysisTask {
   /**
-   * The name of the [RESOLVED_UNIT10] input.
+   * The name of the [RESOLVED_UNIT11] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -2658,7 +2679,7 @@ class GatherUsedLocalElementsTask extends SourceBasedAnalysisTask {
    */
   static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
     LibrarySpecificUnit unit = target;
-    return <String, TaskInput>{UNIT_INPUT: RESOLVED_UNIT10.of(unit)};
+    return <String, TaskInput>{UNIT_INPUT: RESOLVED_UNIT11.of(unit)};
   }
 
   /**
@@ -2676,7 +2697,7 @@ class GatherUsedLocalElementsTask extends SourceBasedAnalysisTask {
  */
 class GenerateHintsTask extends SourceBasedAnalysisTask {
   /**
-   * The name of the [RESOLVED_UNIT10] input.
+   * The name of the [RESOLVED_UNIT11] input.
    */
   static const String RESOLVED_UNIT_INPUT = 'RESOLVED_UNIT';
 
@@ -2895,7 +2916,7 @@ class InferInstanceMembersInUnitTask extends SourceBasedAnalysisTask {
   static const String TYPE_PROVIDER_INPUT = 'TYPE_PROVIDER_INPUT';
 
   /**
-   * The name of the input whose value is the [RESOLVED_UNIT7] for the
+   * The name of the input whose value is the [RESOLVED_UNIT8] for the
    * compilation unit.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
@@ -2907,7 +2928,7 @@ class InferInstanceMembersInUnitTask extends SourceBasedAnalysisTask {
       'InferInstanceMembersInUnitTask',
       createTask,
       buildInputs,
-      <ResultDescriptor>[CREATED_RESOLVED_UNIT9, RESOLVED_UNIT9]);
+      <ResultDescriptor>[CREATED_RESOLVED_UNIT10, RESOLVED_UNIT10]);
 
   /**
    * Initialize a newly created task to build a library element for the given
@@ -2939,8 +2960,8 @@ class InferInstanceMembersInUnitTask extends SourceBasedAnalysisTask {
     //
     // Record outputs.
     //
-    outputs[RESOLVED_UNIT9] = unit;
-    outputs[CREATED_RESOLVED_UNIT9] = true;
+    outputs[RESOLVED_UNIT10] = unit;
+    outputs[CREATED_RESOLVED_UNIT10] = true;
   }
 
   /**
@@ -2951,7 +2972,7 @@ class InferInstanceMembersInUnitTask extends SourceBasedAnalysisTask {
   static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
     LibrarySpecificUnit unit = target;
     return <String, TaskInput>{
-      UNIT_INPUT: RESOLVED_UNIT8.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT9.of(unit),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request),
       // In strong mode, add additional dependencies to enforce inference
       // ordering.
@@ -2959,14 +2980,14 @@ class InferInstanceMembersInUnitTask extends SourceBasedAnalysisTask {
       // Require that field re-resolution be complete for all units in the
       // current library cycle.
       'orderLibraryCycleTasks': LIBRARY_CYCLE_UNITS.of(unit).toList(
-          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT8.of(
+          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT9.of(
               new LibrarySpecificUnit(
                   (unit as CompilationUnitElementImpl).librarySource,
                   unit.source))),
       // Require that full inference be complete for all dependencies of the
       // current library cycle.
       'orderLibraryCycles': LIBRARY_CYCLE_DEPENDENCIES.of(unit).toList(
-          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT9.of(
+          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT10.of(
               new LibrarySpecificUnit(
                   (unit as CompilationUnitElementImpl).librarySource,
                   unit.source)))
@@ -3037,7 +3058,7 @@ abstract class InferStaticVariableTask extends ConstantEvaluationAnalysisTask {
  */
 class InferStaticVariableTypesInUnitTask extends SourceBasedAnalysisTask {
   /**
-   * The name of the input whose value is the [RESOLVED_UNIT6] for the
+   * The name of the input whose value is the [RESOLVED_UNIT7] for the
    * compilation unit.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
@@ -3055,7 +3076,7 @@ class InferStaticVariableTypesInUnitTask extends SourceBasedAnalysisTask {
       'InferStaticVariableTypesInUnitTask',
       createTask,
       buildInputs,
-      <ResultDescriptor>[CREATED_RESOLVED_UNIT7, RESOLVED_UNIT7]);
+      <ResultDescriptor>[CREATED_RESOLVED_UNIT8, RESOLVED_UNIT8]);
 
   /**
    * Initialize a newly created task to build a library element for the given
@@ -3079,8 +3100,8 @@ class InferStaticVariableTypesInUnitTask extends SourceBasedAnalysisTask {
     // because the work has implicitly been done by virtue of the task model
     // preparing all of the inputs.
     //
-    outputs[RESOLVED_UNIT7] = unit;
-    outputs[CREATED_RESOLVED_UNIT7] = true;
+    outputs[RESOLVED_UNIT8] = unit;
+    outputs[CREATED_RESOLVED_UNIT8] = true;
   }
 
   /**
@@ -3094,7 +3115,7 @@ class InferStaticVariableTypesInUnitTask extends SourceBasedAnalysisTask {
       INFERRED_VARIABLES_INPUT: INFERABLE_STATIC_VARIABLES_IN_UNIT
           .of(unit)
           .toListOf(INFERRED_STATIC_VARIABLE),
-      UNIT_INPUT: RESOLVED_UNIT6.of(unit)
+      UNIT_INPUT: RESOLVED_UNIT7.of(unit)
     };
   }
 
@@ -3125,7 +3146,7 @@ class InferStaticVariableTypeTask extends InferStaticVariableTask {
   static const String TYPE_PROVIDER_INPUT = 'TYPE_PROVIDER_INPUT';
 
   /**
-   * The name of the [RESOLVED_UNIT6] input.
+   * The name of the [RESOLVED_UNIT7] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -3216,14 +3237,14 @@ class InferStaticVariableTypeTask extends InferStaticVariableTask {
           .of(variable)
           .toListOf(INFERRED_STATIC_VARIABLE),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request),
-      UNIT_INPUT: RESOLVED_UNIT6.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT7.of(unit),
       // In strong mode, add additional dependencies to enforce inference
       // ordering.
 
       // Require that full inference be complete for all dependencies of the
       // current library cycle.
       'orderLibraryCycles': LIBRARY_CYCLE_DEPENDENCIES.of(unit).toList(
-          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT9.of(
+          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT10.of(
               new LibrarySpecificUnit(
                   (unit as CompilationUnitElementImpl).librarySource,
                   unit.source)))
@@ -3623,7 +3644,7 @@ class ParseDartTask extends SourceBasedAnalysisTask {
 }
 
 /**
- * A task that builds [RESOLVED_UNIT5] for a unit.
+ * A task that builds [RESOLVED_UNIT6] for a unit.
  */
 class PartiallyResolveUnitReferencesTask extends SourceBasedAnalysisTask {
   /**
@@ -3632,7 +3653,7 @@ class PartiallyResolveUnitReferencesTask extends SourceBasedAnalysisTask {
   static const String LIBRARY_INPUT = 'LIBRARY_INPUT';
 
   /**
-   * The name of the [RESOLVED_UNIT4] input.
+   * The name of the [RESOLVED_UNIT5] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -3650,8 +3671,8 @@ class PartiallyResolveUnitReferencesTask extends SourceBasedAnalysisTask {
       buildInputs, <ResultDescriptor>[
     INFERABLE_STATIC_VARIABLES_IN_UNIT,
     PROPAGABLE_VARIABLES_IN_UNIT,
-    CREATED_RESOLVED_UNIT5,
-    RESOLVED_UNIT5
+    CREATED_RESOLVED_UNIT6,
+    RESOLVED_UNIT6
   ]);
 
   PartiallyResolveUnitReferencesTask(
@@ -3685,8 +3706,8 @@ class PartiallyResolveUnitReferencesTask extends SourceBasedAnalysisTask {
       outputs[INFERABLE_STATIC_VARIABLES_IN_UNIT] = VariableElement.EMPTY_LIST;
     }
     outputs[PROPAGABLE_VARIABLES_IN_UNIT] = visitor.propagableVariables;
-    outputs[RESOLVED_UNIT5] = unit;
-    outputs[CREATED_RESOLVED_UNIT5] = true;
+    outputs[RESOLVED_UNIT6] = unit;
+    outputs[CREATED_RESOLVED_UNIT6] = true;
   }
 
   /**
@@ -3699,7 +3720,7 @@ class PartiallyResolveUnitReferencesTask extends SourceBasedAnalysisTask {
     return <String, TaskInput>{
       'fullyBuiltLibraryElements': READY_LIBRARY_ELEMENT5.of(unit.library),
       LIBRARY_INPUT: LIBRARY_ELEMENT5.of(unit.library),
-      UNIT_INPUT: RESOLVED_UNIT4.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT5.of(unit),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request),
       // In strong mode, add additional dependencies to enforce inference
       // ordering.
@@ -3707,7 +3728,7 @@ class PartiallyResolveUnitReferencesTask extends SourceBasedAnalysisTask {
       // Require that full inference be complete for all dependencies of the
       // current library cycle.
       'orderLibraryCycles': LIBRARY_CYCLE_DEPENDENCIES.of(unit).toList(
-          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT9.of(
+          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT10.of(
               new LibrarySpecificUnit(
                   (unit as CompilationUnitElementImpl).librarySource,
                   unit.source)))
@@ -3821,7 +3842,7 @@ class PropagateVariableTypesInLibraryTask extends SourceBasedAnalysisTask {
     Source source = target;
     return <String, TaskInput>{
       'propagatedVariableTypesInUnits':
-          LIBRARY_SPECIFIC_UNITS.of(source).toListOf(RESOLVED_UNIT6),
+          LIBRARY_SPECIFIC_UNITS.of(source).toListOf(RESOLVED_UNIT7),
       LIBRARY_INPUT: LIBRARY_ELEMENT5.of(source),
     };
   }
@@ -3842,7 +3863,7 @@ class PropagateVariableTypesInLibraryTask extends SourceBasedAnalysisTask {
  */
 class PropagateVariableTypesInUnitTask extends SourceBasedAnalysisTask {
   /**
-   * The name of the input whose value is the [RESOLVED_UNIT5] for the
+   * The name of the input whose value is the [RESOLVED_UNIT6] for the
    * compilation unit.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
@@ -3854,7 +3875,7 @@ class PropagateVariableTypesInUnitTask extends SourceBasedAnalysisTask {
       'PropagateVariableTypesInUnitTask',
       createTask,
       buildInputs,
-      <ResultDescriptor>[CREATED_RESOLVED_UNIT6, RESOLVED_UNIT6]);
+      <ResultDescriptor>[CREATED_RESOLVED_UNIT7, RESOLVED_UNIT7]);
 
   PropagateVariableTypesInUnitTask(
       InternalAnalysisContext context, LibrarySpecificUnit unit)
@@ -3874,8 +3895,8 @@ class PropagateVariableTypesInUnitTask extends SourceBasedAnalysisTask {
     // because the work has implicitly been done by virtue of the task model
     // preparing all of the inputs.
     //
-    outputs[RESOLVED_UNIT6] = unit;
-    outputs[CREATED_RESOLVED_UNIT6] = true;
+    outputs[RESOLVED_UNIT7] = unit;
+    outputs[CREATED_RESOLVED_UNIT7] = true;
   }
 
   /**
@@ -3888,7 +3909,7 @@ class PropagateVariableTypesInUnitTask extends SourceBasedAnalysisTask {
     return <String, TaskInput>{
       'variables':
           PROPAGABLE_VARIABLES_IN_UNIT.of(unit).toListOf(PROPAGATED_VARIABLE),
-      UNIT_INPUT: RESOLVED_UNIT5.of(unit)
+      UNIT_INPUT: RESOLVED_UNIT6.of(unit)
     };
   }
 
@@ -3913,7 +3934,7 @@ class PropagateVariableTypeTask extends InferStaticVariableTask {
   static const String TYPE_PROVIDER_INPUT = 'TYPE_PROVIDER_INPUT';
 
   /**
-   * The name of the [RESOLVED_UNIT5] input.
+   * The name of the [RESOLVED_UNIT6] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -3999,7 +4020,7 @@ class PropagateVariableTypeTask extends InferStaticVariableTask {
           .of(variable)
           .toListOf(PROPAGATED_VARIABLE),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request),
-      UNIT_INPUT: RESOLVED_UNIT5.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT6.of(unit),
     };
   }
 
@@ -4323,7 +4344,7 @@ class ResolveConstantExpressionTask extends ConstantEvaluationAnalysisTask {
           'Cannot build inputs for a ${target.runtimeType}');
     }
     return <String, TaskInput>{
-      'createdResolvedUnit': CREATED_RESOLVED_UNIT10
+      'createdResolvedUnit': CREATED_RESOLVED_UNIT11
           .of(new LibrarySpecificUnit(librarySource, target.source))
     };
   }
@@ -4339,6 +4360,80 @@ class ResolveConstantExpressionTask extends ConstantEvaluationAnalysisTask {
 }
 
 /**
+ * A task that resolves imports and export directives to already built elements.
+ */
+class ResolveDirectiveElementsTask extends SourceBasedAnalysisTask {
+  /**
+   * The name of the input whose value is the defining [LIBRARY_ELEMENT2].
+   */
+  static const String LIBRARY_INPUT = 'LIBRARY_INPUT';
+
+  /**
+   * The name of the input for [RESOLVED_UNIT1] of a unit.
+   */
+  static const String UNIT_INPUT = 'UNIT_INPUT';
+
+  /**
+   * The task descriptor describing this kind of task.
+   */
+  static final TaskDescriptor DESCRIPTOR = new TaskDescriptor(
+      'ResolveDirectiveElementsTask',
+      createTask,
+      buildInputs,
+      <ResultDescriptor>[CREATED_RESOLVED_UNIT2, RESOLVED_UNIT2]);
+
+  ResolveDirectiveElementsTask(
+      InternalAnalysisContext context, AnalysisTarget target)
+      : super(context, target);
+
+  @override
+  TaskDescriptor get descriptor => DESCRIPTOR;
+
+  @override
+  void internalPerform() {
+    LibrarySpecificUnit targetUnit = target;
+    //
+    // Prepare inputs.
+    //
+    CompilationUnit unit = getRequiredInput(UNIT_INPUT);
+    //
+    // Resolve directive AST nodes to elements.
+    //
+    if (targetUnit.unit == targetUnit.library) {
+      DirectiveResolver resolver = new DirectiveResolver();
+      unit.accept(resolver);
+    }
+    //
+    // Record outputs.
+    //
+    outputs[CREATED_RESOLVED_UNIT2] = true;
+    outputs[RESOLVED_UNIT2] = unit;
+  }
+
+  /**
+   * Return a map from the names of the inputs of this kind of task to the task
+   * input descriptors describing those inputs for a task with the
+   * given [target].
+   */
+  static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
+    LibrarySpecificUnit unit = target;
+    return <String, TaskInput>{
+      LIBRARY_INPUT: LIBRARY_ELEMENT2.of(unit.library),
+      UNIT_INPUT: RESOLVED_UNIT1.of(unit)
+    };
+  }
+
+  /**
+   * Create a [ResolveDirectiveElementsTask] based on the given [target] in
+   * the given [context].
+   */
+  static ResolveDirectiveElementsTask createTask(
+      AnalysisContext context, AnalysisTarget target) {
+    return new ResolveDirectiveElementsTask(context, target);
+  }
+}
+
+/**
  * A task that ensures that all of the inferable instance members in a
  * compilation unit have had their right hand sides re-resolved
  */
@@ -4354,7 +4449,7 @@ class ResolveInstanceFieldsInUnitTask extends SourceBasedAnalysisTask {
   static const String TYPE_PROVIDER_INPUT = 'TYPE_PROVIDER_INPUT';
 
   /**
-   * The name of the input whose value is the [RESOLVED_UNIT7] for the
+   * The name of the input whose value is the [RESOLVED_UNIT8] for the
    * compilation unit.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
@@ -4366,7 +4461,7 @@ class ResolveInstanceFieldsInUnitTask extends SourceBasedAnalysisTask {
       'ResolveInstanceFieldsInUnitTask',
       createTask,
       buildInputs,
-      <ResultDescriptor>[CREATED_RESOLVED_UNIT8, RESOLVED_UNIT8]);
+      <ResultDescriptor>[CREATED_RESOLVED_UNIT9, RESOLVED_UNIT9]);
 
   /**
    * Initialize a newly created task to build a library element for the given
@@ -4411,8 +4506,8 @@ class ResolveInstanceFieldsInUnitTask extends SourceBasedAnalysisTask {
     //
     // Record outputs.
     //
-    outputs[RESOLVED_UNIT8] = unit;
-    outputs[CREATED_RESOLVED_UNIT8] = true;
+    outputs[RESOLVED_UNIT9] = unit;
+    outputs[CREATED_RESOLVED_UNIT9] = true;
   }
 
   /**
@@ -4423,7 +4518,7 @@ class ResolveInstanceFieldsInUnitTask extends SourceBasedAnalysisTask {
   static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
     LibrarySpecificUnit unit = target;
     return <String, TaskInput>{
-      UNIT_INPUT: RESOLVED_UNIT7.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT8.of(unit),
       LIBRARY_INPUT: LIBRARY_ELEMENT5.of(unit.library),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request),
       // In strong mode, add additional dependencies to enforce inference
@@ -4432,14 +4527,14 @@ class ResolveInstanceFieldsInUnitTask extends SourceBasedAnalysisTask {
       // Require that static variable inference  be complete for all units in
       // the current library cycle.
       'orderLibraryCycleTasks': LIBRARY_CYCLE_UNITS.of(unit).toList(
-          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT7.of(
+          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT8.of(
               new LibrarySpecificUnit(
                   (unit as CompilationUnitElementImpl).librarySource,
                   unit.source))),
       // Require that full inference be complete for all dependencies of the
       // current library cycle.
       'orderLibraryCycles': LIBRARY_CYCLE_DEPENDENCIES.of(unit).toList(
-          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT9.of(
+          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT10.of(
               new LibrarySpecificUnit(
                   (unit as CompilationUnitElementImpl).librarySource,
                   unit.source)))
@@ -4457,7 +4552,7 @@ class ResolveInstanceFieldsInUnitTask extends SourceBasedAnalysisTask {
 }
 
 /**
- * A task that finishes resolution by requesting [RESOLVED_UNIT10] for every
+ * A task that finishes resolution by requesting [RESOLVED_UNIT11] for every
  * unit in the libraries closure and produces [LIBRARY_ELEMENT8].
  */
 class ResolveLibraryReferencesTask extends SourceBasedAnalysisTask {
@@ -4467,7 +4562,7 @@ class ResolveLibraryReferencesTask extends SourceBasedAnalysisTask {
   static const String LIBRARY_INPUT = 'LIBRARY_INPUT';
 
   /**
-   * The name of the list of [RESOLVED_UNIT10] input.
+   * The name of the list of [RESOLVED_UNIT11] input.
    */
   static const String UNITS_INPUT = 'UNITS_INPUT';
 
@@ -4515,7 +4610,7 @@ class ResolveLibraryReferencesTask extends SourceBasedAnalysisTask {
     Source source = target;
     return <String, TaskInput>{
       LIBRARY_INPUT: LIBRARY_ELEMENT7.of(source),
-      UNITS_INPUT: LIBRARY_SPECIFIC_UNITS.of(source).toListOf(RESOLVED_UNIT10),
+      UNITS_INPUT: LIBRARY_SPECIFIC_UNITS.of(source).toListOf(RESOLVED_UNIT11),
     };
   }
 
@@ -4530,7 +4625,7 @@ class ResolveLibraryReferencesTask extends SourceBasedAnalysisTask {
 }
 
 /**
- * A task that finishes resolution by requesting [RESOLVED_UNIT11] for every
+ * A task that finishes resolution by requesting [RESOLVED_UNIT12] for every
  * unit in the libraries closure and produces [LIBRARY_ELEMENT].
  */
 class ResolveLibraryTask extends SourceBasedAnalysisTask {
@@ -4540,7 +4635,7 @@ class ResolveLibraryTask extends SourceBasedAnalysisTask {
   static const String LIBRARY_INPUT = 'LIBRARY_INPUT';
 
   /**
-   * The name of the list of [RESOLVED_UNIT11] input.
+   * The name of the list of [RESOLVED_UNIT12] input.
    */
   static const String UNITS_INPUT = 'UNITS_INPUT';
 
@@ -4651,7 +4746,7 @@ class ResolveLibraryTypeNamesTask extends SourceBasedAnalysisTask {
     Source source = target;
     return <String, TaskInput>{
       'resolvedUnit':
-          LIBRARY_SPECIFIC_UNITS.of(source).toListOf(RESOLVED_UNIT3),
+          LIBRARY_SPECIFIC_UNITS.of(source).toListOf(RESOLVED_UNIT4),
       LIBRARY_INPUT: LIBRARY_ELEMENT4.of(source),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request)
     };
@@ -4683,7 +4778,7 @@ class ResolveUnitTask extends SourceBasedAnalysisTask {
   static const String TYPE_PROVIDER_INPUT = 'TYPE_PROVIDER_INPUT';
 
   /**
-   * The name of the [RESOLVED_UNIT9] input.
+   * The name of the [RESOLVED_UNIT10] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -4691,8 +4786,8 @@ class ResolveUnitTask extends SourceBasedAnalysisTask {
       'ResolveUnitTask', createTask, buildInputs, <ResultDescriptor>[
     CONSTANT_EXPRESSIONS_DEPENDENCIES,
     RESOLVE_UNIT_ERRORS,
-    CREATED_RESOLVED_UNIT10,
-    RESOLVED_UNIT10
+    CREATED_RESOLVED_UNIT11,
+    RESOLVED_UNIT11
   ]);
 
   ResolveUnitTask(
@@ -4738,8 +4833,8 @@ class ResolveUnitTask extends SourceBasedAnalysisTask {
     //
     outputs[CONSTANT_EXPRESSIONS_DEPENDENCIES] = constExprDependencies;
     outputs[RESOLVE_UNIT_ERRORS] = getTargetSourceErrors(errorListener, target);
-    outputs[RESOLVED_UNIT10] = unit;
-    outputs[CREATED_RESOLVED_UNIT10] = true;
+    outputs[RESOLVED_UNIT11] = unit;
+    outputs[CREATED_RESOLVED_UNIT11] = true;
   }
 
   /**
@@ -4752,14 +4847,14 @@ class ResolveUnitTask extends SourceBasedAnalysisTask {
     return <String, TaskInput>{
       LIBRARY_INPUT: LIBRARY_ELEMENT7.of(unit.library),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request),
-      UNIT_INPUT: RESOLVED_UNIT9.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT10.of(unit),
       // In strong mode, add additional dependencies to enforce inference
       // ordering.
 
       // Require that inference be complete for all units in the
       // current library cycle.
       'orderLibraryCycleTasks': LIBRARY_CYCLE_UNITS.of(unit).toList(
-          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT9.of(
+          (CompilationUnitElement unit) => CREATED_RESOLVED_UNIT10.of(
               new LibrarySpecificUnit(
                   (unit as CompilationUnitElementImpl).librarySource,
                   unit.source)))
@@ -4777,7 +4872,7 @@ class ResolveUnitTask extends SourceBasedAnalysisTask {
 }
 
 /**
- * A task that builds [RESOLVED_UNIT3] for a unit.
+ * A task that builds [RESOLVED_UNIT4] for a unit.
  */
 class ResolveUnitTypeNamesTask extends SourceBasedAnalysisTask {
   /**
@@ -4786,7 +4881,7 @@ class ResolveUnitTypeNamesTask extends SourceBasedAnalysisTask {
   static const String LIBRARY_INPUT = 'LIBRARY_INPUT';
 
   /**
-   * The name of the [RESOLVED_UNIT2] input.
+   * The name of the [RESOLVED_UNIT3] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -4801,8 +4896,8 @@ class ResolveUnitTypeNamesTask extends SourceBasedAnalysisTask {
   static final TaskDescriptor DESCRIPTOR = new TaskDescriptor(
       'ResolveUnitTypeNamesTask', createTask, buildInputs, <ResultDescriptor>[
     RESOLVE_TYPE_NAMES_ERRORS,
-    CREATED_RESOLVED_UNIT3,
-    RESOLVED_UNIT3
+    CREATED_RESOLVED_UNIT4,
+    RESOLVED_UNIT4
   ]);
 
   ResolveUnitTypeNamesTask(
@@ -4833,8 +4928,8 @@ class ResolveUnitTypeNamesTask extends SourceBasedAnalysisTask {
     //
     outputs[RESOLVE_TYPE_NAMES_ERRORS] =
         getTargetSourceErrors(errorListener, target);
-    outputs[RESOLVED_UNIT3] = unit;
-    outputs[CREATED_RESOLVED_UNIT3] = true;
+    outputs[RESOLVED_UNIT4] = unit;
+    outputs[CREATED_RESOLVED_UNIT4] = true;
   }
 
   /**
@@ -4851,7 +4946,7 @@ class ResolveUnitTypeNamesTask extends SourceBasedAnalysisTask {
       'importsExportNamespace':
           IMPORTED_LIBRARIES.of(unit.library).toMapOf(LIBRARY_ELEMENT4),
       LIBRARY_INPUT: LIBRARY_ELEMENT4.of(unit.library),
-      UNIT_INPUT: RESOLVED_UNIT2.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT3.of(unit),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request)
     };
   }
@@ -4867,7 +4962,7 @@ class ResolveUnitTypeNamesTask extends SourceBasedAnalysisTask {
 }
 
 /**
- * A task that builds [RESOLVED_UNIT4] for a unit.
+ * A task that builds [RESOLVED_UNIT5] for a unit.
  */
 class ResolveVariableReferencesTask extends SourceBasedAnalysisTask {
   /**
@@ -4876,7 +4971,7 @@ class ResolveVariableReferencesTask extends SourceBasedAnalysisTask {
   static const String LIBRARY_INPUT = 'LIBRARY_INPUT';
 
   /**
-   * The name of the [RESOLVED_UNIT3] input.
+   * The name of the [RESOLVED_UNIT4] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -4892,8 +4987,8 @@ class ResolveVariableReferencesTask extends SourceBasedAnalysisTask {
       'ResolveVariableReferencesTask',
       createTask,
       buildInputs, <ResultDescriptor>[
-    CREATED_RESOLVED_UNIT4,
-    RESOLVED_UNIT4,
+    CREATED_RESOLVED_UNIT5,
+    RESOLVED_UNIT5,
     VARIABLE_REFERENCE_ERRORS
   ]);
 
@@ -4925,8 +5020,8 @@ class ResolveVariableReferencesTask extends SourceBasedAnalysisTask {
     //
     // Record outputs.
     //
-    outputs[RESOLVED_UNIT4] = unit;
-    outputs[CREATED_RESOLVED_UNIT4] = true;
+    outputs[RESOLVED_UNIT5] = unit;
+    outputs[CREATED_RESOLVED_UNIT5] = true;
     outputs[VARIABLE_REFERENCE_ERRORS] =
         getTargetSourceErrors(errorListener, target);
   }
@@ -4940,7 +5035,7 @@ class ResolveVariableReferencesTask extends SourceBasedAnalysisTask {
     LibrarySpecificUnit unit = target;
     return <String, TaskInput>{
       LIBRARY_INPUT: LIBRARY_ELEMENT1.of(unit.library),
-      UNIT_INPUT: RESOLVED_UNIT3.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT4.of(unit),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request)
     };
   }
@@ -5092,7 +5187,7 @@ class ScanDartTask extends SourceBasedAnalysisTask {
  */
 class StrongModeVerifyUnitTask extends SourceBasedAnalysisTask {
   /**
-   * The name of the [RESOLVED_UNIT11] input.
+   * The name of the [RESOLVED_UNIT12] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
@@ -5148,7 +5243,7 @@ class StrongModeVerifyUnitTask extends SourceBasedAnalysisTask {
   static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
     LibrarySpecificUnit unit = target;
     return <String, TaskInput>{
-      UNIT_INPUT: RESOLVED_UNIT11.of(unit),
+      UNIT_INPUT: RESOLVED_UNIT12.of(unit),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request),
     };
   }