Update SOURCE_KIND when a missing source file appears

pkg/analyzer/lib/src/context/context.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 analyzer.src.context.context;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 999 matching lines @@
       Source source, String originalContents, String newContents, bool notify) {
     CacheEntry entry = _cache.get(source);
     if (entry == null) {
       return false;
     }
     bool changed = newContents != originalContents;
     if (newContents != null) {
       if (changed) {
         if (!analysisOptions.incremental ||
             !_tryPoorMansIncrementalResolution(source, newContents)) {
-          _sourceChanged(source);
+          // Don't compare with old contents because the cache has already been
+          // updated, and we know at this point that it changed.
+          _sourceChanged(source, compareWithOld: false);
         }
         entry.modificationTime = _contentCache.getModificationStamp(source);
         entry.setValue(CONTENT, newContents, TargetedResult.EMPTY_LIST);
       } else {
         entry.modificationTime = _contentCache.getModificationStamp(source);
       }
     } else if (originalContents != null) {
       // We are removing the overlay for the file, check if the file's
       // contents is the same as it was in the overlay.
       try {
@@ skipping 716 matching lines @@
     } else {
       entry.explicitlyAdded = true;
       entry.modificationTime = getModificationStamp(source);
       entry.setState(CONTENT, CacheState.INVALID);
     }
   }
 
   /**
    * Invalidate the [source] that was changed and any sources that referenced
    * the source before it existed.
+   *
+   * Note: source may be considered "changed" if it was previously missing,
+   * but pointed to by an import or export directive.
    */
-  void _sourceChanged(Source source) {
+  void _sourceChanged(Source source, {bool compareWithOld: true}) {
     CacheEntry entry = _cache.get(source);
-    // If the source is removed, we don't care about it.
+    // If the source has no cache entry, there is nothing to invalidate.
     if (entry == null) {
       return;
     }
-    // Check whether the content of the source is the same as it was the last
-    // time.
-    String sourceContent = entry.getValue(CONTENT);
-    if (sourceContent != null) {
-      entry.setState(CONTENT, CacheState.FLUSHED);
+
+    String oldContents = compareWithOld ? entry.getValue(CONTENT) : null;
+
+    // Flush so that from now on we will get new contents.
+    // (For example, in getLibrariesContaining.)
+    entry.setState(CONTENT, CacheState.FLUSHED);
+
+    if (oldContents != null) {
+      // Fast path if the content is the same as it was last time.
       try {
         TimestampedData<String> fileContents = getContents(source);
-        if (fileContents.data == sourceContent) {
+        if (fileContents.data == oldContents) {
           int time = fileContents.modificationTime;
           for (CacheEntry entry in _entriesFor(source)) {
             entry.modificationTime = time;
           }
           return;
         }
       } catch (e) {
         entry.modificationTime = -1;
       }
     }
@@ skipping 24 matching lines @@
 //              print(
 //                  'dartDelta: add=${dartDelta.addedNames} remove=${dartDelta.removedNames}');
               delta = dartDelta;
               entry.setState(CONTENT, CacheState.INVALID, delta: delta);
               return;
             }
           }
         }
       }
       entry.setState(CONTENT, CacheState.INVALID);
+      entry.setState(MODIFICATION_TIME, CacheState.INVALID);
+      entry.setState(SOURCE_KIND, CacheState.INVALID);
     }
     driver.reset();
     for (WorkManager workManager in workManagers) {
       workManager.applyChange(
           Source.EMPTY_LIST, <Source>[source], Source.EMPTY_LIST);
     }
   }
 
   /**
    * Record that the give [source] has been deleted.
@@ skipping 302 matching lines @@
     }
     DartSdk sdk = factory.dartSdk;
     if (sdk == null) {
       throw new IllegalArgumentException(
           "The source factory for an SDK analysis context must have a DartUriResolver");
     }
     return new AnalysisCache(
         <CachePartition>[AnalysisEngine.instance.partitionManager.forSdk(sdk)]);
   }
 }