Prioritize analysis of files that import the changed file, or have an error or warning.

pkg/analyzer/lib/src/dart/analysis/file_tracker.dart

Index: pkg/analyzer/lib/src/dart/analysis/file_tracker.dart
diff --git a/pkg/analyzer/lib/src/dart/analysis/file_tracker.dart b/pkg/analyzer/lib/src/dart/analysis/file_tracker.dart
index aa34c330ee5e599ed87680bd815bb182a2cc67e1..3419cb4fe3c5d8f1f92e20e7cd89c8e0ec10cf51 100644
--- a/pkg/analyzer/lib/src/dart/analysis/file_tracker.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/file_tracker.dart
@@ -61,7 +61,7 @@ class FileTracker {
   /**
    * The set of files that are currently scheduled for analysis.
    */
-  final _pendingFiles = new LinkedHashSet<String>();
+  var _pendingFiles = new LinkedHashSet<String>();
 
   FileTracker(
       this.logger,
@@ -172,7 +172,39 @@ class FileTracker {
       if (anyApiChanged) {
         logger.writeln('API signatures mismatch found for $path');
         // TODO(scheglov) schedule analysis of only affected files
-        _pendingFiles.addAll(addedFiles);
+        var pendingFiles = new LinkedHashSet<String>();
+
+        // Add the changed file.
+        if (addedFiles.contains(path)) {
+          pendingFiles.add(path);
+        }
+
+        // Add files that directly import the changed file.
+        for (String addedPath in addedFiles) {
+          FileState addedFile = fsState.getFileForPath(addedPath);
+          for (FileState changedFile in files) {
+            if (addedFile.importedFiles.contains(changedFile)) {
+              pendingFiles.add(addedPath);
+            }
+          }
+        }
+
+        // Add files with errors or warnings that might be fixed.
+        for (String addedPath in addedFiles) {
+          FileState addedFile = fsState.getFileForPath(addedPath);
+          if (addedFile.hasErrorOrWarning) {
+            pendingFiles.add(addedPath);
+          }
+        }
+
+        // Add all previous pending files.
+        pendingFiles.addAll(_pendingFiles);

[Brian Wilkerson, 2017/04/10 18:17:38]

Are we sure we want to add previous pending files after indirect files? If they
were explicitly changed it seems like they should be analyzed before files that
*might* be effected by changes.

[scheglov, 2017/04/10 18:51:58]

Well, we would need a way to distinguish which files in existing pending queue
were added there because the were changed, from the files that were added
because they might be affected to a previously changed file. Probably we would
need two separate buckets - for pending changed files, and all other pending
files (imports, errors, the rest). I don't know if it is worth.

+
+        // Add all the rest.
+        pendingFiles.addAll(addedFiles);
+
+        // Replace pending files.
+        _pendingFiles = pendingFiles;
       }
       return files[0];
     });