diff --git a/src/lint/engine/ArcanistLintEngine.php b/src/lint/engine/ArcanistLintEngine.php
index ee80e6c2..f737fcd4 100644
--- a/src/lint/engine/ArcanistLintEngine.php
+++ b/src/lint/engine/ArcanistLintEngine.php
@@ -1,628 +1,618 @@
 <?php
 
 /**
  * Manages lint execution. When you run 'arc lint' or 'arc diff', Arcanist
  * attempts to run lint rules using a lint engine.
  *
  * Lint engines are high-level strategic classes which do not contain any
  * actual linting rules. Linting rules live in `Linter` classes. The lint
  * engine builds and configures linters.
  *
  * Most modern linters can be configured with an `.arclint` file, which is
  * managed by the builtin @{class:ArcanistConfigurationDrivenLintEngine}.
  * Consult the documentation for more information on these files.
  *
  * In the majority of cases, you do not need to write a custom lint engine.
  * For example, to add new rules for a new language, write a linter instead.
  * However, if you have a very advanced or specialized use case, you can write
  * a custom lint engine by extending this class; custom lint engines are more
  * powerful but much more complex than the builtin engines.
  *
  * The lint engine is given a list of paths (generally, the paths that you
  * modified in your change) and determines which linters to run on them. The
  * linters themselves are responsible for actually analyzing file text and
  * finding warnings and errors. For example, if the modified paths include some
  * JS files and some Python files, you might want to run JSLint on the JS files
  * and PyLint on the Python files.
  *
  * You can also run multiple linters on a single file. For instance, you might
  * run one linter on all text files to make sure they don't have trailing
  * whitespace, or enforce tab vs space rules, or make sure there are enough
  * curse words in them.
  *
  * You can test an engine like this:
  *
  *   arc lint --engine YourLintEngineClassName --lintall some_file.py
  *
  * ...which will show you all the lint issues raised in the file.
  *
  * See @{article@phabricator:Arcanist User Guide: Customizing Lint, Unit Tests
  * and Workflows} for more information about configuring lint engines.
  */
 abstract class ArcanistLintEngine extends Phobject {
 
   protected $workingCopy;
   protected $paths = array();
   protected $fileData = array();
 
   protected $charToLine = array();
   protected $lineToFirstChar = array();
   private $cachedResults;
   private $cacheVersion;
   private $repositoryVersion;
   private $results = array();
   private $stopped = array();
   private $minimumSeverity = ArcanistLintSeverity::SEVERITY_DISABLED;
 
   private $changedLines = array();
 
-  private $enableAsyncLint = false;
   private $configurationManager;
 
   private $linterResources = array();
 
   public function __construct() {}
 
   final public function setConfigurationManager(
     ArcanistConfigurationManager $configuration_manager) {
     $this->configurationManager = $configuration_manager;
     return $this;
   }
 
   final public function getConfigurationManager() {
     return $this->configurationManager;
   }
 
   final public function setWorkingCopy(
     ArcanistWorkingCopyIdentity $working_copy) {
     $this->workingCopy = $working_copy;
     return $this;
   }
 
   final public function getWorkingCopy() {
     return $this->workingCopy;
   }
 
   final public function setPaths($paths) {
     $this->paths = $paths;
     return $this;
   }
 
   public function getPaths() {
     return $this->paths;
   }
 
   final public function setPathChangedLines($path, $changed) {
     if ($changed === null) {
       $this->changedLines[$path] = null;
     } else {
       $this->changedLines[$path] = array_fill_keys($changed, true);
     }
     return $this;
   }
 
   final public function getPathChangedLines($path) {
     return idx($this->changedLines, $path);
   }
 
   final public function setFileData($data) {
     $this->fileData = $data + $this->fileData;
     return $this;
   }
 
-  final public function setEnableAsyncLint($enable_async_lint) {
-    $this->enableAsyncLint = $enable_async_lint;
-    return $this;
-  }
-
-  final public function getEnableAsyncLint() {
-    return $this->enableAsyncLint;
-  }
-
   final public function loadData($path) {
     if (!isset($this->fileData[$path])) {
       $disk_path = $this->getFilePathOnDisk($path);
       $this->fileData[$path] = Filesystem::readFile($disk_path);
     }
     return $this->fileData[$path];
   }
 
   public function pathExists($path) {
     $disk_path = $this->getFilePathOnDisk($path);
     return Filesystem::pathExists($disk_path);
   }
 
   final public function isDirectory($path) {
     $disk_path = $this->getFilePathOnDisk($path);
     return is_dir($disk_path);
   }
 
   final public function isBinaryFile($path) {
     try {
       $data = $this->loadData($path);
     } catch (Exception $ex) {
       return false;
     }
 
     return ArcanistDiffUtils::isHeuristicBinaryFile($data);
   }
 
   final public function isSymbolicLink($path) {
     return is_link($this->getFilePathOnDisk($path));
   }
 
   final public function getFilePathOnDisk($path) {
     return Filesystem::resolvePath(
       $path,
       $this->getWorkingCopy()->getProjectRoot());
   }
 
   final public function setMinimumSeverity($severity) {
     $this->minimumSeverity = $severity;
     return $this;
   }
 
   final public function run() {
     $linters = $this->buildLinters();
     if (!$linters) {
       throw new ArcanistNoEffectException(pht('No linters to run.'));
     }
 
     foreach ($linters as $key => $linter) {
       $linter->setLinterID($key);
     }
 
     $linters = msort($linters, 'getLinterPriority');
     foreach ($linters as $linter) {
       $linter->setEngine($this);
     }
 
     $have_paths = false;
     foreach ($linters as $linter) {
       if ($linter->getPaths()) {
         $have_paths = true;
         break;
       }
     }
 
     if (!$have_paths) {
       throw new ArcanistNoEffectException(pht('No paths are lintable.'));
     }
 
     $versions = array($this->getCacheVersion());
 
     foreach ($linters as $linter) {
       $version = get_class($linter).':'.$linter->getCacheVersion();
 
       $symbols = id(new PhutilSymbolLoader())
         ->setType('class')
         ->setName(get_class($linter))
         ->selectSymbolsWithoutLoading();
       $symbol = idx($symbols, 'class$'.get_class($linter));
       if ($symbol) {
         $version .= ':'.md5_file(
           phutil_get_library_root($symbol['library']).'/'.$symbol['where']);
       }
 
       $versions[] = $version;
     }
 
     $this->cacheVersion = crc32(implode("\n", $versions));
 
     $runnable = $this->getRunnableLinters($linters);
 
     $this->stopped = array();
 
     $exceptions = $this->executeLinters($runnable);
 
     foreach ($runnable as $linter) {
       foreach ($linter->getLintMessages() as $message) {
         $this->validateLintMessage($linter, $message);
 
         if (!$this->isSeverityEnabled($message->getSeverity())) {
           continue;
         }
         if (!$this->isRelevantMessage($message)) {
           continue;
         }
         $message->setGranularity($linter->getCacheGranularity());
         $result = $this->getResultForPath($message->getPath());
         $result->addMessage($message);
       }
     }
 
     if ($this->cachedResults) {
       foreach ($this->cachedResults as $path => $messages) {
         $messages = idx($messages, $this->cacheVersion, array());
         $repository_version = idx($messages, 'repository_version');
         unset($messages['stopped']);
         unset($messages['repository_version']);
         foreach ($messages as $message) {
           $use_cache = $this->shouldUseCache(
             idx($message, 'granularity'),
             $repository_version);
           if ($use_cache) {
             $this->getResultForPath($path)->addMessage(
               ArcanistLintMessage::newFromDictionary($message));
           }
         }
       }
     }
 
     foreach ($this->results as $path => $result) {
       $disk_path = $this->getFilePathOnDisk($path);
       $result->setFilePathOnDisk($disk_path);
       if (isset($this->fileData[$path])) {
         $result->setData($this->fileData[$path]);
       } else if ($disk_path && Filesystem::pathExists($disk_path)) {
         // TODO: this may cause us to, e.g., load a large binary when we only
         // raised an error about its filename. We could refine this by looking
         // through the lint messages and doing this load only if any of them
         // have original/replacement text or something like that.
         try {
           $this->fileData[$path] = Filesystem::readFile($disk_path);
           $result->setData($this->fileData[$path]);
         } catch (FilesystemException $ex) {
           // Ignore this, it's noncritical that we access this data and it
           // might be unreadable or a directory or whatever else for plenty
           // of legitimate reasons.
         }
       }
     }
 
     if ($exceptions) {
       throw new PhutilAggregateException(
         pht('Some linters failed:'),
         $exceptions);
     }
 
     return $this->results;
   }
 
   final public function isSeverityEnabled($severity) {
     $minimum = $this->minimumSeverity;
     return ArcanistLintSeverity::isAtLeastAsSevere($severity, $minimum);
   }
 
   final private function shouldUseCache(
     $cache_granularity,
     $repository_version) {
 
     switch ($cache_granularity) {
       case ArcanistLinter::GRANULARITY_FILE:
         return true;
       case ArcanistLinter::GRANULARITY_DIRECTORY:
       case ArcanistLinter::GRANULARITY_REPOSITORY:
         return ($this->repositoryVersion == $repository_version);
       default:
         return false;
     }
   }
 
   /**
    * @param dict<string path, dict<string version, list<dict message>>>
    * @return this
    */
   final public function setCachedResults(array $results) {
     $this->cachedResults = $results;
     return $this;
   }
 
   final public function getResults() {
     return $this->results;
   }
 
   final public function getStoppedPaths() {
     return $this->stopped;
   }
 
   abstract public function buildLinters();
 
   final public function setRepositoryVersion($version) {
     $this->repositoryVersion = $version;
     return $this;
   }
 
   final private function isRelevantMessage(ArcanistLintMessage $message) {
     // When a user runs "arc lint", we default to raising only warnings on
     // lines they have changed (errors are still raised anywhere in the
     // file). The list of $changed lines may be null, to indicate that the
     // path is a directory or a binary file so we should not exclude
     // warnings.
 
     if (!$this->changedLines ||
         $message->isError() ||
         $message->shouldBypassChangedLineFiltering()) {
       return true;
     }
 
     $locations = $message->getOtherLocations();
     $locations[] = $message->toDictionary();
 
     foreach ($locations as $location) {
       $path = idx($location, 'path', $message->getPath());
 
       if (!array_key_exists($path, $this->changedLines)) {
         if (phutil_is_windows()) {
           // We try checking the UNIX path form as well, on Windows.  Linters
           // store noramlized paths, which use the Windows-style "\" as a
           // delimiter; as such, they don't match the UNIX-style paths stored
           // in changedLines, which come from the VCS.
           $path = str_replace('\\', '/', $path);
           if (!array_key_exists($path, $this->changedLines)) {
             continue;
           }
         } else {
           continue;
         }
       }
 
       $changed = $this->getPathChangedLines($path);
 
       if ($changed === null || !$location['line']) {
         return true;
       }
 
       $last_line = $location['line'];
       if (isset($location['original'])) {
         $last_line += substr_count($location['original'], "\n");
       }
 
       for ($l = $location['line']; $l <= $last_line; $l++) {
         if (!empty($changed[$l])) {
           return true;
         }
       }
     }
 
     return false;
   }
 
   final protected function getResultForPath($path) {
     if (empty($this->results[$path])) {
       $result = new ArcanistLintResult();
       $result->setPath($path);
       $result->setCacheVersion($this->cacheVersion);
       $this->results[$path] = $result;
     }
     return $this->results[$path];
   }
 
   final public function getLineAndCharFromOffset($path, $offset) {
     if (!isset($this->charToLine[$path])) {
       $char_to_line = array();
       $line_to_first_char = array();
 
       $lines = explode("\n", $this->loadData($path));
       $line_number = 0;
       $line_start = 0;
       foreach ($lines as $line) {
         $len = strlen($line) + 1; // Account for "\n".
         $line_to_first_char[] = $line_start;
         $line_start += $len;
         for ($ii = 0; $ii < $len; $ii++) {
           $char_to_line[] = $line_number;
         }
         $line_number++;
       }
       $this->charToLine[$path] = $char_to_line;
       $this->lineToFirstChar[$path] = $line_to_first_char;
     }
 
     $line = $this->charToLine[$path][$offset];
     $char = $offset - $this->lineToFirstChar[$path][$line];
 
     return array($line, $char);
   }
 
   protected function getCacheVersion() {
     return 1;
   }
 
 
   /**
    * Get a named linter resource shared by another linter.
    *
    * This mechanism allows linters to share arbitrary resources, like the
    * results of computation. If several linters need to perform the same
    * expensive computation step, they can use a named resource to synchronize
    * construction of the result so it doesn't need to be built multiple
    * times.
    *
    * @param string  Resource identifier.
    * @param wild    Optionally, default value to return if resource does not
    *                exist.
    * @return wild   Resource, or default value if not present.
    */
   public function getLinterResource($key, $default = null) {
     return idx($this->linterResources, $key, $default);
   }
 
 
   /**
    * Set a linter resource that other linters can access.
    *
    * See @{method:getLinterResource} for a description of this mechanism.
    *
    * @param string Resource identifier.
    * @param wild   Resource.
    * @return this
    */
   public function setLinterResource($key, $value) {
     $this->linterResources[$key] = $value;
     return $this;
   }
 
 
   private function getRunnableLinters(array $linters) {
     assert_instances_of($linters, 'ArcanistLinter');
 
     // TODO: The canRun() mechanism is only used by one linter, and just
     // silently disables the linter. Almost every other linter handles this
     // by throwing `ArcanistMissingLinterException`. Both mechanisms are not
     // ideal; linters which can not run should emit a message, get marked as
     // "skipped", and allow execution to continue. See T7045.
 
     $runnable = array();
     foreach ($linters as $key => $linter) {
       if ($linter->canRun()) {
         $runnable[$key] = $linter;
       }
     }
 
     return $runnable;
   }
 
   private function executeLinters(array $runnable) {
     assert_instances_of($runnable, 'ArcanistLinter');
 
     $all_paths = $this->getPaths();
     $path_chunks = array_chunk($all_paths, 32, $preserve_keys = true);
 
     $exception_lists = array();
     foreach ($path_chunks as $chunk) {
       $exception_lists[] = $this->executeLintersOnChunk($runnable, $chunk);
     }
 
     return array_mergev($exception_lists);
   }
 
 
   private function executeLintersOnChunk(array $runnable, array $path_list) {
     assert_instances_of($runnable, 'ArcanistLinter');
 
     $path_map = array_fuse($path_list);
 
     $exceptions = array();
     $did_lint = array();
     foreach ($runnable as $linter) {
       $linter_id = $linter->getLinterID();
       $paths = $linter->getPaths();
 
       foreach ($paths as $key => $path) {
         // If we aren't running this path in the current chunk of paths,
         // skip it completely.
         if (empty($path_map[$path])) {
           unset($paths[$key]);
           continue;
         }
 
         // Make sure each path has a result generated, even if it is empty
         // (i.e., the file has no lint messages).
         $result = $this->getResultForPath($path);
 
         // If a linter has stopped all other linters for this path, don't
         // actually run the linter.
         if (isset($this->stopped[$path])) {
           unset($paths[$key]);
           continue;
         }
 
         // If we have a cached result for this path, don't actually run the
         // linter.
         if (isset($this->cachedResults[$path][$this->cacheVersion])) {
           $cached_result = $this->cachedResults[$path][$this->cacheVersion];
 
           $use_cache = $this->shouldUseCache(
             $linter->getCacheGranularity(),
             idx($cached_result, 'repository_version'));
 
           if ($use_cache) {
             unset($paths[$key]);
             if (idx($cached_result, 'stopped') == $linter_id) {
               $this->stopped[$path] = $linter_id;
             }
           }
         }
       }
 
       $paths = array_values($paths);
 
       if (!$paths) {
         continue;
       }
 
       try {
         $this->executeLinterOnPaths($linter, $paths);
         $did_lint[] = array($linter, $paths);
       } catch (Exception $ex) {
         $exceptions[] = $ex;
       }
     }
 
     foreach ($did_lint as $info) {
       list($linter, $paths) = $info;
       try {
         $this->executeDidLintOnPaths($linter, $paths);
       } catch (Exception $ex) {
         $exceptions[] = $ex;
       }
     }
 
     return $exceptions;
   }
 
   private function beginLintServiceCall(ArcanistLinter $linter, array $paths) {
     $profiler = PhutilServiceProfiler::getInstance();
 
     return $profiler->beginServiceCall(
       array(
         'type' => 'lint',
         'linter' => $linter->getInfoName(),
         'paths' => $paths,
       ));
   }
 
   private function endLintServiceCall($call_id) {
     $profiler = PhutilServiceProfiler::getInstance();
     $profiler->endServiceCall($call_id, array());
   }
 
   private function executeLinterOnPaths(ArcanistLinter $linter, array $paths) {
     $call_id = $this->beginLintServiceCall($linter, $paths);
 
     try {
       $linter->willLintPaths($paths);
       foreach ($paths as $path) {
         $linter->setActivePath($path);
         $linter->lintPath($path);
         if ($linter->didStopAllLinters()) {
           $this->stopped[$path] = $linter->getLinterID();
         }
       }
     } catch (Exception $ex) {
       $this->endLintServiceCall($call_id);
       throw $ex;
     }
 
     $this->endLintServiceCall($call_id);
   }
 
   private function executeDidLintOnPaths(ArcanistLinter $linter, array $paths) {
     $call_id = $this->beginLintServiceCall($linter, $paths);
 
     try {
       $linter->didLintPaths($paths);
     } catch (Exception $ex) {
       $this->endLintServiceCall($call_id);
       throw $ex;
     }
 
     $this->endLintServiceCall($call_id);
   }
 
   private function validateLintMessage(
     ArcanistLinter $linter,
     ArcanistLintMessage $message) {
 
     $name = $message->getName();
     if (!strlen($name)) {
       throw new Exception(
         pht(
           'Linter "%s" generated a lint message that is invalid because it '.
           'does not have a name. Lint messages must have a name.',
           get_class($linter)));
     }
   }
 
 }
diff --git a/src/workflow/ArcanistLintWorkflow.php b/src/workflow/ArcanistLintWorkflow.php
index de215aad..249ffc82 100644
--- a/src/workflow/ArcanistLintWorkflow.php
+++ b/src/workflow/ArcanistLintWorkflow.php
@@ -1,662 +1,655 @@
 <?php
 
 /**
  * Runs lint rules on changes.
  */
 final class ArcanistLintWorkflow extends ArcanistWorkflow {
 
   const RESULT_OKAY       = 0;
   const RESULT_WARNINGS   = 1;
   const RESULT_ERRORS     = 2;
   const RESULT_SKIP       = 3;
 
   const DEFAULT_SEVERITY = ArcanistLintSeverity::SEVERITY_ADVICE;
 
   private $unresolvedMessages;
   private $shouldLintAll;
   private $shouldAmendChanges = false;
   private $shouldAmendWithoutPrompt = false;
   private $shouldAmendAutofixesWithoutPrompt = false;
   private $engine;
 
   public function getWorkflowName() {
     return 'lint';
   }
 
   public function setShouldAmendChanges($should_amend) {
     $this->shouldAmendChanges = $should_amend;
     return $this;
   }
 
   public function setShouldAmendWithoutPrompt($should_amend) {
     $this->shouldAmendWithoutPrompt = $should_amend;
     return $this;
   }
 
   public function setShouldAmendAutofixesWithoutPrompt($should_amend) {
     $this->shouldAmendAutofixesWithoutPrompt = $should_amend;
     return $this;
   }
 
   public function getCommandSynopses() {
     return phutil_console_format(<<<EOTEXT
       **lint** [__options__] [__paths__]
       **lint** [__options__] --rev [__rev__]
 EOTEXT
       );
   }
 
   public function getCommandHelp() {
     return phutil_console_format(<<<EOTEXT
           Supports: git, svn, hg
           Run static analysis on changes to check for mistakes. If no files
           are specified, lint will be run on all files which have been modified.
 EOTEXT
       );
   }
 
   public function getArguments() {
     return array(
       'lintall' => array(
         'help' => pht(
           'Show all lint warnings, not just those on changed lines. When '.
           'paths are specified, this is the default behavior.'),
         'conflicts' => array(
           'only-changed' => true,
         ),
       ),
       'only-changed' => array(
         'help' => pht(
           'Show lint warnings just on changed lines. When no paths are '.
           'specified, this is the default. This differs from only-new '.
           'in cases where line modifications introduce lint on other '.
           'unmodified lines.'),
         'conflicts' => array(
           'lintall' => true,
         ),
       ),
       'rev' => array(
         'param' => 'revision',
         'help' => pht('Lint changes since a specific revision.'),
         'supports' => array(
           'git',
           'hg',
         ),
         'nosupport' => array(
           'svn' => pht('Lint does not currently support %s in SVN.', '--rev'),
         ),
       ),
       'output' => array(
         'param' => 'format',
         'help' => pht(
           "With 'summary', show lint warnings in a more compact format. ".
           "With 'json', show lint warnings in machine-readable JSON format. ".
           "With 'none', show no lint warnings. ".
           "With 'compiler', show lint warnings in suitable for your editor. ".
           "With 'xml', show lint warnings in the Checkstyle XML format."),
       ),
       'outfile' => array(
         'param' => 'path',
         'help' => pht(
           'Output the linter results to a file. Defaults to stdout.'),
       ),
       'only-new' => array(
         'param' => 'bool',
         'supports' => array('git', 'hg'), // TODO: svn
         'help' => pht(
           'Display only messages not present in the original code.'),
       ),
       'engine' => array(
         'param' => 'classname',
         'help' => pht('Override configured lint engine for this project.'),
       ),
       'apply-patches' => array(
         'help' => pht(
           'Apply patches suggested by lint to the working copy without '.
           'prompting.'),
         'conflicts' => array(
           'never-apply-patches' => true,
         ),
       ),
       'never-apply-patches' => array(
         'help' => pht('Never apply patches suggested by lint.'),
         'conflicts' => array(
           'apply-patches' => true,
         ),
       ),
       'amend-all' => array(
         'help' => pht(
           'When linting git repositories, amend HEAD with all patches '.
           'suggested by lint without prompting.'),
       ),
       'amend-autofixes' => array(
         'help' => pht(
           'When linting git repositories, amend HEAD with autofix '.
           'patches suggested by lint without prompting.'),
       ),
       'everything' => array(
         'help' => pht('Lint all files in the project.'),
         'conflicts' => array(
           'cache' => pht('%s lints all files', '--everything'),
           'rev' => pht('%s lints all files', '--everything'),
         ),
       ),
       'severity' => array(
         'param' => 'string',
         'help' => pht(
           "Set minimum message severity. One of: %s. Defaults to '%s'.",
           sprintf(
             "'%s'",
             implode(
               "', '",
               array_keys(ArcanistLintSeverity::getLintSeverities()))),
           self::DEFAULT_SEVERITY),
       ),
       'cache' => array(
         'param' => 'bool',
         'help' => pht(
           "%d to disable cache, %d to enable. The default value is determined ".
           "by '%s' in configuration, which defaults to off. See notes in '%s'.",
           0,
           1,
           'arc.lint.cache',
           'arc.lint.cache'),
       ),
       '*' => 'paths',
     );
   }
 
   public function requiresAuthentication() {
     return (bool)$this->getArgument('only-new');
   }
 
   public function requiresWorkingCopy() {
     return true;
   }
 
   public function requiresRepositoryAPI() {
     return true;
   }
 
   private function getCacheKey() {
     return implode("\n", array(
       get_class($this->engine),
       $this->getArgument('severity', self::DEFAULT_SEVERITY),
       $this->shouldLintAll,
     ));
   }
 
   public function run() {
     $console = PhutilConsole::getConsole();
     $working_copy = $this->getWorkingCopy();
     $configuration_manager = $this->getConfigurationManager();
 
     $engine = $this->newLintEngine($this->getArgument('engine'));
 
     $rev = $this->getArgument('rev');
     $paths = $this->getArgument('paths');
     $use_cache = $this->getArgument('cache', null);
     $everything = $this->getArgument('everything');
     if ($everything && $paths) {
       throw new ArcanistUsageException(
         pht(
           'You can not specify paths with %s. The %s flag lints every file.',
           '--everything',
           '--everything'));
     }
     if ($use_cache === null) {
       $use_cache = (bool)$configuration_manager->getConfigFromAnySource(
         'arc.lint.cache',
         false);
     }
 
     if ($rev && $paths) {
       throw new ArcanistUsageException(
         pht('Specify either %s or paths.', '--rev'));
     }
 
 
     // NOTE: When the user specifies paths, we imply --lintall and show all
     // warnings for the paths in question. This is easier to deal with for
     // us and less confusing for users.
     $this->shouldLintAll = $paths ? true : false;
     if ($this->getArgument('lintall')) {
       $this->shouldLintAll = true;
     } else if ($this->getArgument('only-changed')) {
       $this->shouldLintAll = false;
     }
 
     if ($everything) {
       $paths = iterator_to_array($this->getRepositoryAPI()->getAllFiles());
       $this->shouldLintAll = true;
     } else {
       $paths = $this->selectPathsForWorkflow($paths, $rev);
     }
 
     $this->engine = $engine;
 
     $engine->setMinimumSeverity(
       $this->getArgument('severity', self::DEFAULT_SEVERITY));
 
     $file_hashes = array();
     if ($use_cache) {
       $engine->setRepositoryVersion($this->getRepositoryVersion());
       $cache = $this->readScratchJSONFile('lint-cache.json');
       $cache = idx($cache, $this->getCacheKey(), array());
       $cached = array();
 
       foreach ($paths as $path) {
         $abs_path = $engine->getFilePathOnDisk($path);
         if (!Filesystem::pathExists($abs_path)) {
           continue;
         }
         $file_hashes[$abs_path] = md5_file($abs_path);
 
         if (!isset($cache[$path])) {
           continue;
         }
         $messages = idx($cache[$path], $file_hashes[$abs_path]);
         if ($messages !== null) {
           $cached[$path] = $messages;
         }
       }
 
       if ($cached) {
         $console->writeErr(
           "%s\n",
           pht(
             "Using lint cache, use '%s' to disable it.",
             '--cache 0'));
       }
 
       $engine->setCachedResults($cached);
     }
 
     // Propagate information about which lines changed to the lint engine.
     // This is used so that the lint engine can drop warning messages
     // concerning lines that weren't in the change.
     $engine->setPaths($paths);
     if (!$this->shouldLintAll) {
       foreach ($paths as $path) {
         // Note that getChangedLines() returns null to indicate that a file
         // is binary or a directory (i.e., changed lines are not relevant).
         $engine->setPathChangedLines(
           $path,
           $this->getChangedLines($path, 'new'));
       }
     }
 
-    // Enable possible async linting only for 'arc diff' not 'arc lint'
-    if ($this->getParentWorkflow()) {
-      $engine->setEnableAsyncLint(true);
-    } else {
-      $engine->setEnableAsyncLint(false);
-    }
-
     if ($this->getArgument('only-new')) {
       $conduit = $this->getConduit();
       $api = $this->getRepositoryAPI();
       if ($rev) {
         $api->setBaseCommit($rev);
       }
       $svn_root = id(new PhutilURI($api->getSourceControlPath()))->getPath();
 
       $all_paths = array();
       foreach ($paths as $path) {
         $path = str_replace(DIRECTORY_SEPARATOR, '/', $path);
         $full_paths = array($path);
 
         $change = $this->getChange($path);
         $type = $change->getType();
         if (ArcanistDiffChangeType::isOldLocationChangeType($type)) {
           $full_paths = $change->getAwayPaths();
         } else if (ArcanistDiffChangeType::isNewLocationChangeType($type)) {
           continue;
         } else if (ArcanistDiffChangeType::isDeleteChangeType($type)) {
           continue;
         }
 
         foreach ($full_paths as $full_path) {
           $all_paths[$svn_root.'/'.$full_path] = $path;
         }
       }
 
       $lint_future = $conduit->callMethod('diffusion.getlintmessages', array(
         'repositoryPHID' => idx($this->loadProjectRepository(), 'phid'),
         'branch' => '', // TODO: Tracking branch.
         'commit' => $api->getBaseCommit(),
         'files' => array_keys($all_paths),
       ));
     }
 
     $failed = null;
     try {
       $engine->run();
     } catch (Exception $ex) {
       $failed = $ex;
     }
 
     $results = $engine->getResults();
 
     if ($this->getArgument('only-new')) {
       $total = 0;
       foreach ($results as $result) {
         $total += count($result->getMessages());
       }
 
       // Don't wait for response with default value of --only-new.
       $timeout = null;
       if ($this->getArgument('only-new') === null || !$total) {
         $timeout = 0;
       }
 
       $raw_messages = $this->resolveCall($lint_future, $timeout);
       if ($raw_messages && $total) {
         $old_messages = array();
         $line_maps = array();
         foreach ($raw_messages as $message) {
           $path = $all_paths[$message['path']];
           $line = $message['line'];
           $code = $message['code'];
 
           if (!isset($line_maps[$path])) {
             $line_maps[$path] = $this->getChange($path)->buildLineMap();
           }
 
           $new_lines = idx($line_maps[$path], $line);
           if (!$new_lines) { // Unmodified lines after last hunk.
             $last_old = ($line_maps[$path] ? last_key($line_maps[$path]) : 0);
             $news = array_filter($line_maps[$path]);
             $last_new = ($news ? last(end($news)) : 0);
             $new_lines = array($line + $last_new - $last_old);
           }
 
           $error = array($code => array(true));
           foreach ($new_lines as $new) {
             if (isset($old_messages[$path][$new])) {
               $old_messages[$path][$new][$code][] = true;
               break;
             }
             $old_messages[$path][$new] = &$error;
           }
           unset($error);
         }
 
         foreach ($results as $result) {
           foreach ($result->getMessages() as $message) {
             $path = str_replace(DIRECTORY_SEPARATOR, '/', $message->getPath());
             $line = $message->getLine();
             $code = $message->getCode();
             if (!empty($old_messages[$path][$line][$code])) {
               $message->setObsolete(true);
               array_pop($old_messages[$path][$line][$code]);
             }
           }
           $result->sortAndFilterMessages();
         }
       }
     }
 
     if ($this->getArgument('never-apply-patches')) {
       $apply_patches = false;
     } else {
       $apply_patches = true;
     }
 
     if ($this->getArgument('apply-patches')) {
       $prompt_patches = false;
     } else {
       $prompt_patches = true;
     }
 
     if ($this->getArgument('amend-all')) {
       $this->shouldAmendChanges = true;
       $this->shouldAmendWithoutPrompt = true;
     }
 
     if ($this->getArgument('amend-autofixes')) {
       $prompt_autofix_patches = false;
       $this->shouldAmendChanges = true;
       $this->shouldAmendAutofixesWithoutPrompt = true;
     } else {
       $prompt_autofix_patches = true;
     }
 
     $repository_api = $this->getRepositoryAPI();
     if ($this->shouldAmendChanges) {
       $this->shouldAmendChanges = $repository_api->supportsAmend() &&
         !$this->isHistoryImmutable();
     }
 
     $wrote_to_disk = false;
 
     switch ($this->getArgument('output')) {
       case 'json':
         $renderer = new ArcanistJSONLintRenderer();
         $prompt_patches = false;
         $apply_patches = $this->getArgument('apply-patches');
         break;
       case 'summary':
         $renderer = new ArcanistSummaryLintRenderer();
         break;
       case 'none':
         $prompt_patches = false;
         $apply_patches = $this->getArgument('apply-patches');
         $renderer = new ArcanistNoneLintRenderer();
         break;
       case 'compiler':
         $renderer = new ArcanistCompilerLintRenderer();
         $prompt_patches = false;
         $apply_patches = $this->getArgument('apply-patches');
         break;
       case 'xml':
         $renderer = new ArcanistCheckstyleXMLLintRenderer();
         $prompt_patches = false;
         $apply_patches = $this->getArgument('apply-patches');
         break;
       default:
         $renderer = new ArcanistConsoleLintRenderer();
         $renderer->setShowAutofixPatches($prompt_autofix_patches);
         break;
     }
 
     $all_autofix = true;
     $tmp = null;
 
     if ($this->getArgument('outfile') !== null) {
       $tmp = id(new TempFile())
         ->setPreserveFile(true);
     }
 
     $preamble = $renderer->renderPreamble();
     if ($tmp) {
       Filesystem::appendFile($tmp, $preamble);
     } else {
       $console->writeOut('%s', $preamble);
     }
 
     foreach ($results as $result) {
       $result_all_autofix = $result->isAllAutofix();
 
       if (!$result->getMessages() && !$result_all_autofix) {
         continue;
       }
 
       if (!$result_all_autofix) {
         $all_autofix = false;
       }
 
       $lint_result = $renderer->renderLintResult($result);
       if ($lint_result) {
         if ($tmp) {
           Filesystem::appendFile($tmp, $lint_result);
         } else {
           $console->writeOut('%s', $lint_result);
         }
       }
 
       if ($apply_patches && $result->isPatchable()) {
         $patcher = ArcanistLintPatcher::newFromArcanistLintResult($result);
         $old_file = $result->getFilePathOnDisk();
 
         if ($prompt_patches &&
             !($result_all_autofix && !$prompt_autofix_patches)) {
           if (!Filesystem::pathExists($old_file)) {
             $old_file = '/dev/null';
           }
           $new_file = new TempFile();
           $new = $patcher->getModifiedFileContent();
           Filesystem::writeFile($new_file, $new);
 
           // TODO: Improve the behavior here, make it more like
           // difference_render().
           list(, $stdout, $stderr) =
             exec_manual('diff -u %s %s', $old_file, $new_file);
           $console->writeOut('%s', $stdout);
           $console->writeErr('%s', $stderr);
 
           $prompt = pht(
             'Apply this patch to %s?',
             phutil_console_format('__%s__', $result->getPath()));
           if (!phutil_console_confirm($prompt, $default_no = false)) {
             continue;
           }
         }
 
         $patcher->writePatchToDisk();
         $wrote_to_disk = true;
         $file_hashes[$old_file] = md5_file($old_file);
       }
     }
 
     $postamble = $renderer->renderPostamble();
     if ($tmp) {
       Filesystem::appendFile($tmp, $postamble);
       Filesystem::rename($tmp, $this->getArgument('outfile'));
     } else {
       $console->writeOut('%s', $postamble);
     }
 
     if ($wrote_to_disk && $this->shouldAmendChanges) {
       if ($this->shouldAmendWithoutPrompt ||
           ($this->shouldAmendAutofixesWithoutPrompt && $all_autofix)) {
         $console->writeOut(
           "<bg:yellow>** %s **</bg> %s\n",
           pht('LINT NOTICE'),
           pht('Automatically amending HEAD with lint patches.'));
         $amend = true;
       } else {
         $amend = phutil_console_confirm(pht('Amend HEAD with lint patches?'));
       }
 
       if ($amend) {
         if ($repository_api instanceof ArcanistGitAPI) {
           // Add the changes to the index before amending
           $repository_api->execxLocal('add -u');
         }
 
         $repository_api->amendCommit();
       } else {
         throw new ArcanistUsageException(
           pht(
             'Sort out the lint changes that were applied to the working '.
             'copy and relint.'));
       }
     }
 
     if ($this->getArgument('output') == 'json') {
       // NOTE: Required by save_lint.php in Phabricator.
       return 0;
     }
 
     if ($failed) {
       if ($failed instanceof ArcanistNoEffectException) {
         if ($renderer instanceof ArcanistNoneLintRenderer) {
           return 0;
         }
       }
       throw $failed;
     }
 
     $unresolved = array();
     $has_warnings = false;
     $has_errors = false;
 
     foreach ($results as $result) {
       foreach ($result->getMessages() as $message) {
         if (!$message->isPatchApplied()) {
           if ($message->isError()) {
             $has_errors = true;
           } else if ($message->isWarning()) {
             $has_warnings = true;
           }
           $unresolved[] = $message;
         }
       }
     }
     $this->unresolvedMessages = $unresolved;
 
     $cache = $this->readScratchJSONFile('lint-cache.json');
     $cached = idx($cache, $this->getCacheKey(), array());
     if ($cached || $use_cache) {
       $stopped = $engine->getStoppedPaths();
       foreach ($results as $result) {
         $path = $result->getPath();
         if (!$use_cache) {
           unset($cached[$path]);
           continue;
         }
         $abs_path = $engine->getFilePathOnDisk($path);
         if (!Filesystem::pathExists($abs_path)) {
           continue;
         }
         $version = $result->getCacheVersion();
         $cached_path = array();
         if (isset($stopped[$path])) {
           $cached_path['stopped'] = $stopped[$path];
         }
         $cached_path['repository_version'] = $this->getRepositoryVersion();
         foreach ($result->getMessages() as $message) {
           $granularity = $message->getGranularity();
           if ($granularity == ArcanistLinter::GRANULARITY_GLOBAL) {
             continue;
           }
           if (!$message->isPatchApplied()) {
             $cached_path[] = $message->toDictionary();
           }
         }
         $hash = idx($file_hashes, $abs_path);
         if (!$hash) {
           $hash = md5_file($abs_path);
         }
         $cached[$path] = array($hash => array($version => $cached_path));
       }
       $cache[$this->getCacheKey()] = $cached;
       // TODO: Garbage collection.
       $this->writeScratchJSONFile('lint-cache.json', $cache);
     }
 
     // Take the most severe lint message severity and use that
     // as the result code.
     if ($has_errors) {
       $result_code = self::RESULT_ERRORS;
     } else if ($has_warnings) {
       $result_code = self::RESULT_WARNINGS;
     } else {
       $result_code = self::RESULT_OKAY;
     }
 
     if (!$this->getParentWorkflow()) {
       if ($result_code == self::RESULT_OKAY) {
         $console->writeOut('%s', $renderer->renderOkayResult());
       }
     }
 
     return $result_code;
   }
 
   public function getUnresolvedMessages() {
     return $this->unresolvedMessages;
   }
 
 }