diff --git a/scripts/phutil_rebuild_map.php b/scripts/phutil_rebuild_map.php
index bd9a6621..865f30dc 100755
--- a/scripts/phutil_rebuild_map.php
+++ b/scripts/phutil_rebuild_map.php
@@ -1,578 +1,588 @@
 #!/usr/bin/env php
 <?php
 
 /*
  * Copyright 2012 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 require_once dirname(__FILE__).'/__init_script__.php';
 
 $args = new PhutilArgumentParser($argv);
 $args->setTagline('rebuild the library map file');
 $args->setSynopsis(<<<EOHELP
     **phutil_rebuild_map.php** [__options__] __root__
         Rebuild the library map file for a libphutil library.
 
 EOHELP
 );
 
 $args->parseStandardArguments();
 $args->parse(
   array(
     array(
       'name'      => 'quiet',
       'help'      => 'Do not write status messages to stderr.',
     ),
     array(
       'name'      => 'drop-cache',
       'help'      => 'Drop the symbol cache and rebuild the entire map from '.
                      'scratch.',
     ),
     array(
       'name'      => 'limit',
       'param'     => 'N',
       'default'   => 8,
       'help'      => 'Controls the number of symbol mapper subprocesses run '.
                      'at once. Defaults to 8.',
     ),
     array(
       'name'      => 'show',
       'help'      => 'Print symbol map to stdout instead of writing it to the '.
                      'map file.',
     ),
     array(
       'name'      => 'ugly',
       'help'      => 'Use faster but less readable serialization for --show.',
     ),
     array(
       'name'      => 'root',
       'wildcard'  => true,
     )
   ));
 
 $root = $args->getArg('root');
 if (count($root) !== 1) {
   throw new Exception("Provide exactly one library root!");
 }
 $root = Filesystem::resolvePath(head($root));
 
 $builder = new PhutilLibraryMapBuilder($root);
 
 $builder->setQuiet($args->getArg('quiet'));
 $builder->setSubprocessLimit($args->getArg('limit'));
 
 if ($args->getArg('drop-cache')) {
   $builder->dropSymbolCache();
 }
 
 if ($args->getArg('show')) {
   $builder->setShowMap(true);
   $builder->setUgly($args->getArg('ugly'));
 }
 
 $builder->buildMap();
 
 exit(0);
 
 
 
 
 /**
  * Build maps of libphutil libraries. libphutil uses the library map to locate
  * and load classes and functions in the library.
  *
  * @task map      Mapping libphutil Libraries
  * @task path     Path Management
  * @task symbol   Symbol Analysis and Caching
  * @task source   Source Management
  */
 final class PhutilLibraryMapBuilder {
 
   private $root;
   private $quiet;
   private $subprocessLimit = 8;
   private $ugly;
   private $showMap;
 
   const LIBRARY_MAP_VERSION_KEY   = '__library_version__';
   const LIBRARY_MAP_VERSION       = 2;
 
   const SYMBOL_CACHE_VERSION_KEY  = '__symbol_cache_version__';
   const SYMBOL_CACHE_VERSION      = 2;
 
 
 /* -(  Mapping libphutil Libraries  )---------------------------------------- */
 
 
   /**
    * Create a new map builder for a library.
    *
    * @param string Path to the library root.
    *
    * @task map
    */
   public function __construct($root) {
     $this->root = $root;
   }
 
 
   /**
    * Control status output. Use --quiet to set this.
    *
    * @param   bool  If true, don't show status output.
    * @return  this
    *
    * @task map
    */
   public function setQuiet($quiet) {
     $this->quiet = $quiet;
     return $this;
   }
 
 
   /**
    * Control subprocess parallelism limit. Use --limit to set this.
    *
    * @param   int   Maximum number of subprocesses to run in parallel.
    * @return  this
    *
    * @task map
    */
   public function setSubprocessLimit($limit) {
     $this->subprocessLimit = $limit;
     return $this;
   }
 
 
   /**
    * Control whether the ugly (but fast) or pretty (but slower) JSON formatter
    * is used.
    *
    * @param   bool  If true, use the fastest formatter.
    * @return  this
    *
    * @task map
    */
   public function setUgly($ugly) {
     $this->ugly = $ugly;
     return $this;
   }
 
 
   /**
    * Control whether the map should be rebuilt, or just shown (printed to
    * stdout in JSON).
    *
    * @param bool  If true, show map instead of updating.
    * @return this
    *
    * @task map
    */
   public function setShowMap($show_map) {
     $this->showMap = $show_map;
     return $this;
   }
 
 
   /**
    * Build or rebuild the library map.
    *
    * @return this
    *
    * @task map
    */
   public function buildMap() {
 
     // Identify all the ".php" source files in the library.
     $this->log("Finding source files...\n");
     $source_map = $this->loadSourceFileMap();
     $this->log("Found ".number_format(count($source_map))." files.\n");
 
 
     // Load the symbol cache with existing parsed symbols. This allows us
     // to remap libraries quickly by analyzing only changed files.
     $this->log("Loading symbol cache...\n");
     $symbol_cache = $this->loadSymbolCache();
 
 
     // Build out the symbol analysis for all the files in the library. For
     // each file, check if it's in cache. If we miss in the cache, do a fresh
     // analysis.
     $symbol_map = array();
     $futures = array();
     foreach ($source_map as $file => $hash) {
       if (!empty($symbol_cache[$hash])) {
         $symbol_map[$file] = $symbol_cache[$hash];
         continue;
       }
       $futures[$file] = $this->buildSymbolAnalysisFuture($file);
     }
     $this->log("Found ".number_format(count($symbol_map))." files in cache.\n");
 
 
     // Run the analyzer on any files which need analysis.
     if ($futures) {
       $limit = $this->subprocessLimit;
       $count = number_format(count($futures));
 
       $this->log("Analyzing {$count} files with {$limit} subprocesses...\n");
 
       foreach (Futures($futures)->limit($limit) as $file => $future) {
+        $result = $future->resolveJSON();
+        if (empty($result['error'])) {
+          $symbol_map[$file] = $result;
+        } else {
+          echo phutil_console_format(
+            "\n**SYNTAX ERROR!**\nFile: %s\nLine: %d\n\n%s\n",
+            Filesystem::readablePath($result['file']),
+            $result['line'],
+            $result['error']);
+          exit(1);
+        }
         $this->log(".");
-        $symbol_map[$file] = $future->resolveJSON();
       }
       $this->log("\nDone.\n");
     }
 
 
     // We're done building the cache, so write it out immediately. Note that
     // we've only retained entries for files we found, so this implicitly cleans
     // out old cache entries.
     $this->writeSymbolCache($symbol_map, $source_map);
 
 
     // Our map is up to date, so either show it on stdout or write it to disk.
 
     if ($this->showMap) {
       $this->log("Showing map...\n");
 
       if ($this->ugly) {
         echo json_encode($symbol_map);
       } else {
         $json = new PhutilJSON();
         echo $json->encodeFormatted($symbol_map);
       }
     } else {
       $this->log("Building library map...\n");
       $library_map = $this->buildLibraryMap($symbol_map, $source_map);
 
       $this->log("Writing map...\n");
       $this->writeLibraryMap($library_map);
     }
 
     $this->log("Done.\n");
 
     return $this;
   }
 
 
   /**
    * Write a status message to the user, if not running in quiet mode.
    *
    * @param   string Message to write.
    * @return  this
    *
    * @task map
    */
   private function log($message) {
     if (!$this->quiet) {
       @fwrite(STDERR, $message);
     }
     return $this;
   }
 
 
 /* -(  Path Management  )---------------------------------------------------- */
 
 
   /**
    * Get the path to some file in the library.
    *
    * @param string  A library-relative path. If omitted, returns the library
    *                root path.
    * @return string An absolute path.
    *
    * @task path
    */
   private function getPath($path = '') {
     return $this->root.'/'.$path;
   }
 
 
   /**
    * Get the path to the symbol cache file.
    *
    * @return string Absolute path to symbol cache.
    *
    * @task path
    */
   private function getPathForSymbolCache() {
     return $this->getPath('.phutil_module_cache');
   }
 
 
   /**
    * Get the path to the map file.
    *
    * @return string Absolute path to the library map.
    *
    * @task path
    */
   private function getPathForLibraryMap() {
     return $this->getPath('__phutil_library_map__.php');
   }
 
 
   /**
    * Get the path to the library init file.
    *
    * @return string Absolute path to the library init file
    *
    * @task path
    */
   private function getPathForLibraryInit() {
     return $this->getPath('__phutil_library_init__.php');
   }
 
 
 /* -(  Symbol Analysis and Caching  )---------------------------------------- */
 
 
   /**
    * Load the library symbol cache, if it exists and is readable and valid.
    *
    * @return  dict  Map of content hashes to cache of output from
    *                `phutil_symbols.php`.
    *
    * @task symbol
    */
   private function loadSymbolCache() {
     $cache_file = $this->getPathForSymbolCache();
 
     try {
       $cache = Filesystem::readFile($cache_file);
     } catch (Exception $ex) {
       $cache = null;
     }
 
     $symbol_cache = array();
     if ($cache) {
       $symbol_cache = json_decode($cache, true);
       if (!is_array($symbol_cache)) {
         $symbol_cache = array();
       }
     }
 
     $version = idx($symbol_cache, self::SYMBOL_CACHE_VERSION_KEY);
     if ($version != self::SYMBOL_CACHE_VERSION) {
       // Throw away caches from a different version of the library.
       $symbol_cache = array();
     }
     unset($symbol_cache[self::SYMBOL_CACHE_VERSION_KEY]);
 
     return $symbol_cache;
   }
 
 
   /**
    * Write a symbol map to disk cache.
    *
    * @param dict  Symbol map of relative paths to symbols.
    * @param dict  Source map (like @{method:loadSourceFileMap}).
    * @return void
    *
    * @task symbol
    */
   private function writeSymbolCache(array $symbol_map, array $source_map) {
     $cache_file = $this->getPathForSymbolCache();
 
     $cache = array(
       self::SYMBOL_CACHE_VERSION_KEY => self::SYMBOL_CACHE_VERSION,
     );
 
     foreach ($symbol_map as $file => $symbols) {
       $cache[$source_map[$file]] = $symbols;
     }
 
     $json = json_encode($cache);
     Filesystem::writeFile($cache_file, $json);
   }
 
 
   /**
    * Drop the symbol cache, forcing a clean rebuild.
    *
    * @return this
    *
    * @task symbol
    */
   public function dropSymbolCache() {
     $this->log("Dropping symbol cache...\n");
     Filesystem::remove($this->getPathForSymbolCache());
   }
 
 
   /**
    * Build a future which returns a `phutil_symbols.php` analysis of a source
    * file.
    *
    * @param   string  Relative path to the source file to analyze.
    * @return  Future  Analysis future.
    *
    * @task symbol
    */
   private function buildSymbolAnalysisFuture($file) {
     $absolute_file = $this->getPath($file);
     $bin = dirname(__FILE__).'/phutil_symbols.php';
 
     return new ExecFuture('%s --ugly -- %s', $bin, $absolute_file);
   }
 
 
 /* -(  Source Management  )-------------------------------------------------- */
 
 
   /**
    * Build a map of all source files in a library to hashes of their content.
    * Returns an array like this:
    *
    *   array(
    *     'src/parser/ExampleParser.php' => '60b725f10c9c85c70d97880dfe8191b3',
    *     // ...
    *   );
    *
    * @return  dict    Map of library-relative paths to content hashes.
    * @task source
    */
   private function loadSourceFileMap() {
     $root = $this->getPath();
 
     $init = $this->getPathForLibraryInit();
     if (!Filesystem::pathExists($init)) {
       throw new Exception("Provided path '{$root}' is not a phutil library.");
     }
 
     $files = id(new FileFinder($root))
       ->withType('f')
       ->withSuffix('php')
       ->excludePath('*/.*')
       ->setGenerateChecksums(true)
       ->find();
 
     $map = array();
     foreach ($files as $file => $hash) {
       if (basename($file) == '__init__.php') {
         // TODO: Remove this once we kill __init__.php. This just makes the
         // script run faster until we do, so testing and development is less
         // annoying.
         continue;
       }
 
       $file = Filesystem::readablePath($file, $root);
       $file = ltrim($file, '/');
 
       if (dirname($file) == '.') {
         // We don't permit normal source files at the root level, so just ignore
         // them; they're special library files.
         continue;
       }
 
       $map[$file] = $hash;
     }
 
     return $map;
   }
 
 
   /**
    * Convert the symbol analysis of all the source files in the library into
    * a library map.
    *
    * @param   dict  Symbol analysis of all source files.
    * @return  dict  Library map.
    * @task source
    */
   private function buildLibraryMap(array $symbol_map) {
     $library_map = array(
       'class'     => array(),
       'function'  => array(),
       'xmap'      => array(),
     );
 
     // Detect duplicate symbols within the library.
     foreach ($symbol_map as $file => $info) {
       foreach ($info['have'] as $type => $symbols) {
         foreach ($symbols as $symbol => $declaration) {
           $lib_type = ($type == 'interface') ? 'class' : $type;
           if (!empty($library_map[$lib_type][$symbol])) {
             $prior = $library_map[$lib_type][$symbol];
             throw new Exception(
               "Definition of {$type} '{$symbol}' in file '{$file}' duplicates ".
               "prior definition in file '{$prior}'. You can not declare the ".
               "same symbol twice.");
           }
           $library_map[$lib_type][$symbol] = $file;
         }
       }
       $library_map['xmap'] += $info['xmap'];
     }
 
     // Simplify the common case (one parent) to make the file a little easier
     // to deal with.
     foreach ($library_map['xmap'] as $class => $extends) {
       if (count($extends) == 1) {
         $library_map['xmap'][$class] = reset($extends);
       }
     }
 
     // Sort the map so it is relatively stable across changes.
     foreach ($library_map as $key => $symbols) {
       ksort($symbols);
       $library_map[$key] = $symbols;
     }
     ksort($library_map);
 
     return $library_map;
   }
 
 
   /**
    * Write a finalized library map.
    *
    * @param  dict Library map structure to write.
    * @return void
    *
    * @task source
    */
   private function writeLibraryMap(array $library_map) {
     $map_file = $this->getPathForLibraryMap();
     $version = self::LIBRARY_MAP_VERSION;
 
     $library_map = array(
       self::LIBRARY_MAP_VERSION_KEY => $version,
     ) + $library_map;
 
     $library_map = var_export($library_map, $return_string = true);
     $library_map = preg_replace('/\s+$/m', '', $library_map);
     $library_map = preg_replace('/array \(/', 'array(', $library_map);
     $at = '@';
 
     $source_file = <<<EOPHP
 <?php
 
 /**
  * This file is automatically generated. Use 'arc liberate' to rebuild it.
  * {$at}generated
  * {$at}phutil-library-version {$version}
  */
 
 phutil_register_library_map({$library_map});
 
 EOPHP;
 
     Filesystem::writeFile($map_file, $source_file);
   }
 
 }
diff --git a/scripts/phutil_symbols.php b/scripts/phutil_symbols.php
index 8e1b2229..28253596 100755
--- a/scripts/phutil_symbols.php
+++ b/scripts/phutil_symbols.php
@@ -1,429 +1,442 @@
 #!/usr/bin/env php
 <?php
 
 /*
  * Copyright 2012 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 // We have to do this first before we load any symbols, because we define the
 // builtin symbol list through introspection.
 $builtins = phutil_symbols_get_builtins();
 
 require_once dirname(__FILE__).'/__init_script__.php';
 
 $args = new PhutilArgumentParser($argv);
 $args->setTagline('identify symbols in a PHP source file');
 $args->setSynopsis(<<<EOHELP
     **phutil_symbols.php** [__options__] __path.php__
         Identify the symbols (clases, functions and interfaces) in a PHP
         source file. Symbols are divided into "have" symbols (symbols the file
         declares) and "need" symbols (symbols the file depends on). For example,
         class declarations are "have" symbols, while object instantiations
         with "new X()" are "need" symbols.
 
         Dependencies on builtins and symbols marked '@phutil-external-symbol'
         in docblocks are omitted without __--all__.
 
         Symbols are reported in JSON on stdout.
 
         This script is used internally by libphutil/arcanist to build maps of
         library symbols.
 
         It would be nice to eventually implement this as a C++ xhpast binary,
         as it's relatively stable and performance is currently awful
         (500ms+ for moderately large files).
 
 EOHELP
 );
 $args->parseStandardArguments();
 $args->parse(
   array(
     array(
       'name'      => 'all',
       'help'      => 'Report all symbols, including builtins and declared '.
                      'externals.',
     ),
     array(
       'name'      => 'ugly',
       'help'      => 'Do not prettify JSON output.',
     ),
     array(
       'name'      => 'path',
       'wildcard'  => true,
       'help'      => 'PHP Source file to analyze.',
     ),
   ));
 
 $paths = $args->getArg('path');
 if (count($paths) !== 1) {
   throw new Exception("Specify exactly one path!");
 }
 $path = Filesystem::resolvePath(head($paths));
 
 $show_all = $args->getArg('all');
 
 $source_code = Filesystem::readFile($path);
-$tree = XHPASTTree::newFromData($source_code);
+
+try {
+  $tree = XHPASTTree::newFromData($source_code);
+} catch (XHPASTSyntaxErrorException $ex) {
+  $result = array(
+    'error' => $ex->getMessage(),
+    'line'  => $ex->getErrorLine(),
+    'file'  => $path,
+  );
+  $json = new PhutilJSON();
+  echo $json->encodeFormatted($result);
+  exit(0);
+}
+
 $root = $tree->getRootNode();
 
 $root->buildSelectCache();
 
 
 // -(  Marked Externals  )------------------------------------------------------
 
 
 // Identify symbols marked with "@phutil-external-symbol", so we exclude them
 // from the dependency list.
 
 $externals = array();
 $doc_parser = new PhutilDocblockParser();
 foreach ($root->getTokens() as $token) {
   if ($token->getTypeName() == 'T_DOC_COMMENT') {
     list($block, $special) = $doc_parser->parse($token->getValue());
 
     $ext_list = idx($special, 'phutil-external-symbol');
     $ext_list = explode("\n", $ext_list);
     $ext_list = array_filter($ext_list);
 
     foreach ($ext_list as $ext_ref) {
       $matches = null;
       if (preg_match('/^\s*(\S+)\s+(\S+)/', $ext_ref, $matches)) {
         $externals[$matches[1]][$matches[2]] = true;
       }
     }
   }
 }
 
 
 // -(  Declarations and Dependencies  )-----------------------------------------
 
 
 // The first stage of analysis is to find all the symbols we declare in the
 // file (like functions and classes) and all the symbols we use in the file
 // (like calling functions and invoking classes). Later, we filter this list
 // to exclude builtins.
 
 
 $have = array();  // For symbols we declare.
 $need = array();  // For symbols we use.
 $xmap = array();  // For extended classes and implemented interfaces.
 
 
 // -(  Functions  )-------------------------------------------------------------
 
 
 // Find functions declared in this file.
 
 // This is "function f() { ... }".
 $functions = $root->selectDescendantsOfType('n_FUNCTION_DECLARATION');
 foreach ($functions as $function) {
   $name = $function->getChildByIndex(2);
   if ($name->getTypeName() == 'n_EMPTY') {
     // This is an anonymous function; don't record it into the symbol
     // index.
     continue;
   }
   $have[] = array(
     'type'    => 'function',
     'symbol'  => $name,
   );
 }
 
 
 // Find functions used by this file. Uses:
 //
 //   - Explicit Call
 //   - String literal passed to call_user_func() or call_user_func_array()
 //
 // TODO: Possibly support these:
 //
 //   - String literal in ReflectionFunction().
 
 // This is "f();".
 $calls = $root->selectDescendantsOfType('n_FUNCTION_CALL');
 foreach ($calls as $call) {
   $name = $call->getChildByIndex(0);
   if ($name->getTypeName() == 'n_VARIABLE' ||
       $name->getTypeName() == 'n_VARIABLE_VARIABLE') {
     // Ignore these, we can't analyze them.
     continue;
   }
   if ($name->getTypeName() == 'n_CLASS_STATIC_ACCESS') {
     // These are "C::f()", we'll pick this up later on.
     continue;
   }
   $call_name = $name->getConcreteString();
   if ($call_name == 'call_user_func' ||
       $call_name == 'call_user_func_array') {
     $params = $call->getChildByIndex(1)->getChildren();
     if (!count($params)) {
       // This is a bare call_user_func() with no arguments; just ignore it.
       continue;
     }
     $symbol = array_shift($params);
     $symbol_value = $symbol->getStringLiteralValue();
     if ($symbol_value) {
       $need[] = array(
         'type'    => 'function',
         'name'    => $symbol_value,
         'symbol'  => $symbol,
       );
     }
   } else {
     $need[] = array(
       'type'    => 'function',
       'symbol'  => $name,
     );
   }
 }
 
 
 // -(  Classes  )---------------------------------------------------------------
 
 
 // Find classes declared by this file.
 
 
 // This is "class X ... { ... }".
 $classes = $root->selectDescendantsOfType('n_CLASS_DECLARATION');
 foreach ($classes as $class) {
   $class_name = $class->getChildByIndex(1);
   $have[] = array(
     'type'    => 'class',
     'symbol'  => $class_name,
   );
 }
 
 
 // Find classes used by this file. We identify these:
 //
 //  - class ... extends X
 //  - new X
 //  - Static method call
 //  - Static property access
 //  - Use of class constant
 //
 // TODO: Possibly support these:
 //
 //  - typehints
 //  - instanceof
 //  - catch
 //  - String literal in ReflectionClass().
 //  - String literal in array literal in call_user_func()/call_user_func_array()
 
 
 // This is "class X ... { ... }".
 $classes = $root->selectDescendantsOfType('n_CLASS_DECLARATION');
 foreach ($classes as $class) {
   $class_name = $class->getChildByIndex(1)->getConcreteString();
   $extends = $class->getChildByIndex(2);
   foreach ($extends->selectDescendantsOfType('n_CLASS_NAME') as $parent) {
     $need[] = array(
       'type'    => 'class',
       'symbol'  => $parent,
     );
 
     // Track all 'extends' in the extension map.
     $xmap[$class_name][] = $parent->getConcreteString();
   }
 }
 
 // This is "new X()".
 $uses_of_new = $root->selectDescendantsOfType('n_NEW');
 foreach ($uses_of_new as $new_operator) {
   $name = $new_operator->getChildByIndex(0);
   if ($name->getTypeName() == 'n_VARIABLE' ||
       $name->getTypeName() == 'n_VARIABLE_VARIABLE') {
     continue;
   }
   $need[] = array(
     'type'    => 'class',
     'symbol'  => $name,
   );
 }
 
 // This covers all of "X::$y", "X::y()" and "X::CONST".
 $static_uses = $root->selectDescendantsOfType('n_CLASS_STATIC_ACCESS');
 foreach ($static_uses as $static_use) {
   $name = $static_use->getChildByIndex(0);
   if ($name->getTypeName() != 'n_CLASS_NAME') {
     continue;
   }
   $name_concrete = $name->getConcreteString();
   $magic_names = array(
     'static' => true,
     'parent' => true,
     'self'   => true,
   );
   if (isset($magic_names[$name_concrete])) {
     continue;
   }
   $need[] = array(
     'type'    => 'class',
     'symbol'  => $name,
   );
 }
 
 
 // -(  Interfaces  )------------------------------------------------------------
 
 
 // Find interfaces declared in ths file.
 
 
 // This is "interface X .. { ... }".
 $interfaces = $root->selectDescendantsOfType('n_INTERFACE_DECLARATION');
 foreach ($interfaces as $interface) {
   $interface_name = $interface->getChildByIndex(1);
   $have[] = array(
     'type'      => 'interface',
     'symbol'    => $interface_name,
   );
 }
 
 
 // Find interfaces used by this file. We identify these:
 //
 //  - class ... implements X
 //  - interface ... extends X
 
 
 // This is "class X ... { ... }".
 $classes = $root->selectDescendantsOfType('n_CLASS_DECLARATION');
 foreach ($classes as $class) {
   $class_name = $class->getChildByIndex(1)->getConcreteString();
   $implements = $class->getChildByIndex(3);
   $interfaces = $implements->selectDescendantsOfType('n_CLASS_NAME');
   foreach ($interfaces as $interface) {
     $need[] = array(
       'type'    => 'interface',
       'symbol'  => $interface,
     );
 
     // Track 'class ... implements' in the extension map.
     $xmap[$class_name][] = $interface->getConcreteString();
   }
 }
 
 
 // This is "interface X ... { ... }".
 $interfaces = $root->selectDescendantsOfType('n_INTERFACE_DECLARATION');
 foreach ($interfaces as $interface) {
   $interface_name = $interface->getChildByIndex(1)->getConcreteString();
 
   $extends = $interface->getChildByIndex(2);
   foreach ($extends->selectDescendantsOfType('n_CLASS_NAME') as $parent) {
     $need[] = array(
       'type'    => 'interface',
       'symbol'  => $parent,
     );
 
     // Track 'interface ... extends' in the extension map.
     $xmap[$interface_name][] = $parent->getConcreteString();
   }
 }
 
 
 // -(  Analysis  )--------------------------------------------------------------
 
 
 $declared_symbols = array();
 foreach ($have as $key => $spec) {
   $name = $spec['symbol']->getConcreteString();
   $declared_symbols[$spec['type']][$name] = $spec['symbol']->getOffset();
 }
 
 $required_symbols = array();
 foreach ($need as $key => $spec) {
   $name = idx($spec, 'name');
   if (!$name) {
     $name = $spec['symbol']->getConcreteString();
   }
 
   $type = $spec['type'];
   if (!$show_all) {
     if (!empty($externals[$type][$name])) {
       // Ignore symbols declared as externals.
       continue;
     }
     if (!empty($builtins[$type][$name])) {
       // Ignore symbols declared as builtins.
       continue;
     }
   }
   if (!empty($required_symbols[$type][$name])) {
     // Report only the first use of a symbol, since reporting all of them
     // isn't terribly informative.
     continue;
   }
   if (!empty($declared_symbols[$type][$name])) {
     // We declare this symbol, so don't treat it as a requirement.
     continue;
   }
   $required_symbols[$type][$name] = $spec['symbol']->getOffset();
 }
 
 $result = array(
   'have'  => $declared_symbols,
   'need'  => $required_symbols,
   'xmap'  => $xmap,
 );
 
 
 // -(  Output  )----------------------------------------------------------------
 
 
 if ($args->getArg('ugly')) {
   echo json_encode($result);
 } else {
   $json = new PhutilJSON();
   echo $json->encodeFormatted($result);
 }
 
 
 // -(  Library  )---------------------------------------------------------------
 
 
 function phutil_symbols_get_builtins() {
   $builtin_classes    = get_declared_classes();
   $builtin_interfaces = get_declared_interfaces();
   $builtin_functions  = get_defined_functions();
   $builtin_functions  = $builtin_functions['internal'];
 
   return array(
     'class'     => array_fill_keys($builtin_classes, true) + array(
       'PhutilBootloader' => true,
     ),
     'function'  => array_filter(
       array(
         'empty' => true,
         'isset' => true,
         'die'   => true,
 
         // These are provided by libphutil but not visible in the map.
 
         'phutil_is_windows'   => true,
         'phutil_load_library' => true,
         'phutil_is_hiphop_runtime' => true,
 
         // HPHP/i defines these functions as 'internal', but they are NOT
         // builtins and do not exist in vanilla PHP. Make sure we don't mark
         // them as builtin since we need to add dependencies for them.
         'idx'   => false,
         'id'    => false,
       ) + array_fill_keys($builtin_functions, true)),
     'interface' => array_fill_keys($builtin_interfaces, true),
   );
 }