Pass through to facts (#72)

* Documentation update
Remove implied comparisons to composer autoloading.
Remove statement about global namespace fallback.
Document interactions with native autoloaders.
Document HH\Facts mode (not present in this commit).

* [Untested] Emit an HH\Facts autoload map
May still need to lowercase the names.
Will check in a Facts-enabled docker container.

* Lowercase the names and call the right functions

* Parens

* Escape `HH\Facts`, no need for a random form feed

* Rename useFactsIfAvailableAndDoNotEmitAStaticMap
Now named useFactsIfAvailable

* Support hhvm 4.109 and up
Hhvm 4.116 and below need a HH_FIXME.
Hhvm 4.117 has the hhi and the code typechecks on 4.117.

* Update HH_FIXME messages
The ext-facts hhi didn't make the cut for 4.117.

.github/workflows/build-and-test.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         os: [ ubuntu , macos ]
         hhvm:
-          - '4.67'
+          - '4.109'
           - latest
           - nightly
     runs-on: ${{matrix.os}}-latest

README.md

@@ -5,10 +5,11 @@ The autoloader for autoloading classes, enums, functions, typedefs, and constant
 Usage
 =====
 
-1. Add an `hh_autoload.json` file (see section below) and optionally remove your configuration from composer.json
+1. Add an `hh_autoload.json` file (see section below)
 2. `composer require hhvm/hhvm-autoload`
-3. Replace any references to `vendor/autoload.php` with  `vendor/autoload.hack` and call `Facebook\AutoloadMap\initialize()`
-4. To re-generate the map, run `vendor/bin/hh-autoload`, `composer dump-autoload`, or any other command that generates the map
+3. Require the autoload file from your entrypoint functions using `require_once (__DIR__ . '(/..)(repeat as needed)/vendor/autoload.hack');`
+4. Call `Facebook\AutolaodMap\initialize()` to register the autoloader with hhvm.
+5. To re-generate the map, run `vendor/bin/hh-autoload`, `composer dump-autoload`, or any other command that generates the map
 
 Configuration (`hh_autoload.json`)
 ==================================
@@ -32,9 +33,10 @@ The following settings are optional:
  - `"includeVendor": false` - do not include `vendor/` definitions in `vendor/autoload.hack`
  - `"devRoots": [ "path/", ...]` - additional roots to only include in dev mode, not when installed as a dependency.
  - `"relativeAutoloadRoot": false` - do not use a path relative to `__DIR__` for autoloading. Instead, use the path to the folder containing `hh_autoload.json` when building the autoload map.
- - `"failureHandler:" classname<Facebook\AutoloadMap\FailureHandler>` - use the specified class to handle definitions that aren't the Map. Your handler will not be invoked for functions or constants
-   that aren't in the autoload map and have the same name as a definition in the global namespace. Defaults to none.
+ - `"failureHandler:" classname<Facebook\AutoloadMap\FailureHandler>` - use the specified class to handle definitions that aren't the Map. Defaults to none.
  - `"devFailureHandler": classname<Facebook\AutoloadMap\FailureHandler>` - use a different handler for development environments. Defaults to the same value as `failureHandler`.
+ - `"parser:" any of [ext-factparse]"` - select a parser to use, but there is only one valid option. Defaults to a sensible parser.
+ - `"useFactsIfAvailable": false` - use ext-facts (HH\Facts\...) to back Facebook\AutoloadMap\Generated\map() instead of a codegenned dict. See _Use with HH\Facts_ for more information about this mode.
 
 Use In Development (Failure Handlers)
 =====================================
@@ -90,12 +92,24 @@ Information you may need is available from:
  - `Facebook\AutoloadMap\Generated\root()`: the directory containing the
     project root, i.e. the parent directory of `vendor/`
 
+Use with HH\\Facts
+=================
+
+HHVM 4.109 introduced ext-facts and ext-watchman. Unlike the static pre-built autoloader which is built into a [repo authoratative](https://docs.hhvm.com/hhvm/advanced-usage/repo-authoritative) build, this native autoloader works incrementally and is suitable for autoloading in your development environment. For more information about setting up this autoloader, see the [blog post](https://hhvm.com/blog/2021/05/11/hhvm-4.109.html) for hhvm 4.109.
+
+When using a native autoloader (either the repo auth or ext-facts autoloader), you do not need hhvm-autoload to require classes/functions/types/constants at runtime. If you (and your vendor dependencies) do not call any functions in the `Facebook\AutoloadMap` namespace, other than `Facebook\AutoloadMap\initialize()`, you don't need hhvm-autoload anymore. In that case, you could drop this dependency and remove the calls to `initialize()`. If you are using other functions, like `Facebook\AutoloadMap\Generated\map()`, you'd still need the vendor/autoload.hack file that hhvm-autoload generates.
+
+Hhvm-autoload supports outputting a vendor/autoload.hack file which forwards all queries to ext-facts. `Facebook\AutoloadMap\Generated\map_uncached()` will always be up to date in this mode, since `HH\Facts` is always up to date. `Facebook\AutoloadMap\Generated\map()` is memoized (within a request), since some code may rely on getting the same result from multiple calls. You can enable this mode by adding `"useFactsIfAvailable": true` to the hh_autoload.json config file. Hhvm-autoload will emit a shim file instead of a full map. This option is ignored if `HH\Facts\enabled()` returns false, or when `--no-facts` is passed to `vendor/bin/hh-autoload`. We recommend passing `--no-facts` when building for production (specifically repo auth mode). Returning a hardcoded dict is faster than asking `HH\Facts`.
+
+Important to note. Autoloading with a native autoloader does not respect hh_autoload.json. The repo auth autoloader allows any code to use any symbol. The facts autoloader honors the configuration in .hhvmconfig.hdf instead. Make sure that the configuration in hh_autoload.json and .hhvmconfig.hdf match.
+
 How It Works
 ============
 
  - A parser (FactParse) provides a list of all Hack definitions in the specified locations
  - This is used to generate something similar to a classmap, except including other kinds of definitions
  - The map is provided to HHVM with [`HH\autoload_set_paths()`](https://docs.hhvm.com/hack/reference/function/HH.autoload_set_paths/)
+ - If a native autoloader is registered, this autoloader will intentionally not register itself. So calling `Facebook\AutoloadMap\initialize()` in repo auth mode or when the facts based autoloader is registered is a noop.
 
 Contributing
 ============

bin/hh-autoload.hack

@@ -15,6 +15,7 @@ use namespace HH\Lib\Vec;
 final class GenerateScript {
   const type TOptions = shape(
     'dev' => bool,
+    'no-facts' => bool,
   );
 
   private static function initBootstrapAutoloader(): void {
@@ -94,22 +95,28 @@ final class GenerateScript {
   private static function parseOptions(vec<string> $argv): self::TOptions {
     $options = shape(
       'dev' => true,
+      'no-facts' => false,
     );
     $bin = $argv[0];
     $argv = Vec\slice($argv, 1);
     foreach ($argv as $arg) {
-      if ($arg === '--no-dev') {
-        $options['dev'] = false;
-        continue;
-      }
-      if ($arg === '--help') {
-        self::printUsage(\STDOUT, $bin);
-        exit(0);
+      switch ($arg) {
+        case '--no-dev':
+          $options['dev'] = false;
+          break;
+        case '--no-facts':
+          $options['no-facts'] = true;
+          break;
+        case '--help':
+          self::printUsage(\STDOUT, $bin);
+          exit(0);
+        default:
+          \fprintf(\STDERR, "Unrecognized option: '%s'\n", $arg);
+          self::printUsage(\STDERR, $bin);
+          exit(1);
       }
-      \fprintf(\STDERR, "Unrecognized option: '%s'\n", $arg);
-      self::printUsage(\STDERR, $bin);
-      exit(1);
     }
+
     return $options;
   }
 
@@ -139,22 +146,37 @@ final class GenerateScript {
       $options['dev'] ? IncludedRoots::DEV_AND_PROD : IncludedRoots::PROD_ONLY,
     );
 
+    $config = $importer->getConfig();
+
     $handler = $options['dev']
-      ? ($importer->getConfig()['devFailureHandler'] ?? null)
-      : ($importer->getConfig()['failureHandler'] ?? null);
+      ? $config['devFailureHandler']
+      : $config['failureHandler'];
+
+    $emit_facts_forwarder_file = $config['useFactsIfAvailable'] &&
+      !$options['no-facts'];
 
     (new Writer())
       ->setBuilder($importer)
       ->setRoot(\getcwd())
-      ->setRelativeAutoloadRoot($importer->getConfig()['relativeAutoloadRoot'])
+      ->setRelativeAutoloadRoot($config['relativeAutoloadRoot'])
       ->setFailureHandler(/* HH_IGNORE_ERROR[4110] */ $handler)
       ->setIsDev($options['dev'])
+      ->setEmitFactsForwarderFile($emit_facts_forwarder_file)
       ->writeToDirectory(\getcwd().'/vendor/');
     print(\getcwd()."/vendor/autoload.hack\n");
   }
 
   private static function printUsage(resource $to, string $bin): void {
-    \fprintf($to, "USAGE: %s [--no-dev]\n", $bin);
+    \fprintf(
+      $to,
+      "USAGE: %s [--no-dev] [--no-facts]\n".
+      "See the README for full information.\n".
+      "The README can be found at:\n\t- %s\n\t- %s.\n",
+      $bin,
+      \getcwd().'/vendor/hhvm/hhvm-autoload/README.md',
+      // ^^^^^^ Not accurate if hhvm-autoload is the top level project.
+      'https://github.com/hhvm/hhvm-autoload/blob/master/README.md',
+    );
   }
 
   private static function getFileList(string $root): vec<string> {

composer.json

@@ -11,7 +11,7 @@
   ],
   "require": {
     "composer-plugin-api": "^1.0|^2.0",
-    "hhvm": "^4.67",
+    "hhvm": "^4.109",
     "hhvm/hsl": "^4.0"
   },
   "require-dev": {

src/Config.hack

@@ -19,4 +19,5 @@ type Config = shape(
   'failureHandler' => ?string,
   'devFailureHandler' => ?string,
   'relativeAutoloadRoot' => bool,
+  'useFactsIfAvailable' => bool,
 );

src/ConfigurationLoader.hack

@@ -85,6 +85,16 @@ abstract final class ConfigurationLoader {
         'devFailureHandler',
       ) ??
         $failure_handler,
+      'useFactsIfAvailable' => (
+        TypeAssert\is_nullable_bool(
+          $data['useFactsIfAvailable'] ?? null,
+          'useFactsIfAvailable',
+        ) ??
+        false
+      ) &&
+        /* HH_FIXME[2049] Facts landed in 4.109, but the hhi landed in 4.118 */
+        /* HH_FIXME[4107] Facts landed in 4.109, but the hhi landed in 4.118 */
+        \HH\Facts\enabled(),
     );
   }
 

src/Writer.hack

@@ -26,6 +26,7 @@ final class Writer {
   private bool $relativeAutoloadRoot = true;
   private ?string $failureHandler;
   private bool $isDev = true;
+  private bool $emitFactsForwarderFile = false;
 
   /** Mark whether we're running in development mode.
    *
@@ -55,6 +56,11 @@ final class Writer {
     return $this;
   }
 
+  public function setEmitFactsForwarderFile(bool $should_forward): this {
+    $this->emitFactsForwarderFile = $should_forward;
+    return $this;
+  }
+
   /** Set the files and maps from a builder.
    *
    * Convenience function; this is equivalent to calling `setFiles()` and
@@ -166,9 +172,30 @@ final class Writer {
       true,
     );
 
-    $map = \var_export($map, true)
-      |> \str_replace('array (', 'dict[', $$)
-      |> \str_replace(')', ']', $$);
+    if (!$this->emitFactsForwarderFile) {
+      $memoize = '';
+      $map_as_string = \var_export($map, true)
+        |> \str_replace('array (', 'dict[', $$)
+        |> \str_replace(')', ']', $$);
+    } else {
+      $memoize = "\n<<__Memoize>>";
+      $map_as_string = <<<'EOF'
+dict[
+    /* HH_FIXME[2049] Facts landed in 4.109, but the hhi landed in 4.118 */
+    /* HH_FIXME[4107] Facts landed in 4.109, but the hhi landed in 4.118 */
+    'class' => \HH\Lib\Dict\map_keys(\HH\Facts\all_types(), \HH\Lib\Str\lowercase<>),
+    /* HH_FIXME[2049] Facts landed in 4.109, but the hhi landed in 4.118 */
+    /* HH_FIXME[4107] Facts landed in 4.109, but the hhi landed in 4.118 */
+    'function' => \HH\Lib\Dict\map_keys(\HH\Facts\all_functions(), \HH\Lib\Str\lowercase<>),
+    /* HH_FIXME[2049] Facts landed in 4.109, but the hhi landed in 4.118 */
+    /* HH_FIXME[4107] Facts landed in 4.109, but the hhi landed in 4.118 */
+    'type' => \HH\Lib\Dict\map_keys(\HH\Facts\all_type_aliases(), \HH\Lib\Str\lowercase<>),
+    /* HH_FIXME[2049] Facts landed in 4.109, but the hhi landed in 4.118 */
+    /* HH_FIXME[4107] Facts landed in 4.109, but the hhi landed in 4.118 */
+    'constants' => \HH\Facts\all_constants(),
+  ]
+EOF;
+    }
 
     if ($this->relativeAutoloadRoot) {
       try {
@@ -206,9 +233,12 @@ function is_dev(): bool {
   return (bool) \$override;
 }
 
+function map_uncached(): \Facebook\AutoloadMap\AutoloadMap {
+  return $map_as_string;
+}
+$memoize
 function map(): \Facebook\AutoloadMap\AutoloadMap {
-  /* HH_IGNORE_ERROR[4110] invalid return type */
-  return $map;
+  return map_uncached();
 }
 
 } // Generated\