TYPO3 Core

Update: This fatal only occures if composer class loading is not used.

If you are not using composer class loading, you can nail it down to the slots being registered (and called) in sysext:core ext_localconf.php lines 43-60

if (!\TYPO3\CMS\Core\Core\Bootstrap::usesComposerClassLoading()) {
    $bootstrap = \TYPO3\CMS\Core\Core\Bootstrap::getInstance();
    $classAliasMap = $bootstrap->getEarlyInstance(\TYPO3\CMS\Core\Core\ClassAliasMap::class);
    $signalSlotDispatcher->connect(
        \TYPO3\CMS\Extensionmanager\Service\ExtensionManagementService::class,
        'hasInstalledExtensions',
        $classAliasMap,
        'buildStaticMappingFile'
    );

    $signalSlotDispatcher->connect(
        \TYPO3\CMS\Extensionmanager\Utility\InstallUtility::class,
        'afterExtensionUninstall',
        $classAliasMap,
        'buildStaticMappingFile'
    );
    unset($bootstrap, $classAliasMap);
}

If you skip this code, the fatal disappears.

So far, I encountered that error on the following setups:

• OSX 10.10.3 - PHP 5.5.21
• CentOS release 6.6 - PHP 5.5.22

Composer class loading was not used in either setup.

• Ubuntu 14.04.2 - PHP 5.5.9-1ubuntu4.9

How do you "disable" Composer class loading?
master always uses the composer class loader for Core classes.

The core checks for the composer autoload.php only at one place (code is from \TYPO3\CMS\Core\Core\Bootstrap line 216ff):

static protected function initializeComposerClassLoader() {
    $possiblePaths = array(
        'distribution' => __DIR__ . '/../../../../../../Packages/Libraries/autoload.php',
        'fallback' => __DIR__ . '/../../../../contrib/vendor/autoload.php',
    );
[...]

(It is the distribution array key)

So only if in your documentRoot the folders ./Packages/Libraries/ exist and are used as composers vendor folder (you have to configure this in your composer.json) only then is composer class loading used.

[...]
if ($autoLoadType === 'distribution') {
    self::$usesComposerClassLoading = TRUE;
}
[...]

So to "disable" composer class loading you just have to make composer use its default vendor folder "vendor".

I'm still not fully clear about how you use the Core.

Did you install it the "classic" way by downloading the source, or are you using it as "library" in a distribution defining a project-level composer.json?

My workflow is simple:
To initialize a TYPO3 Website I create a composer.json like this:

{
  "name": "danielgoerz/newProject",
  "description": "New awesome TYPO3 project",
  "homepage": "link to git repo",
  "config": {
    "vendor-dir": "Packages/Libraries/" 
  },
  "repositories": [
    {"type": "composer", "url": "http://composer.typo3.org"}
  ],
  "require": {
    "typo3/cms": "7.2.*",

    // Extensions go here
  }
}

composer update now pretty much does the trick.

You see the vendor-dir thingy in the composer.json

I'm finally totally confused.

You're using the Core via composer, but above you said

Composer class loading was not used in either setup

That does not make sense to me.

Additionally, the Core now dropped the internal class loader completely, so maybe you can give this another shot with current master.

Well, it does make sense, because the core looks only in Packages/Libraries/ if a autoload.php exists.
If I dont specify this vendor-dir in my composer.json, composer will put its autoload.php inside the vendor directory by default.

And in that case I use the core with composer but internally (in \TYPO3\CMS\Core\Core\Bootstrap) self::$usesComposerClassLoading will always be FALSE.
And that is what I ment with " Composer class loading was not used ".

I didnt ment to confuse you, but this is kind of a confusing topic to me, too. I dont know how to explain it better =)

Got that now. The point is: You posted a json with vendor-dir, but you actually use it without vendor-dir.
That will not work.

On current master I am not able to reproduce the fatal.
So I guess we can close this issue?