Fatal error if composer prepend-autoloader is set to false

[legoktm]

To reproduce, create a composer.json with:

{
	"require": {
		"squizlabs/php_codesniffer": "dev-master"
	},
	"config": {
		"prepend-autoloader": false
	}
}

Run composer install. Then try vendor/bin/phpcs --version. I get the following output:

PHP Fatal error:  Uncaught Error: Class 'Composer\Autoload\ClassLoader' not found in /home/km/projects/sandbox/phpcs-test/vendor/composer/autoload_real.php:23
Stack trace:
#0 /home/km/projects/sandbox/phpcs-test/vendor/autoload.php(7): ComposerAutoloaderInit0b88db96a6b16f1b2f158f8142d34d63::getLoader()
#1 /home/km/projects/sandbox/phpcs-test/vendor/squizlabs/php_codesniffer/autoload.php(73): include('/home/km/projec...')
#2 [internal function]: PHP_CodeSniffer\Autoload::load('Composer\\Autolo...')
#3 /home/km/projects/sandbox/phpcs-test/vendor/composer/autoload_real.php(23): spl_autoload_call('Composer\\Autolo...')
#4 /home/km/projects/sandbox/phpcs-test/vendor/autoload.php(7): ComposerAutoloaderInit0b88db96a6b16f1b2f158f8142d34d63::getLoader()
#5 /home/km/projects/sandbox/phpcs-test/vendor/squizlabs/php_codesniffer/autoload.php(73): include('/home/km/projec...')
#6 [internal function]: PHP_CodeSniffer\Autoload::load('PHP_CodeSniffer...')
#7 /home/km/projects/sandbox/phpcs-test/vendor/squizlabs/php_codesniffer/bin/phpcs(17): s in /home/km/projects/sandbox/phpcs-test/vendor/composer/autoload_real.php on line 23

I found this when testing upgrading MediaWiki's CodeSniffer ruleset to 3.0. MediaWiki sets prepend-autoloader: false for performance reasons since most of our autoloaded classes are in MediaWiki's autoloader, not composer's.

[legoktm]

Here's what's happening:

• PHPCS autoloader installed
• PHP_CodeSniffer\Autoload::load() called, which tries to initialize composer's autoloader
• Composer autoloader registers itself last, then tries to autoload a Composer class
• PHPCS autoloader tries to find it, can't, and then somewhere along the way it gives up and an exception is thrown

I wonder if this is a composer bug in that the loading of \Composer\Autoload\ClassLoader should not be controlled by prepend-autoloader.

[paladox]

bump.

@gsherwood hi, could you take a look at this please?

[gsherwood]

Fixed via PR #1536