Argument 2 passed to Composer\Pcre\Preg::isMatch() must be of the type string, null given

[bartlangelaan]

In the CI (not on my machine) during a composer create-project, this error occurs:

    Exception trace:
      at /app/.global/composer/composer/vendor/composer/pcre/src/Preg.php:233
     Composer\Pcre\Preg::isMatch() at /app/.global/composer/composer/vendor/composer/composer/src/Composer/Downloader/GitDownloader.php:475
     Composer\Downloader\GitDownloader->updateToCommit() at /app/.global/composer/composer/vendor/composer/composer/src/Composer/Downloader/GitDownloader.php:138
     Composer\Downloader\GitDownloader->doInstall() at /app/.global/composer/composer/vendor/composer/composer/src/Composer/Downloader/VcsDownloader.php:137
     Composer\Downloader\VcsDownloader->install() at /app/.global/composer/composer/vendor/composer/composer/src/Composer/Downloader/DownloadManager.php:279
     Composer\Downloader\DownloadManager->install() at /app/.global/composer/composer/vendor/composer/composer/src/Composer/Installer/LibraryInstaller.php:282
     Composer\Installer\LibraryInstaller->installCode() at /app/.global/composer/composer/vendor/composer/composer/src/Composer/Installer/LibraryInstaller.php:155
     Composer\Installer\LibraryInstaller->install() at /app/.global/composer/composer/vendor/composer/composer/src/Composer/Installer/InstallationManager.php:528

I think this is related to composer/pcre@2e56743, #10662 and 0708eb4.

Looking at the code, I could see how this could possibly go wrong:

composer/src/Composer/Downloader/GitDownloader.php

Lines 455 to 458 in 10cd375

	$branches = null;
	if (0 === $this->process->execute('git branch -r', $output, $path)) {
	$branches = $output;
	}

composer/src/Composer/Downloader/GitDownloader.php

Lines 472 to 477 in 10cd375

	// try to checkout branch by name and then reset it so it's on the proper branch name
	if (Preg::isMatch('{^[a-f0-9]{40}$}', $reference)) {
	// add 'v' in front of the branch if it was stripped when generating the pretty name
	if (!Preg::isMatch('{^\s+composer/'.preg_quote($branch).'$}m', $branches) && Preg::isMatch('{^\s+composer/v'.preg_quote($branch).'$}m', $branches)) {
	$branch = 'v' . $branch;
	}

So, it seems like the $branches var is used while it is null.
However, it's hard for me to check if adding a && $branches to the outer if-statement is enough to fix this issue, because this error only happens in the CI for me. But it seems like a good thing to do anyway.

[Seldaek]

Do you not have git installed on CI, or why is it failing to execute git branch -r? Or maybe you cache vendor dir but not the .git dirs within?

I mean we need to fix this regardless, but I am curious how you reach this code path.

[brunoborghi]

Interesting...

@Seldaek, on CI after run composer install, before generating autoload files, this error occurs:

[TypeError] Argument 2 passed to Composer\Pcre\Preg::matchAll() must be of the type str ing, null given, called in phar:///.../composer.phar/vendor/composer/class-map-generator/src/PhpFil eParser.php on line 55

Trace:

Exception trace: at phar:///.../composer.phar/vendor/composer/pcre/src/Preg.php:67 Composer\Pcre\Preg::matchAll() at phar:///.../composer.phar/vendor/composer/class-map-generator/src/PhpFileParser.php:55 Composer\ClassMapGenerator\PhpFileParser::findClasses() at phar:///.../composer.phar/vendor/composer/class-map-generator/src/ClassMapGenerator.php:176 Composer\ClassMapGenerator\ClassMapGenerator->scanPaths() at phar:///.../composer.phar/src/Composer/Autoload/AutoloadGenerator.php:314 Composer\Autoload\AutoloadGenerator->dump() at phar:///.../composer.phar/src/Composer/Installer.php:343 Composer\Installer->run() at phar:///.../composer.phar/src/Composer/Command/UpdateCommand.php:240 Composer\Command\UpdateCommand->execute() at phar:///.../composer.phar/vendor/symfony/console/Command/Command.php:298 Symfony\Component\Console\Command\Command->run() at phar:///.../composer.phar/vendor/symfony/console/Application.php:1028 Symfony\Component\Console\Application->doRunCommand() at phar:///.../composer.phar/vendor/symfony/console/Application.php:299 Symfony\Component\Console\Application->doRun() at phar:///.../composer.phar/src/Composer/Console/Application.php:370 Composer\Console\Application->doRun() at phar:///.../composer.phar/vendor/symfony/console/Application.php:171 Symfony\Component\Console\Application->run() at phar:///.../composer.phar/src/Composer/Console/Application.php:138 Composer\Console\Application->run() at phar:///.../composer.phar/bin/composer:88 require() at /.../composer.phar:29

I'm using version 2.4.2. Could it have something to do with this error?
On my computer it works normally.

[Seldaek]

@brunoborghi that is an unrelated issue, but I wonder how that is possible at all. The $contents / arg #2 here https://github.com/composer/class-map-generator/blob/main/src/PhpFileParser.php#L55 should always be a string as php_strip_whitespace can only return a string, and as per https://3v4l.org/r4kMa it seems to be the case even for non-existent paths.

It doesn't make sense to me how it'd be null.