I'm working on a CI/CD pipeline where I want to catch deprecation notices and fail the build before deploying to production. However, I've discovered that Symfony's ErrorHandler explicitly excludes E_DEPRECATED and E_USER_DEPRECATED from being thrown as exceptions.

In /symfony/error-handler/ErrorHandler.php, the throwAt() method has this logic:

public function throwAt(int $levels, bool $replace = false): int
{
    $prev = $this->thrownErrors;
    $this->thrownErrors = ($levels | \E_RECOVERABLE_ERROR | \E_USER_ERROR) & ~\E_USER_DEPRECATED & ~\E_DEPRECATED;
    if (!$replace) {
        $this->thrownErrors |= $prev;
    }
    $this->reRegister($prev | $this->loggedErrors);

    return $prev;
}

The & ~\E_USER_DEPRECATED & ~\E_DEPRECATED part explicitly prevents deprecations from being thrown as exceptions.

My use case:

• I have a GitHub Actions workflow that builds my Symfony application
• I want to detect deprecation notices during the build process
• If any deprecations are found, I want the build to fail (exit code != 0)
• This ensures deprecated code never reaches production

Questions:
Is there a recommended way to make deprecations throw exceptions in specific environments (like build or test)? Or are there alternative approaches I should consider for CI/CD deprecation detection?

I understand that deprecations are typically meant to be warnings rather than fatal errors in normal operation, but for CI/CD purposes, having them fail builds would be extremely valuable for maintaining code quality.

Thanks for any guidance!