[SanderMuller]

Rector will fork its own parallel workers. A forked child has to end with _exit(), and only the turbo extension has it, as PHPStanTurbo\Runtime::exitImmediately(). That class is not part of the API, and the phar has no stub for it.

This moves exitImmediately() to PHPStan\Turbo\ForkedChild, a shadowed class marked @api. The native class in ForkedChild.cpp calls _exit() with the engine's exit status, as before. The PHP twin throws the new @api TurboNotActiveException. ForkedChildTerminator calls the new class and still checks TurboExtensionEnabler::isActive() first.

The class is not called Runtime. The differential tests declare a native twin as PHPStanTurbo\ plus its short name, which would collide with the bootstrap class PHPStanTurbo\Runtime. The other Runtime methods stay in analysis-stub.php: TurboExtensionEnabler calls them before shadowing is active, so they cannot go through a twin.

turbo-ext/tests/exit-immediately.php now calls the native class through the prefixed declaration and checks that the twin throws. When the native method does nothing, the test fails.

exitImmediately() declares never in PHPDoc only. PHP before 8.1 reads a native never as a class name, and the downgrade has no rule for it.

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[ondrejmirtes]

Thank you!