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<?php declare(strict_types=1); const DEFAULT_VALUE = null; function foo(bool $arg = DEFAULT_VALUE) { var_dump($arg); } var_dump((new ReflectionFunction('foo'))->getParameters()[0]->allowsNull());
Output for 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
bool(false)

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79.66 ms | 1390 KiB | 4 Q