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<?php $value = str_repeat('a.', 126) . 'aaaa'; // 256 characters, max allowed is 253, trailing dot ignored $result = idn_to_ascii($value, 0, INTL_IDNA_VARIANT_UTS46, $idnaInfo); var_dump($result); var_dump($idnaInfo); // $idnaInfo['errors'] should be equal to 4, it is value of IDNA_ERROR_DOMAIN_NAME_TOO_LONG
Output for 5.5.0 - 5.5.37, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.31, 7.4.0 - 7.4.25, 8.0.0 - 8.0.12, 8.1rc1 - rc3
bool(false) array(0) { }

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41.72 ms | 461 KiB | 5 Q