This isn't great. If the inputs are correct, users shouldn't be forced to handle null.

After some try, password_hash returns null

• if the second parameter is not PASSWORD_DEFAULT| PASSWORD_BCRYPT| PASSWORD_ARGON2I| PASSWORD_ARGON2ID
• if the second parameter is PASSWORD_DEFAULT| PASSWORD_BCRYPT and the salt option is not a 22-length string
• if the second parameter is PASSWORD_DEFAULT|PASSWORD_BCRYPT and the cost option is not int<4, 31>
• if the second parameter is PASSWORD_ARGON2I| PASSWORD_ARGON2ID and ext-libargon2 is not installed
• if the second parameter is PASSWORD_ARGON2I| PASSWORD_ARGON2ID and the memory_cost/time_cost/threads is not a correct int but I don't know all the allowed values.

This won't be an easy dynamicReturnTypeExtension...

This isn't great. If the inputs are correct, users shouldn't be forced to handle null.

I understand, but currently PHP 7.4 users are already forced to handle false
https://phpstan.org/r/5464625f-1925-4c4d-a8c5-7aea19ace58f

When I looked at
https://stackoverflow.com/questions/39729941/php-password-hash-returns-false
https://bugs.php.net/bug.php?id=77218
we find that

So basically, for PHP ≤ 7.3, the function returned FALSE for a
failing implementation, and NULL for invalid parameters in
combination with a warning (the latter likely according to the
general convention to return NULL on ZPP failures).

So even without dynamicReturnTypeExtension it would be more useful (and correct ?) for functionMap_php74delta.php to have

- 'password_hash' => ['string|false', 'password'=>'string', 'algo'=>'string|null', 'options='=>'array'],
+ 'password_hash' => ['string|null', 'password'=>'string', 'algo'=>'string|null', 'options='=>'array'],

while I can let

'password_hash' => ['string|false', 'password'=>'string', 'algo'=>'string|null', 'options='=>'array'],

for the original functionMap_php.

Would you be ok with this first step ?

I'd just do benevolent union of string|false|null and call it a day.

I'd just do benevolent union of string|false|null and call it a day.

Nice idea. Done :)

Thank you!