More precise hash return type

[VincentLanglet]

Follow up of #3541 (cc @staabm)

Currently md5('foo') is considered non-falsy-string&lowercase-string, but hash('md5', 'foo') is still non-empty-string.

At first, I planned to list hash algo with lowercase output, but

• I tried

foreach (hash_algos() as $algo) {
     var_dump(hash($algo, ''));
}

and get everytime a non-falsy-string and lowercase-string (when binary is false)

• My research on internet/chatGPT give the same result.

So it seems like it's always non-falsy-string&lowercase-string with binary false, and non-falsy-string when binary true.

[mvorisek]

https://www.php.net/manual/en/function.hash.php - must be conditional return, when $binary flag is set, the string can be anything (contain UC easily)

[VincentLanglet]

Thanks ! I updated the PR, please take a new look

[mvorisek]

I am still not sure if non-falsy-string in the functionMap.php is correct as short hash functions like crc32 can quite easily produce falsy string.

[staabm]

@mvorisek can you show an example on 3v4l.org ?

[mvorisek]

https://3v4l.org/Bo2AT

[staabm]

so your examples shows us a case where it is non-falsy-string - which is the opposite of your thesis?

crc32 can quite easily produce falsy string

[mvorisek]

You are right! '00..' is non-falsy-string per https://www.php.net/manual/en/language.types.boolean.php#language.types.boolean.casting but only '00..' == 0 is true.

[staabm]

AFAIK every string with more then 1 char is non-falsy-string

[phpstan-bot]

This pull request has been marked as ready for review.

[VincentLanglet]

What do you think about this PR @ondrejmirtes ?

If preferred, I can use non-empty-string rather than non-falsy-string in order to be safer (?)

[ondrejmirtes]

Thank you!