Parentheses in callable syntax are not interpreted correctly

[mabar]

Parentheses in callables in some cases create unexpected results, like (Closure(): int|null) changing to (Closure(): int)|null https://phpstan.org/r/f0db1360-c01a-4884-8c17-1caa7d464852

[JanTvrdik]

Parentheses in callable syntax are not interpreted correctly

That's nonsence. The syntax is ambigous, there cannot be a correct way to interpret it.

Maybe related https://github.com/phpstan/phpdoc-parser/pull/18 (it was a long time ago, so I'm not 100 % sure)

[JanTvrdik]

Also note that top-level parentheses always have no effect, i.e. (Closure(): int|null) will aways be identical to Closure(): int|null. It's the same as in math, 1 equals to (1) equals to ((1))

[mabar]

Please check the f() and g() examples. Closure(): (int|null)|null is shown by phpstan as (Closure(): int|null)|null. If you use same syntax as is displayed by phpstan, result is (Closure(): int)|null.

I don't mind if parentheses are supported (even useless) or forbidden, but now it fails silently and phpstan is using in errors syntax which is not supported by phpstan parser.

[JanTvrdik]

So the issue in how we print the type?

[mabar]

And failing silently in case of not supported syntax. (Closure(): int|null)|null -> (Closure(): int)|null

Ideally Closure():int|null should fail too, because it's unclear whether user wanted Closure(): (int|null) or Closure(): (int)|null

[JanTvrdik]

And failing silently in case of not supported syntax.

I don't understand. (Closure(): int|null)|null is supported and parsed well. What would you expect? It's parsed as (((Closure(): int)|null)|null) and further normalized by removing the duplicated null in union type.

should fail too, because it's unclear

I think ut's allowed mostly for null|Closure():int. Anyway I think that's was #18 was supposed to solve.

[mabar]

I don't think so. (Closure(): int|string)|null turns into (Closure(): int)|string|null

https://phpstan.org/r/04ea77ae-c31d-4036-807a-9de7274fe15e

[JanTvrdik]

Yes, that is correct, even though it can be confusing. What would you expect? Note that the parentheses here are useless.

(A|B)|C is the same as A|B|C and also same as (A)|B|C. Here the A is Closure(): int.

[mabar]

(Closure(): int|string)|null turns into (Closure(): int)|string|null

One is closure which returns int|string or null, second is closure which returns int or string or null.

In following example is expected closure which returns int|string or null and as such is the code treated. If it was the same, this code would not fail. https://phpstan.org/r/58aa23f2-e350-4760-b8f0-2c5cc1bd66b8 http://sandbox.onlinephpfunctions.com/code/108b92d91ec897d01054c530ab461f47c0ef515a

Also thanks, just found another bug due to testing the Closure(): (int|string)|null syntax https://phpstan.org/r/fe407cba-17cf-4f56-8a0a-07d68cb41712 http://sandbox.onlinephpfunctions.com/code/3072c54f802558ace446341a9326c44a7a37b794

[JanTvrdik]

One is closure which returns int|string or null

Based on what? Is that you wish? Again parsing Closure(): int|string as (Closure(): int)|string is not a bug. It's very much intentional. See https://github.com/phpstan/phpdoc-parser/blob/c37ba6f7b3d30406f70f1416f18380bb0c6890f1/tests/PHPStan/Parser/TypeParserTest.php#L611-L620

[simPod]

I've run this through typescript

(a: (() => number)|string) => {
    if (typeof a === 'string') {
        return;
    }

    const x:never = a;
}

and it interprets (Closure(): int)|string not as Closure(): int|string but as Closure(): int or string. Isn't the intention here based on wrong assumption?