Polymorphic anonymous functions

[klimick]

Bug report

The new feature for callable type from 1.10.60 release does not work well.

Most easiest case of usage:
https://phpstan.org/r/870d442a-918b-4ea8-8181-afe38d8faae2

Type representation dumps incorrectly:
https://phpstan.org/r/294502a4-683d-4dc7-a7f5-24b07291ec22

Other (can be mind blowing):
https://phpstan.org/r/0efe72eb-b394-4de7-b2d5-a04f59fe6667
https://phpstan.org/r/15a337f8-fdcc-484c-9db0-766ed55740b0

Code snippet that reproduces the problem

No response

Expected output

I tried to describe it in examples

Did PHPStan help you today? Did it make you happy in any way?

No response

[mad-briller]

in your flip-zip example, are you sure that the expected output is list<array{1, 2}> and not list<array{2, 1}> ?

it's hard to tell without the code bodies, but assuming the parameters become flipped, the result should be backwards right?
https://3v4l.org/KtRie

[klimick]

in your flip-zip example, are you sure that the expected output is list<array{1, 2}> and not list<array{2, 1}> ?

You right. Expected output should be list<array{2, 1}>.
It seems I was in a hurry with the issue writing. Sorry.
I checked it with TypeScript. Link to playground.

it's hard to tell without the code bodies, but assuming the parameters become flipped, the result should be backwards right?

Right. You guessed what the functions do.
It's classic from functional programming.

[phpstan-bot]

@klimick After the latest push in 1.11.x, PHPStan now reports different result with your code snippet:

@@ @@
-PHP 8.1 – 8.3 (1 error)
+PHP 8.1 – 8.3 (2 errors)
 ==========
 
-26: Dumped type: Closure(A): A
+26: Dumped type: Closure<A of mixed>(A): A
+28: Call to function acceptsPoly() on a separate line has no effect.
 
-PHP 7.2 – 8.0 (2 errors)
+PHP 7.2 – 8.0 (3 errors)
 ==========
 
 22: First-class callables are supported only on PHP 8.1 and later.
-26: Dumped type: Closure(A): A
+26: Dumped type: Closure<A of mixed>(A): A
+28: Call to function acceptsPoly() on a separate line has no effect.

Full report

PHP 8.1 – 8.3 (2 errors)

Line	Error
26	Dumped type: Closure<A of mixed>(A): A
28	Call to function acceptsPoly() on a separate line has no effect.

PHP 7.2 – 8.0 (3 errors)

Line	Error
22	First-class callables are supported only on PHP 8.1 and later.
26	Dumped type: Closure<A of mixed>(A): A
28	Call to function acceptsPoly() on a separate line has no effect.

[phpstan-bot]

@klimick After the latest push in 1.11.x, PHPStan now reports different result with your code snippet:

@@ @@
 
 32: Dumped type: callable(list<B>, list<A>): list<array{A, B}>
 36: Dumped type: list<array{2, 2}>
-37: Parameter #1 $ of callable callable(list<B>, list<A>): list<array{A, B}> expects list<2>, array{1} given.
+37: Parameter #1 of callable callable(list<B>, list<A>): list<array{A, B}> expects list<2>, array{1} given.
 
 PHP 7.2 – 8.0 (4 errors)
 ==========
@@ @@
 29: First-class callables are supported only on PHP 8.1 and later.
 32: Dumped type: callable(list<B>, list<A>): list<array{A, B}>
 36: Dumped type: list<array{2, 2}>
-37: Parameter #1 $ of callable callable(list<B>, list<A>): list<array{A, B}> expects list<2>, array{1} given.
+37: Parameter #1 of callable callable(list<B>, list<A>): list<array{A, B}> expects list<2>, array{1} given.

Full report

PHP 8.1 – 8.3 (3 errors)

Line	Error
32	Dumped type: callable(list<B>, list<A>): list<array{A, B}>
36	Dumped type: list<array{2, 2}>
37	Parameter #1 of callable callable(list<B>, list<A>): list<array{A, B}> expects list<2>, array{1} given.

PHP 7.2 – 8.0 (4 errors)

Line	Error
29	First-class callables are supported only on PHP 8.1 and later.
32	Dumped type: callable(list<B>, list<A>): list<array{A, B}>
36	Dumped type: list<array{2, 2}>
37	Parameter #1 of callable callable(list<B>, list<A>): list<array{A, B}> expects list<2>, array{1} given.