make `TypeInterface::assert`, `TypeInterface::coerce` and `TypeInterface::assert` emit `function.alreadyNarrowedType`

[bendavies]

Hi,

Similar to how \assert(...) works (https://phpstan.org/r/1a64fa56-fe04-47d5-a2ed-ef82e2206248), it would be nice if TypeInterface::assert, TypeInterface::coerce and TypeInterface::assert emitted the same errors, alerting the developer to when Type assertions are not necessary.

Thanks!

[ondrejmirtes]

Please show a specific PHP code using PSL for which you expect "always true" error to be reported.

[bendavies]

<?php

use Psl\Type;

class Foo{}

Type\instance_of(Foo::class)->assert(new Foo());
Type\instance_of(Foo::class)->matches(new Foo());
Type\instance_of(Foo::class)->coerce(new Foo());
Type\int()->assert(1);
Type\int()->matches(1);
Type\int()->coerce(1);
// repeat for as many implementation of `TypeInterface` as possible

[ondrejmirtes]

Right now this one is reported:

 ------ --------------------------------------------------------------------------------------------
  Line   test.php
 ------ --------------------------------------------------------------------------------------------
  11     Call to method Psl\Type\TypeInterface<int>::matches() with 1 will always evaluate to true.
         🪪  method.alreadyNarrowedType
 ------ --------------------------------------------------------------------------------------------

[ondrejmirtes]

If I isolate the examples like this:

function (): void {
	Type\instance_of(Foo::class)->assert(new Foo());
};

function (): void {
	Type\instance_of(Foo::class)->matches(new Foo());
};

function (): void {
	Type\instance_of(Foo::class)->coerce(new Foo());
};

function (): void {
	Type\int()->assert(1);
};

function (): void {
	Type\int()->matches(1);
};

function (): void {
	Type\int()->coerce(1);
};

both matches examples are reported:

 ------ ----------------------------------------------------------------------------------------------
  Line   test.php
 ------ ----------------------------------------------------------------------------------------------
  12     Call to method Psl\Type\TypeInterface<Foo>::matches() with Foo will always evaluate to true.
         🪪  method.alreadyNarrowedType
  24     Call to method Psl\Type\TypeInterface<int>::matches() with 1 will always evaluate to true.
         🪪  method.alreadyNarrowedType
 ------ ----------------------------------------------------------------------------------------------

[ondrejmirtes]

Not sure from the top of my head where it's getting lost. The logic is in https://github.com/phpstan/phpstan-src/blob/2.1.x/src/Rules/Comparison/ImpossibleCheckTypeHelper.php called from https://github.com/phpstan/phpstan-src/blob/2.1.x/src/Rules/Comparison/ImpossibleCheckTypeMethodCallRule.php#L90. Feel free to debug that.

[bendavies]

the isolation is interesting.
on its own, this will error:

<?php

use Psl\Type;

class Foo{}

Type\instance_of(Foo::class)->matches(new Foo());

but this won't:

<?php


use Psl\Type;

class Foo{}

Type\instance_of(Foo::class)->assert(new Foo());
Type\instance_of(Foo::class)->matches(new Foo());