Fix template parameter collection for child classes with fewer parameters (fixes #6734)

[danog]

No description provided.

[orklah]

Can you explain in a few words what was the issue and how you fixed it? It helps with the review. I'm not familiar with a lot of those classes, particularly for templates

Thanks :)

[danog]

This is actually my first time touching this part of psalm's codebase, but I think I pinpointed&fixed the issue: some extremely weird and non-generic logic was used when resolving template parameters, which completely failed especially with recursive templates with different parameter names, or when the order or number of the parameters was different in child classes, or when a union of template types was used when extending a parent template type: https://psalm.dev/r/aa45e698db

This PR fixes all of the issues listed above :)

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/aa45e698db

<?php
                    class Real {}
                    
                    class RealE extends Real {}
                    
                    /**
                     * @template TKey as array-key
                     * @template TValue as object
                     */
                    class a {
                        /** 
                         * @param TKey $key
                         * @param TValue $real
                         */
                        public function __construct(public int|string $key, public object $real) {}
                        /**
                         * @return TValue
                         */
                        public function ret(): object {
                            return $this->real;
                        }
                    }
                    /**
                     * @template TTKey as array-key
                     * @template TTValue as object
                     *
                     * @extends a<TTKey, TTValue>
                     */
                    class b extends a {
                    }
                    
                    /**
                     * @template TObject as Real
                     *
                     * @extends b<string, TObject>
                     */
                    class c1 extends b {
                        /**
                         * @param TObject $real
                         */
                        public function __construct(object $real) {
                            parent::__construct("", $real);
                        }
                    }
                    
                    /**
                     * @template TObject as Real
                     * @template TOther
                     *
                     * @extends b<string, TObject>
                     */
                    class c2 extends b {
                        /**
                         * @param TOther $other
                         * @param TObject $real
                         */
                        public function __construct($other, object $real) {
                            parent::__construct("", $real);
                        }
                    }
                    
                    /**
                     * @template TOther as object
                     * @template TObject as Real
                     *
                     * @extends b<string, TObject|TOther>
                     */
                    class c3 extends b {
                        /**
                         * @param TOther $other
                         * @param TObject $real
                         */
                        public function __construct(object $other, object $real) {
                            parent::__construct("", $real);
                        }
                    }
                    
                    $a = new a(123, new RealE);
/** @psalm-trace $resultA */
                    $resultA = $a->ret();
                    
                    $b = new b(123, new RealE);

/** @psalm-trace $resultB */
                    $resultB = $b->ret();
                    
                    $c1 = new c1(new RealE);

/** @psalm-trace $resultC1 */
                    $resultC1 = $c1->ret();
                    
                    $c2 = new c2(false, new RealE);

/** @psalm-trace $resultC2 */
                    $resultC2 = $c2->ret();
                    
                    
                    class Secondary {}
                    
                    $c3 = new c3(new Secondary, new RealE);
/** @psalm-trace $resultC3 */
                    $resultC3 = $c3->ret();

Psalm output (using commit 6fba5eb):

INFO: Trace - 80:21 - $resultA: RealE

INFO: Trace - 85:21 - $resultB: RealE

INFO: Trace - 90:21 - $resultC1: object

INFO: Trace - 95:21 - $resultC2: false

INFO: Trace - 102:21 - $resultC3: RealE

INFO: UnusedVariable - 80:21 - $resultA is never referenced or the value is not used

INFO: UnusedVariable - 85:21 - $resultB is never referenced or the value is not used

INFO: UnusedVariable - 90:21 - $resultC1 is never referenced or the value is not used

INFO: UnusedVariable - 95:21 - $resultC2 is never referenced or the value is not used

INFO: UnusedVariable - 102:21 - $resultC3 is never referenced or the value is not used

[orklah]

Thanks!