Intersection types not working in generics

[danog]

https://psalm.dev/r/542b1e4b94

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/542b1e4b94

<?php
interface a {}

class b {
    public function custom(): int {
        return 0;
    }
}

class c extends b implements a {}

/**
 * @template T as (a&b)
 */
class d {
    /**
     * @param T $param
     */
    public function test(b $param): void {
        echo $param->custom();
    }
}

/** @extends d<c> */
class e extends d {
}

Psalm output (using commit 9168cef):

ERROR: PossiblyUndefinedMethod - 20:22 - Method a::custom does not exist

INFO: MixedArgument - 20:14 - Argument 1 of echo cannot be mixed, expecting string

[wooky]

Specifically, only the first type of an intersection is considered, with the rest being discarded. So in this case, if we write @template T as (b&a), there would be no issues, but then a's methods would be unresolved.