InvalidDocblock error when comparing array with special characters in string keys

[theodorejb]

I have a PHPUnit test that asserts that an array<string, int> array in an object property matches the expected value. However, if the expected value contains special characters in its string keys, Psalm reports an error saying the array cannot be used in an assertion:

https://psalm.dev/r/d3c81c61d3

This worked fine in Psalm 4.14 and then broke starting in Psalm 4.15.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/d3c81c61d3

<?php

class Foo {
    /** @var array<string, int> */
    public array $bar;
    
    /**
     * @param array<string, int> $bar
     */
    public function __construct(array $bar) {
        $this->bar = $bar;
    }
}

$expected = [
    '#[]' => 21,
    '<<>>' => 6,
];

$foo = new Foo($expected);
assertSame($expected, $foo->bar);

/**
 * @psalm-template ExpectedType
 * @psalm-param ExpectedType $expected
 * @psalm-assert =ExpectedType $actual
 */
function assertSame($expected, $actual): void {
    if ($expected !== $actual) {
        throw new Exception("Expected doesn't match actual");
    }
}

Psalm output (using commit aa7e400):

ERROR: InvalidDocblock - 21:1 - array{#[]: 21, <<>>: 6} cannot be used in an assertion

INFO: MissingParamType - 28:32 - Parameter $actual has no provided type

[orklah]

This is related to #7076 that drastically improved the way assertions for arrays works. This seems related to escaping some chars in the string representation of the array. I'll try to check that.