#[ReturnTypeWillChange] does not report an error when used on non-built ins and also causes MethodSignatureMismatch to not report on built-ins

[kkmuffme]

psalm.dev/r/281be02fc0

#[ReturnTypeWillChange] only works on built-ins, should report an error when used on non-built ins

Also psalm does not report an error when #[ReturnTypeWillChange] is used on non-built ins and no return type is specified - this must report an error, since it will be a fatal error when the code is actually run

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/281be02fc0

<?php

abstract class A {
    /**
     * @param array{hello: int|non-empty-string, world: array}|false $arg
     * @param string $b
     * @return array{hello: int|non-empty-string, world: array}|false
     */
    abstract public function run( array|false $arg, string $b ): array|false;   
}

class B extends A {
    /**
     * @param array{hello: int|non-empty-string, world: array}|false $arg
     * @param string $b
     * @return array{hello: int|non-empty-string, world: array}|false
     */
    #[ReturnTypeWillChange]
    public function run( array|false $arg, string $b ): array|false {
     	if ( rand( 0, 1 ) ) {
            return false;
        }
        
        return $arg;
    }
}

Psalm output (using commit 491dd74):

ERROR: MissingAbstractPureAnnotation - 9:30 - run must be marked with one of @psalm-pure, @psalm-mutation-free, @psalm-external-mutation-free, @psalm-impure to aid security analysis