Summary

Psalm incorrectly reports an InvalidNamedArgument error when using named arguments for DateTimeImmutable::setTimestamp(timestamp: ...).

Code sample

Reproducible snippet:
https://psalm.dev/r/ff20edb0b1

<?php
(new DateTimeImmutable())->setTimestamp(timestamp: 1);

Psalm output:

ERROR: InvalidNamedArgument - 3:41 - Parameter $timestamp does not exist on function DateTimeImmutable::setTimestamp

Additional context

• PHPStan has no issues with the same code:
  https://phpstan.org/r/b71ef274-c5ba-4b50-91d6-c3912b4157bd

• PHP itself works fine at runtime, even with named argument timestamp:
  https://onlinephp.io/c/2d921

• Official PHP documentation for DateTimeImmutable::setTimestamp clearly defines $timestamp as the parameter name:
  https://www.php.net/manual/en/datetimeimmutable.settimestamp.php

• Problem in Psalm source:
  It looks like the cause is this stub:
  https://github.com/vimeo/psalm/blob/6.x/stubs/CoreImmutableClasses.phpstub#L94
  where parameter is incorrectly named $unixtimestamp.

Expected Behavior

Psalm should allow using timestamp as a valid named argument for DateTimeImmutable::setTimestamp.

Environment

• Psalm version: 6.x
• PHP version: 8.2
• Platform: tested on online playground and local.