René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Inference failure in `return` statement with `next` and `or`","articleBody":"The following MWE ([mypy-playground](https://mypy-play.net/?mypy=master\u0026python=3.11\u0026flags=strict\u0026gist=9dccc7c6071cb4568db291adc3558a48)):\r\n```python\r\nfrom typing import Iterator\r\n\r\ndef this_fails(numbers: Iterator[int]) -\u003e int:\r\n  return next(numbers, None) or 0\r\n  \r\ndef intermediate_is_ok(numbers: Iterator[int]) -\u003e int:\r\n  my_number = next(numbers, None) or 0\r\n  return my_number\r\n\r\ndef separate_line_is_ok(numbers: Iterator[int]) -\u003e int:\r\n  result = next(numbers, None)\r\n  return result or 0\r\n  \r\ndef using_default_directly_is_ok(numbers: Iterator[int]) -\u003e int:\r\n  return next(numbers, 0)\r\n\r\ndef having_optional_int_with_or_is_ok(number_maybe: int | None) -\u003e int:\r\n  return number_maybe or 0\r\n```\r\nproduces the following report on `master`:\r\n```\r\nmain.py:4: error: Argument 2 to \"next\" has incompatible type \"None\"; expected \"int\"  [arg-type]\r\n```\r\nThis is incorrect as `next(numbers, None) or 0` is always `int`.\r\nAll close variants, including assigning it to an intermediate variable, don't have this issue. \r\nI can't think of an actual application where you would want to write code like this, but I figured it's an interesting interaction that might warrant investigation.\r\n\r\nI couldn't find an open issue about this and I asked in Gitter.\r\n\r\n\r\n","author":{"url":"https://github.com/PGijsbers","@type":"Person","name":"PGijsbers"},"datePublished":"2023-07-23T20:42:17.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/15755/mypy/issues/15755"}