bugs.json

{
  "_meta": {
    "source": "MicroPython tests/basics differential vs CPython 3.13",
    "verified": "each repro re-run through VM + python3",
    "count": 4,
    "fixed": "100 bugs fixed in vm.json: try/finally unwinding, yield-from expressions, range overflow/truncation/contains, in-place set ops, del of closures, lt sorting, nested next() corruption, nested generator/comprehension ForIter relocation, nested-call spread-arg count corruption, spread-arg after keyword, kwarg name colliding with *args/**kwargs param, kwarg duplicated into **kwargs."
  },
  "bugs": [
    {
      "id": "assign_expr",
      "category": "control-flow",
      "summary": "any() does not short-circuit, so a walrus var assigned inside the generator keeps the last-iteration value instead of stopping at the matching element.",
      "repro": "def foo():\n    any((hit := i) == 8 for i in range(20))\n    return hit\nprint(foo())",
      "expected": "8",
      "actual": "19"
    },
    {
      "id": "gen_yield_from_executing",
      "category": "scoping",
      "summary": "A generator that yields from itself via a module-global name raises NameError on that validly-bound name instead of the expected ValueError; the global binding is lost on generator re-entry.",
      "repro": "def f():\n    yield 1\n    yield from g\ng = f()\nprint(next(g))\ntry:\n    next(g)\nexcept ValueError:\n    print('ValueError')",
      "expected": "1\nValueError",
      "actual": "1"
    },
    {
      "id": "scope_implicit",
      "category": "scoping",
      "summary": "Implicit nonlocal closure over a variable defined in the enclosing scope after the nested function raises NameError instead of capturing it.",
      "repro": "def f():\n    def g():\n        return x\n    x = 3\n    return g\nprint(f()())",
      "expected": "3",
      "actual": "__VMERR__ NameError: name 'x' is not defined"
    },
    {
      "id": "global_rebind_cross_function",
      "category": "scoping",
      "summary": "A global rebind inside one function is invisible to reads from other functions; in-place mutation propagates. Found building dom batch(); also pinned red in vm.json. Note: fix host/dom/src/entry.py line 25 around after this.",
      "repro": "x = [1]\ndef rebind():\n    global x\n    x = []\ndef read():\n    return len(x)\nrebind()\nprint(read())",
      "expected": "0",
      "actual": "1"
    }
  ]
}