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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Inconsistencies in error propagation after calling `_PyFrame_GetFrameObject`","articleBody":"# Bug report\n\n### Bug description:\n\nThere are 3 callers of `_PyFrame_GetFrameObject` which explicitly clear error when it returns NULL. \n\n1. `take_ownership` https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/frame.c#L74-L79\n2. `PyEval_GetFrame` https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/ceval.c#L2562-L2564\n3. `PyThreadState_GetFrame` https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/pystate.c#L2101-L2103\n\n`PyEval_GetFrame` and `PyThreadState_GetFrame` docs say that NULL is returned when \"no frame is currently executing\", and doesn't say anything about any error (probably as they explicitly clear it?). \n\nI wonder whether `PyFrame_GetBack` also would want to clear error \nhttps://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Objects/frameobject.c#L2407-L2409\n\n`PyFrame_GetBack`'s documentation doesn't say anything about `MemoryError` which can be set by its internal API calls https://docs.python.org/3.15/c-api/frame.html#c.PyFrame_GetBack\n\nThe rest of the `_PyFrame_GetFrameObject` callers that don't clear error including `PyFrame_GetBack` are\n\n- [`_PyEval_ExceptionGroupMatch`](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/ceval.c#L2234)\n- [`_PyEval_EvalFrameDefault` (error label)](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/bytecodes.c#L5731)\n- [`_gen_getframe`](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Objects/genobject.c#L960)\n- [`sys__getframe_impl`](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/sysmodule.c#L2122)\n- [`_PyThread_CurrentFrames`](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/pystate.c#L2699)\n- [`_Py_call_instrumentation_line`](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/instrumentation.c#L1336)\n- [`_PyFrame_GetLocals`](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Objects/frameobject.c#L2299)\n- [`PyEval_GetLocals`](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Python/ceval.c#L2616) — Public C API (deprecated), no NULL check\n- [`PyFrame_GetBack`](https://github.com/python/cpython/blob/b67a64d7e277b6ab7b4d77e12f35c58b64f55e65/Objects/frameobject.c#L2408) — Public C API, no NULL check\n\n\nAnd `PyEval_GetLocals` and `PyFrame_GetBack` are public C APIs that don't check for NULL and don't clear the error. I guess the internals are ok to propagate the errors? \n\nCan someone explain whether `PyFrame_GetBack` not clearing error on null is ok/intended or it's a discrepancy/bug? \n\nI would prefer `PyFrame_GetBack` to not propagate an error given that its documentation doesn't say anything about MemoryError. \n\n### CPython versions tested on:\n\nCPython main branch\n\n### Operating systems tested on:\n\n_No response_\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-144824\n* gh-145318\n* gh-145319\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/taegyunkim","@type":"Person","name":"taegyunkim"},"datePublished":"2026-02-10T22:15:26.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":6},"url":"https://github.com/144693/cpython/issues/144693"}