Narrow encode_into offset stub type to int - #1163
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The type stubs for `msgspec.json.Encoder.encode_into` and `msgspec.msgpack.Encoder.encode_into` declared `offset: int | None = 0`, but the C implementation passes the argument to `PyLong_AsSsize_t` and raises `TypeError: an integer is required` for `None`. The docstring also documents `offset : int, optional`, with `-1` (not `None`) as the sentinel for writing at the end of the buffer. Narrow the stubs to `int` and add type-level and runtime regression tests.
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Thx for the fix and for adding regression tests for both encoders!
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Widening the runtime to accept
Nonewas the alternative. I rejected it: the docstring specifiesoffset : int, optionaland reserves-1as the sentinel for writing at the end of the buffer, which leavesNonewith no meaning to carry. Narrowing the stub makes the declared type match both the C code and the documented contract.The
int | Nonetraces back to the originalOptional[int]annotation and survived the 3.10+ syntax migration in #1041. Nothing in the tree passesNone.Residual limitation: this edits the same two stub lines as open PR #1160, which reshapes
bufferand the return type while keepingoffset: int | None. Whichever lands second needs a one-line rebase. The two changes are otherwise independent, since #1160 keeps readingoffsetviaPyLong_AsSsize_t.Measurement, CPython 3.14:
just test-typingclean under mypy 2.3.0, pyright 1.1.411, pyrefly 1.2.0.basic_typing_examples.py, so the type-level test is not vacuous.pytest tests/unit: 6119 passed, 404 skipped, identical to the pre-change baseline. The two runtime assertions are pins on current behavior rather than new coverage.ruff formatcollapses the signature onto one line once| Noneis gone; that reformat is included.No changelog entry, following merged stub PRs #1055, #1057, #1062, #1065, #1074 and #1093, which leave it to the aggregated "type stub improvements" line at release.