fix(pyo3-bytes): don't panic on b"" in Bytes or a huge Bytes * n

[kylebarron]

Note

This PR was written by Claude (Claude Code), not by @kylebarron.

Makes in and * on obstore.Bytes behave like bytes instead of raising PanicException or aborting the interpreter.

Closes #786

Changes

• __contains__: an empty needle now returns True. Before, it went to slice::windows(0), which panics even for an empty haystack.
• __mul__: now raises OverflowError("repeated bytes are too long") when len * n overflows or exceeds isize::MAX, and MemoryError when the allocation fails (via Vec::try_reserve_exact). Before, it passed len * n straight to BytesMut::with_capacity, which panics past isize::MAX and aborts the process on allocation failure.
• __mul__ on an empty Bytes: now returns immediately. Found while testing, not in the issue: Bytes(b"") * (1 << 62) looped n times appending an empty slice, so it hung, where bytes returns b"" right away.
• Fixes the Bytes.__mul__ type hint, which claimed (other: Buffer) -> int. It now takes an int and returns Bytes. Pyright rejected the new tests without this.
• Bumps pyo3-bytes to 0.7.2, with a changelog entry.

expression	bytes	Bytes before	Bytes after
b"" in B(b"abc")	True	PanicException	True
B(b"abc") * (1 << 62)	OverflowError	PanicException: capacity overflow	OverflowError
B(b"a") * (1 << 62)	MemoryError	process abort (exit 134)	MemoryError
B(b"") * (1 << 62)	b""	hangs	empty Bytes

Temporary path dependency

obstore depends on pyo3-bytes from crates.io, so the Python tests would otherwise keep exercising the published 0.7.1. The first commit points obstore at ../pyo3-bytes so CI tests this fix. Once this merges and pyo3-bytes-v0.7.2 is tagged and published, obstore can go back to the crates.io release.

Tests

New tests in tests/test_bytes.py: in compared against bytes for empty and non-empty needles and haystacks, ordinary repetition compared against bytes, and one test each for the OverflowError, MemoryError, and empty-Bytes cases. Against the unfixed code, the empty-needle cases fail with PanicException, the overflow test fails with PanicException, the MemoryError test aborts pytest, and the empty-Bytes test hangs.

Locally (macOS arm64): the full suite passes on 3.14 and on 3.14t with --parallel-threads=2 (445 passed, 2 xfailed). cargo fmt, cargo clippy -D warnings (root and pyo3-bytes), cargo test --all, pyright 1.1.406, and pre-commit all pass.

🤖 Written by Claude Code